2cos (problem 3.3.5)

Percentage Accurate: 38.1% → 99.5%
Time: 19.1s
Alternatives: 15
Speedup: 1.9×

Specification

?
\[\begin{array}{l} \\ \cos \left(x + \varepsilon\right) - \cos x \end{array} \]
(FPCore (x eps) :precision binary64 (- (cos (+ x eps)) (cos x)))
double code(double x, double eps) {
	return cos((x + eps)) - cos(x);
}
real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    code = cos((x + eps)) - cos(x)
end function
public static double code(double x, double eps) {
	return Math.cos((x + eps)) - Math.cos(x);
}
def code(x, eps):
	return math.cos((x + eps)) - math.cos(x)
function code(x, eps)
	return Float64(cos(Float64(x + eps)) - cos(x))
end
function tmp = code(x, eps)
	tmp = cos((x + eps)) - cos(x);
end
code[x_, eps_] := N[(N[Cos[N[(x + eps), $MachinePrecision]], $MachinePrecision] - N[Cos[x], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\cos \left(x + \varepsilon\right) - \cos x
\end{array}

Sampling outcomes in binary64 precision:

Local Percentage Accuracy vs ?

The average percentage accuracy by input value. Horizontal axis shows value of an input variable; the variable is choosen in the title. Vertical axis is accuracy; higher is better. Red represent the original program, while blue represents Herbie's suggestion. These can be toggled with buttons below the plot. The line is an average while dots represent individual samples.

Accuracy vs Speed?

Herbie found 15 alternatives:

AlternativeAccuracySpeedup
The accuracy (vertical axis) and speed (horizontal axis) of each alternatives. Up and to the right is better. The red square shows the initial program, and each blue circle shows an alternative.The line shows the best available speed-accuracy tradeoffs.

Initial Program: 38.1% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \cos \left(x + \varepsilon\right) - \cos x \end{array} \]
(FPCore (x eps) :precision binary64 (- (cos (+ x eps)) (cos x)))
double code(double x, double eps) {
	return cos((x + eps)) - cos(x);
}
real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    code = cos((x + eps)) - cos(x)
end function
public static double code(double x, double eps) {
	return Math.cos((x + eps)) - Math.cos(x);
}
def code(x, eps):
	return math.cos((x + eps)) - math.cos(x)
function code(x, eps)
	return Float64(cos(Float64(x + eps)) - cos(x))
end
function tmp = code(x, eps)
	tmp = cos((x + eps)) - cos(x);
end
code[x_, eps_] := N[(N[Cos[N[(x + eps), $MachinePrecision]], $MachinePrecision] - N[Cos[x], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\cos \left(x + \varepsilon\right) - \cos x
\end{array}

Alternative 1: 99.5% accurate, 0.3× speedup?

\[\begin{array}{l} \\ \mathsf{fma}\left(\cos x, \tan \left(\frac{\varepsilon}{2}\right) \cdot \left(-\sin \varepsilon\right), \sin \varepsilon \cdot \left(-\sin x\right)\right) \end{array} \]
(FPCore (x eps)
 :precision binary64
 (fma (cos x) (* (tan (/ eps 2.0)) (- (sin eps))) (* (sin eps) (- (sin x)))))
double code(double x, double eps) {
	return fma(cos(x), (tan((eps / 2.0)) * -sin(eps)), (sin(eps) * -sin(x)));
}
function code(x, eps)
	return fma(cos(x), Float64(tan(Float64(eps / 2.0)) * Float64(-sin(eps))), Float64(sin(eps) * Float64(-sin(x))))
end
code[x_, eps_] := N[(N[Cos[x], $MachinePrecision] * N[(N[Tan[N[(eps / 2.0), $MachinePrecision]], $MachinePrecision] * (-N[Sin[eps], $MachinePrecision])), $MachinePrecision] + N[(N[Sin[eps], $MachinePrecision] * (-N[Sin[x], $MachinePrecision])), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\mathsf{fma}\left(\cos x, \tan \left(\frac{\varepsilon}{2}\right) \cdot \left(-\sin \varepsilon\right), \sin \varepsilon \cdot \left(-\sin x\right)\right)
\end{array}
Derivation
  1. Initial program 37.2%

    \[\cos \left(x + \varepsilon\right) - \cos x \]
  2. Step-by-step derivation
    1. cos-sum64.3%

      \[\leadsto \color{blue}{\left(\cos x \cdot \cos \varepsilon - \sin x \cdot \sin \varepsilon\right)} - \cos x \]
    2. associate--l-64.4%

      \[\leadsto \color{blue}{\cos x \cdot \cos \varepsilon - \left(\sin x \cdot \sin \varepsilon + \cos x\right)} \]
    3. fma-neg64.4%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon, -\left(\sin x \cdot \sin \varepsilon + \cos x\right)\right)} \]
    4. fma-def64.4%

      \[\leadsto \mathsf{fma}\left(\cos x, \cos \varepsilon, -\color{blue}{\mathsf{fma}\left(\sin x, \sin \varepsilon, \cos x\right)}\right) \]
  3. Applied egg-rr64.4%

    \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon, -\mathsf{fma}\left(\sin x, \sin \varepsilon, \cos x\right)\right)} \]
  4. Taylor expanded in x around inf 64.4%

    \[\leadsto \color{blue}{\cos \varepsilon \cdot \cos x - \left(\cos x + \sin \varepsilon \cdot \sin x\right)} \]
  5. Step-by-step derivation
    1. associate--r+89.8%

      \[\leadsto \color{blue}{\left(\cos \varepsilon \cdot \cos x - \cos x\right) - \sin \varepsilon \cdot \sin x} \]
    2. *-commutative89.8%

      \[\leadsto \left(\color{blue}{\cos x \cdot \cos \varepsilon} - \cos x\right) - \sin \varepsilon \cdot \sin x \]
    3. *-rgt-identity89.8%

      \[\leadsto \left(\cos x \cdot \cos \varepsilon - \color{blue}{\cos x \cdot 1}\right) - \sin \varepsilon \cdot \sin x \]
    4. distribute-lft-out--89.8%

      \[\leadsto \color{blue}{\cos x \cdot \left(\cos \varepsilon - 1\right)} - \sin \varepsilon \cdot \sin x \]
    5. sub-neg89.8%

      \[\leadsto \cos x \cdot \color{blue}{\left(\cos \varepsilon + \left(-1\right)\right)} - \sin \varepsilon \cdot \sin x \]
    6. metadata-eval89.8%

      \[\leadsto \cos x \cdot \left(\cos \varepsilon + \color{blue}{-1}\right) - \sin \varepsilon \cdot \sin x \]
    7. *-commutative89.8%

      \[\leadsto \cos x \cdot \left(\cos \varepsilon + -1\right) - \color{blue}{\sin x \cdot \sin \varepsilon} \]
    8. fma-neg89.8%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon + -1, -\sin x \cdot \sin \varepsilon\right)} \]
    9. +-commutative89.8%

      \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{-1 + \cos \varepsilon}, -\sin x \cdot \sin \varepsilon\right) \]
    10. distribute-rgt-neg-in89.8%

      \[\leadsto \mathsf{fma}\left(\cos x, -1 + \cos \varepsilon, \color{blue}{\sin x \cdot \left(-\sin \varepsilon\right)}\right) \]
  6. Simplified89.8%

    \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, -1 + \cos \varepsilon, \sin x \cdot \left(-\sin \varepsilon\right)\right)} \]
  7. Step-by-step derivation
    1. flip-+89.5%

      \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{\frac{-1 \cdot -1 - \cos \varepsilon \cdot \cos \varepsilon}{-1 - \cos \varepsilon}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    2. frac-2neg89.5%

      \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{\frac{-\left(-1 \cdot -1 - \cos \varepsilon \cdot \cos \varepsilon\right)}{-\left(-1 - \cos \varepsilon\right)}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    3. metadata-eval89.5%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{-\left(\color{blue}{1} - \cos \varepsilon \cdot \cos \varepsilon\right)}{-\left(-1 - \cos \varepsilon\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    4. 1-sub-cos99.2%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{-\color{blue}{\sin \varepsilon \cdot \sin \varepsilon}}{-\left(-1 - \cos \varepsilon\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    5. add-sqr-sqrt46.1%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{-\color{blue}{\left(\sqrt{\sin \varepsilon} \cdot \sqrt{\sin \varepsilon}\right)} \cdot \sin \varepsilon}{-\left(-1 - \cos \varepsilon\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    6. sqrt-unprod67.7%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{-\color{blue}{\sqrt{\sin \varepsilon \cdot \sin \varepsilon}} \cdot \sin \varepsilon}{-\left(-1 - \cos \varepsilon\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    7. sqr-neg67.7%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{-\sqrt{\color{blue}{\left(-\sin \varepsilon\right) \cdot \left(-\sin \varepsilon\right)}} \cdot \sin \varepsilon}{-\left(-1 - \cos \varepsilon\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    8. sqrt-unprod21.5%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{-\color{blue}{\left(\sqrt{-\sin \varepsilon} \cdot \sqrt{-\sin \varepsilon}\right)} \cdot \sin \varepsilon}{-\left(-1 - \cos \varepsilon\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    9. add-sqr-sqrt40.5%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{-\color{blue}{\left(-\sin \varepsilon\right)} \cdot \sin \varepsilon}{-\left(-1 - \cos \varepsilon\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    10. distribute-rgt-neg-out40.5%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{\color{blue}{\left(-\sin \varepsilon\right) \cdot \left(-\sin \varepsilon\right)}}{-\left(-1 - \cos \varepsilon\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    11. sqr-neg40.5%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{\color{blue}{\sin \varepsilon \cdot \sin \varepsilon}}{-\left(-1 - \cos \varepsilon\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    12. pow240.5%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{\color{blue}{{\sin \varepsilon}^{2}}}{-\left(-1 - \cos \varepsilon\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    13. flip--3.9%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{{\sin \varepsilon}^{2}}{-\color{blue}{\frac{-1 \cdot -1 - \cos \varepsilon \cdot \cos \varepsilon}{-1 + \cos \varepsilon}}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
  8. Applied egg-rr99.2%

    \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{\frac{{\sin \varepsilon}^{2}}{-\left(\cos \varepsilon + 1\right)}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
  9. Step-by-step derivation
    1. neg-sub099.2%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{{\sin \varepsilon}^{2}}{\color{blue}{0 - \left(\cos \varepsilon + 1\right)}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    2. +-commutative99.2%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{{\sin \varepsilon}^{2}}{0 - \color{blue}{\left(1 + \cos \varepsilon\right)}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    3. associate--r+99.2%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{{\sin \varepsilon}^{2}}{\color{blue}{\left(0 - 1\right) - \cos \varepsilon}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    4. metadata-eval99.2%

      \[\leadsto \mathsf{fma}\left(\cos x, \frac{{\sin \varepsilon}^{2}}{\color{blue}{-1} - \cos \varepsilon}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
  10. Simplified99.2%

    \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{\frac{{\sin \varepsilon}^{2}}{-1 - \cos \varepsilon}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
  11. Taylor expanded in eps around inf 99.2%

    \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{-1 \cdot \frac{{\sin \varepsilon}^{2}}{1 + \cos \varepsilon}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
  12. Step-by-step derivation
    1. mul-1-neg99.2%

      \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{-\frac{{\sin \varepsilon}^{2}}{1 + \cos \varepsilon}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    2. +-commutative99.2%

      \[\leadsto \mathsf{fma}\left(\cos x, -\frac{{\sin \varepsilon}^{2}}{\color{blue}{\cos \varepsilon + 1}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    3. unpow299.2%

      \[\leadsto \mathsf{fma}\left(\cos x, -\frac{\color{blue}{\sin \varepsilon \cdot \sin \varepsilon}}{\cos \varepsilon + 1}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    4. associate-*r/99.1%

      \[\leadsto \mathsf{fma}\left(\cos x, -\color{blue}{\sin \varepsilon \cdot \frac{\sin \varepsilon}{\cos \varepsilon + 1}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    5. distribute-rgt-neg-in99.1%

      \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{\sin \varepsilon \cdot \left(-\frac{\sin \varepsilon}{\cos \varepsilon + 1}\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    6. +-commutative99.1%

      \[\leadsto \mathsf{fma}\left(\cos x, \sin \varepsilon \cdot \left(-\frac{\sin \varepsilon}{\color{blue}{1 + \cos \varepsilon}}\right), \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    7. hang-0p-tan99.6%

      \[\leadsto \mathsf{fma}\left(\cos x, \sin \varepsilon \cdot \left(-\color{blue}{\tan \left(\frac{\varepsilon}{2}\right)}\right), \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
  13. Simplified99.6%

    \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{\sin \varepsilon \cdot \left(-\tan \left(\frac{\varepsilon}{2}\right)\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
  14. Final simplification99.6%

    \[\leadsto \mathsf{fma}\left(\cos x, \tan \left(\frac{\varepsilon}{2}\right) \cdot \left(-\sin \varepsilon\right), \sin \varepsilon \cdot \left(-\sin x\right)\right) \]

Alternative 2: 99.1% accurate, 0.4× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \sin \left(\varepsilon \cdot 0.5\right)\\ \mathbf{if}\;x \leq -2.95 \cdot 10^{-8} \lor \neg \left(x \leq 2.15 \cdot 10^{-40}\right):\\ \;\;\;\;\mathsf{fma}\left(\cos x, \cos \varepsilon + -1, \sin \varepsilon \cdot \left(-\sin x\right)\right)\\ \mathbf{else}:\\ \;\;\;\;\left(t_0 + x \cdot \cos \left(\varepsilon \cdot 0.5\right)\right) \cdot \left(t_0 \cdot -2\right)\\ \end{array} \end{array} \]
(FPCore (x eps)
 :precision binary64
 (let* ((t_0 (sin (* eps 0.5))))
   (if (or (<= x -2.95e-8) (not (<= x 2.15e-40)))
     (fma (cos x) (+ (cos eps) -1.0) (* (sin eps) (- (sin x))))
     (* (+ t_0 (* x (cos (* eps 0.5)))) (* t_0 -2.0)))))
double code(double x, double eps) {
	double t_0 = sin((eps * 0.5));
	double tmp;
	if ((x <= -2.95e-8) || !(x <= 2.15e-40)) {
		tmp = fma(cos(x), (cos(eps) + -1.0), (sin(eps) * -sin(x)));
	} else {
		tmp = (t_0 + (x * cos((eps * 0.5)))) * (t_0 * -2.0);
	}
	return tmp;
}
function code(x, eps)
	t_0 = sin(Float64(eps * 0.5))
	tmp = 0.0
	if ((x <= -2.95e-8) || !(x <= 2.15e-40))
		tmp = fma(cos(x), Float64(cos(eps) + -1.0), Float64(sin(eps) * Float64(-sin(x))));
	else
		tmp = Float64(Float64(t_0 + Float64(x * cos(Float64(eps * 0.5)))) * Float64(t_0 * -2.0));
	end
	return tmp
end
code[x_, eps_] := Block[{t$95$0 = N[Sin[N[(eps * 0.5), $MachinePrecision]], $MachinePrecision]}, If[Or[LessEqual[x, -2.95e-8], N[Not[LessEqual[x, 2.15e-40]], $MachinePrecision]], N[(N[Cos[x], $MachinePrecision] * N[(N[Cos[eps], $MachinePrecision] + -1.0), $MachinePrecision] + N[(N[Sin[eps], $MachinePrecision] * (-N[Sin[x], $MachinePrecision])), $MachinePrecision]), $MachinePrecision], N[(N[(t$95$0 + N[(x * N[Cos[N[(eps * 0.5), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] * N[(t$95$0 * -2.0), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \sin \left(\varepsilon \cdot 0.5\right)\\
\mathbf{if}\;x \leq -2.95 \cdot 10^{-8} \lor \neg \left(x \leq 2.15 \cdot 10^{-40}\right):\\
\;\;\;\;\mathsf{fma}\left(\cos x, \cos \varepsilon + -1, \sin \varepsilon \cdot \left(-\sin x\right)\right)\\

\mathbf{else}:\\
\;\;\;\;\left(t_0 + x \cdot \cos \left(\varepsilon \cdot 0.5\right)\right) \cdot \left(t_0 \cdot -2\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < -2.9499999999999999e-8 or 2.1500000000000001e-40 < x

    1. Initial program 9.8%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Step-by-step derivation
      1. cos-sum59.2%

        \[\leadsto \color{blue}{\left(\cos x \cdot \cos \varepsilon - \sin x \cdot \sin \varepsilon\right)} - \cos x \]
      2. associate--l-59.3%

        \[\leadsto \color{blue}{\cos x \cdot \cos \varepsilon - \left(\sin x \cdot \sin \varepsilon + \cos x\right)} \]
      3. fma-neg59.3%

        \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon, -\left(\sin x \cdot \sin \varepsilon + \cos x\right)\right)} \]
      4. fma-def59.3%

        \[\leadsto \mathsf{fma}\left(\cos x, \cos \varepsilon, -\color{blue}{\mathsf{fma}\left(\sin x, \sin \varepsilon, \cos x\right)}\right) \]
    3. Applied egg-rr59.3%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon, -\mathsf{fma}\left(\sin x, \sin \varepsilon, \cos x\right)\right)} \]
    4. Taylor expanded in x around inf 59.3%

      \[\leadsto \color{blue}{\cos \varepsilon \cdot \cos x - \left(\cos x + \sin \varepsilon \cdot \sin x\right)} \]
    5. Step-by-step derivation
      1. associate--r+99.2%

        \[\leadsto \color{blue}{\left(\cos \varepsilon \cdot \cos x - \cos x\right) - \sin \varepsilon \cdot \sin x} \]
      2. *-commutative99.2%

        \[\leadsto \left(\color{blue}{\cos x \cdot \cos \varepsilon} - \cos x\right) - \sin \varepsilon \cdot \sin x \]
      3. *-rgt-identity99.2%

        \[\leadsto \left(\cos x \cdot \cos \varepsilon - \color{blue}{\cos x \cdot 1}\right) - \sin \varepsilon \cdot \sin x \]
      4. distribute-lft-out--99.1%

        \[\leadsto \color{blue}{\cos x \cdot \left(\cos \varepsilon - 1\right)} - \sin \varepsilon \cdot \sin x \]
      5. sub-neg99.1%

        \[\leadsto \cos x \cdot \color{blue}{\left(\cos \varepsilon + \left(-1\right)\right)} - \sin \varepsilon \cdot \sin x \]
      6. metadata-eval99.1%

        \[\leadsto \cos x \cdot \left(\cos \varepsilon + \color{blue}{-1}\right) - \sin \varepsilon \cdot \sin x \]
      7. *-commutative99.1%

        \[\leadsto \cos x \cdot \left(\cos \varepsilon + -1\right) - \color{blue}{\sin x \cdot \sin \varepsilon} \]
      8. fma-neg99.1%

        \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon + -1, -\sin x \cdot \sin \varepsilon\right)} \]
      9. +-commutative99.1%

        \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{-1 + \cos \varepsilon}, -\sin x \cdot \sin \varepsilon\right) \]
      10. distribute-rgt-neg-in99.1%

        \[\leadsto \mathsf{fma}\left(\cos x, -1 + \cos \varepsilon, \color{blue}{\sin x \cdot \left(-\sin \varepsilon\right)}\right) \]
    6. Simplified99.1%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, -1 + \cos \varepsilon, \sin x \cdot \left(-\sin \varepsilon\right)\right)} \]

    if -2.9499999999999999e-8 < x < 2.1500000000000001e-40

    1. Initial program 69.8%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Step-by-step derivation
      1. diff-cos90.9%

        \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\frac{\left(x + \varepsilon\right) - x}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right)} \]
      2. div-inv90.9%

        \[\leadsto -2 \cdot \left(\sin \color{blue}{\left(\left(\left(x + \varepsilon\right) - x\right) \cdot \frac{1}{2}\right)} \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      3. associate--l+90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\color{blue}{\left(x + \left(\varepsilon - x\right)\right)} \cdot \frac{1}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      4. metadata-eval90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot \color{blue}{0.5}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      5. div-inv90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \color{blue}{\left(\left(\left(x + \varepsilon\right) + x\right) \cdot \frac{1}{2}\right)}\right) \]
      6. +-commutative90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\color{blue}{\left(\varepsilon + x\right)} + x\right) \cdot \frac{1}{2}\right)\right) \]
      7. associate-+l+90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\color{blue}{\left(\varepsilon + \left(x + x\right)\right)} \cdot \frac{1}{2}\right)\right) \]
      8. metadata-eval90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot \color{blue}{0.5}\right)\right) \]
    3. Applied egg-rr90.9%

      \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)\right)} \]
    4. Step-by-step derivation
      1. associate-*r*90.9%

        \[\leadsto \color{blue}{\left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)} \]
      2. *-commutative90.9%

        \[\leadsto \color{blue}{\sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right)} \]
      3. *-commutative90.9%

        \[\leadsto \sin \color{blue}{\left(0.5 \cdot \left(\varepsilon + \left(x + x\right)\right)\right)} \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      4. +-commutative90.9%

        \[\leadsto \sin \left(0.5 \cdot \color{blue}{\left(\left(x + x\right) + \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      5. count-290.9%

        \[\leadsto \sin \left(0.5 \cdot \left(\color{blue}{2 \cdot x} + \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      6. fma-def90.9%

        \[\leadsto \sin \left(0.5 \cdot \color{blue}{\mathsf{fma}\left(2, x, \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      7. sub-neg90.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(\varepsilon + \left(-x\right)\right)}\right) \cdot 0.5\right)\right) \]
      8. mul-1-neg90.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon + \color{blue}{-1 \cdot x}\right)\right) \cdot 0.5\right)\right) \]
      9. +-commutative90.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(-1 \cdot x + \varepsilon\right)}\right) \cdot 0.5\right)\right) \]
      10. associate-+r+98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(\left(x + -1 \cdot x\right) + \varepsilon\right)} \cdot 0.5\right)\right) \]
      11. mul-1-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\left(x + \color{blue}{\left(-x\right)}\right) + \varepsilon\right) \cdot 0.5\right)\right) \]
      12. sub-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{\left(x - x\right)} + \varepsilon\right) \cdot 0.5\right)\right) \]
      13. +-inverses98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{0} + \varepsilon\right) \cdot 0.5\right)\right) \]
      14. remove-double-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \color{blue}{\left(-\left(-\varepsilon\right)\right)}\right) \cdot 0.5\right)\right) \]
      15. mul-1-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \left(-\color{blue}{-1 \cdot \varepsilon}\right)\right) \cdot 0.5\right)\right) \]
      16. sub-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(0 - -1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
      17. neg-sub098.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(--1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
      18. mul-1-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(-\color{blue}{\left(-\varepsilon\right)}\right) \cdot 0.5\right)\right) \]
      19. remove-double-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\varepsilon} \cdot 0.5\right)\right) \]
    5. Simplified98.9%

      \[\leadsto \color{blue}{\sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\varepsilon \cdot 0.5\right)\right)} \]
    6. Taylor expanded in x around 0 99.6%

      \[\leadsto \color{blue}{\left(\sin \left(0.5 \cdot \varepsilon\right) + x \cdot \cos \left(0.5 \cdot \varepsilon\right)\right)} \cdot \left(-2 \cdot \sin \left(\varepsilon \cdot 0.5\right)\right) \]
  3. Recombined 2 regimes into one program.
  4. Final simplification99.3%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -2.95 \cdot 10^{-8} \lor \neg \left(x \leq 2.15 \cdot 10^{-40}\right):\\ \;\;\;\;\mathsf{fma}\left(\cos x, \cos \varepsilon + -1, \sin \varepsilon \cdot \left(-\sin x\right)\right)\\ \mathbf{else}:\\ \;\;\;\;\left(\sin \left(\varepsilon \cdot 0.5\right) + x \cdot \cos \left(\varepsilon \cdot 0.5\right)\right) \cdot \left(\sin \left(\varepsilon \cdot 0.5\right) \cdot -2\right)\\ \end{array} \]

Alternative 3: 99.1% accurate, 0.4× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \sin \left(\varepsilon \cdot 0.5\right)\\ \mathbf{if}\;x \leq -2.75 \cdot 10^{-8}:\\ \;\;\;\;\left(\cos x \cdot \cos \varepsilon - \cos x\right) - \sin \varepsilon \cdot \sin x\\ \mathbf{elif}\;x \leq 4.4 \cdot 10^{-41}:\\ \;\;\;\;\left(t_0 + x \cdot \cos \left(\varepsilon \cdot 0.5\right)\right) \cdot \left(t_0 \cdot -2\right)\\ \mathbf{else}:\\ \;\;\;\;\mathsf{fma}\left(\cos x, \cos \varepsilon + -1, \sin \varepsilon \cdot \left(-\sin x\right)\right)\\ \end{array} \end{array} \]
(FPCore (x eps)
 :precision binary64
 (let* ((t_0 (sin (* eps 0.5))))
   (if (<= x -2.75e-8)
     (- (- (* (cos x) (cos eps)) (cos x)) (* (sin eps) (sin x)))
     (if (<= x 4.4e-41)
       (* (+ t_0 (* x (cos (* eps 0.5)))) (* t_0 -2.0))
       (fma (cos x) (+ (cos eps) -1.0) (* (sin eps) (- (sin x))))))))
double code(double x, double eps) {
	double t_0 = sin((eps * 0.5));
	double tmp;
	if (x <= -2.75e-8) {
		tmp = ((cos(x) * cos(eps)) - cos(x)) - (sin(eps) * sin(x));
	} else if (x <= 4.4e-41) {
		tmp = (t_0 + (x * cos((eps * 0.5)))) * (t_0 * -2.0);
	} else {
		tmp = fma(cos(x), (cos(eps) + -1.0), (sin(eps) * -sin(x)));
	}
	return tmp;
}
function code(x, eps)
	t_0 = sin(Float64(eps * 0.5))
	tmp = 0.0
	if (x <= -2.75e-8)
		tmp = Float64(Float64(Float64(cos(x) * cos(eps)) - cos(x)) - Float64(sin(eps) * sin(x)));
	elseif (x <= 4.4e-41)
		tmp = Float64(Float64(t_0 + Float64(x * cos(Float64(eps * 0.5)))) * Float64(t_0 * -2.0));
	else
		tmp = fma(cos(x), Float64(cos(eps) + -1.0), Float64(sin(eps) * Float64(-sin(x))));
	end
	return tmp
end
code[x_, eps_] := Block[{t$95$0 = N[Sin[N[(eps * 0.5), $MachinePrecision]], $MachinePrecision]}, If[LessEqual[x, -2.75e-8], N[(N[(N[(N[Cos[x], $MachinePrecision] * N[Cos[eps], $MachinePrecision]), $MachinePrecision] - N[Cos[x], $MachinePrecision]), $MachinePrecision] - N[(N[Sin[eps], $MachinePrecision] * N[Sin[x], $MachinePrecision]), $MachinePrecision]), $MachinePrecision], If[LessEqual[x, 4.4e-41], N[(N[(t$95$0 + N[(x * N[Cos[N[(eps * 0.5), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] * N[(t$95$0 * -2.0), $MachinePrecision]), $MachinePrecision], N[(N[Cos[x], $MachinePrecision] * N[(N[Cos[eps], $MachinePrecision] + -1.0), $MachinePrecision] + N[(N[Sin[eps], $MachinePrecision] * (-N[Sin[x], $MachinePrecision])), $MachinePrecision]), $MachinePrecision]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \sin \left(\varepsilon \cdot 0.5\right)\\
\mathbf{if}\;x \leq -2.75 \cdot 10^{-8}:\\
\;\;\;\;\left(\cos x \cdot \cos \varepsilon - \cos x\right) - \sin \varepsilon \cdot \sin x\\

\mathbf{elif}\;x \leq 4.4 \cdot 10^{-41}:\\
\;\;\;\;\left(t_0 + x \cdot \cos \left(\varepsilon \cdot 0.5\right)\right) \cdot \left(t_0 \cdot -2\right)\\

\mathbf{else}:\\
\;\;\;\;\mathsf{fma}\left(\cos x, \cos \varepsilon + -1, \sin \varepsilon \cdot \left(-\sin x\right)\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if x < -2.7500000000000001e-8

    1. Initial program 6.7%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Step-by-step derivation
      1. cos-sum56.6%

        \[\leadsto \color{blue}{\left(\cos x \cdot \cos \varepsilon - \sin x \cdot \sin \varepsilon\right)} - \cos x \]
      2. associate--l-56.6%

        \[\leadsto \color{blue}{\cos x \cdot \cos \varepsilon - \left(\sin x \cdot \sin \varepsilon + \cos x\right)} \]
      3. fma-neg56.7%

        \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon, -\left(\sin x \cdot \sin \varepsilon + \cos x\right)\right)} \]
      4. fma-def56.6%

        \[\leadsto \mathsf{fma}\left(\cos x, \cos \varepsilon, -\color{blue}{\mathsf{fma}\left(\sin x, \sin \varepsilon, \cos x\right)}\right) \]
    3. Applied egg-rr56.6%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon, -\mathsf{fma}\left(\sin x, \sin \varepsilon, \cos x\right)\right)} \]
    4. Taylor expanded in x around inf 56.6%

      \[\leadsto \color{blue}{\cos \varepsilon \cdot \cos x - \left(\cos x + \sin \varepsilon \cdot \sin x\right)} \]
    5. Step-by-step derivation
      1. associate--r+99.2%

        \[\leadsto \color{blue}{\left(\cos \varepsilon \cdot \cos x - \cos x\right) - \sin \varepsilon \cdot \sin x} \]
      2. *-commutative99.2%

        \[\leadsto \left(\color{blue}{\cos x \cdot \cos \varepsilon} - \cos x\right) - \sin \varepsilon \cdot \sin x \]
      3. *-rgt-identity99.2%

        \[\leadsto \left(\cos x \cdot \cos \varepsilon - \color{blue}{\cos x \cdot 1}\right) - \sin \varepsilon \cdot \sin x \]
      4. distribute-lft-out--99.1%

        \[\leadsto \color{blue}{\cos x \cdot \left(\cos \varepsilon - 1\right)} - \sin \varepsilon \cdot \sin x \]
      5. sub-neg99.1%

        \[\leadsto \cos x \cdot \color{blue}{\left(\cos \varepsilon + \left(-1\right)\right)} - \sin \varepsilon \cdot \sin x \]
      6. metadata-eval99.1%

        \[\leadsto \cos x \cdot \left(\cos \varepsilon + \color{blue}{-1}\right) - \sin \varepsilon \cdot \sin x \]
      7. *-commutative99.1%

        \[\leadsto \cos x \cdot \left(\cos \varepsilon + -1\right) - \color{blue}{\sin x \cdot \sin \varepsilon} \]
      8. fma-neg99.1%

        \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon + -1, -\sin x \cdot \sin \varepsilon\right)} \]
      9. +-commutative99.1%

        \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{-1 + \cos \varepsilon}, -\sin x \cdot \sin \varepsilon\right) \]
      10. distribute-rgt-neg-in99.1%

        \[\leadsto \mathsf{fma}\left(\cos x, -1 + \cos \varepsilon, \color{blue}{\sin x \cdot \left(-\sin \varepsilon\right)}\right) \]
    6. Simplified99.1%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, -1 + \cos \varepsilon, \sin x \cdot \left(-\sin \varepsilon\right)\right)} \]
    7. Taylor expanded in x around inf 99.1%

      \[\leadsto \color{blue}{-1 \cdot \left(\sin \varepsilon \cdot \sin x\right) + \cos x \cdot \left(\cos \varepsilon - 1\right)} \]
    8. Step-by-step derivation
      1. +-commutative99.1%

        \[\leadsto \color{blue}{\cos x \cdot \left(\cos \varepsilon - 1\right) + -1 \cdot \left(\sin \varepsilon \cdot \sin x\right)} \]
      2. sub-neg99.1%

        \[\leadsto \cos x \cdot \color{blue}{\left(\cos \varepsilon + \left(-1\right)\right)} + -1 \cdot \left(\sin \varepsilon \cdot \sin x\right) \]
      3. metadata-eval99.1%

        \[\leadsto \cos x \cdot \left(\cos \varepsilon + \color{blue}{-1}\right) + -1 \cdot \left(\sin \varepsilon \cdot \sin x\right) \]
      4. +-commutative99.1%

        \[\leadsto \cos x \cdot \color{blue}{\left(-1 + \cos \varepsilon\right)} + -1 \cdot \left(\sin \varepsilon \cdot \sin x\right) \]
      5. mul-1-neg99.1%

        \[\leadsto \cos x \cdot \left(-1 + \cos \varepsilon\right) + \color{blue}{\left(-\sin \varepsilon \cdot \sin x\right)} \]
      6. distribute-lft-neg-in99.1%

        \[\leadsto \cos x \cdot \left(-1 + \cos \varepsilon\right) + \color{blue}{\left(-\sin \varepsilon\right) \cdot \sin x} \]
      7. cancel-sign-sub-inv99.1%

        \[\leadsto \color{blue}{\cos x \cdot \left(-1 + \cos \varepsilon\right) - \sin \varepsilon \cdot \sin x} \]
      8. +-commutative99.1%

        \[\leadsto \cos x \cdot \color{blue}{\left(\cos \varepsilon + -1\right)} - \sin \varepsilon \cdot \sin x \]
    9. Simplified99.1%

      \[\leadsto \color{blue}{\cos x \cdot \left(\cos \varepsilon + -1\right) - \sin \varepsilon \cdot \sin x} \]
    10. Step-by-step derivation
      1. distribute-rgt-in99.2%

        \[\leadsto \color{blue}{\left(\cos \varepsilon \cdot \cos x + -1 \cdot \cos x\right)} - \sin \varepsilon \cdot \sin x \]
      2. mul-1-neg99.2%

        \[\leadsto \left(\cos \varepsilon \cdot \cos x + \color{blue}{\left(-\cos x\right)}\right) - \sin \varepsilon \cdot \sin x \]
    11. Applied egg-rr99.2%

      \[\leadsto \color{blue}{\left(\cos \varepsilon \cdot \cos x + \left(-\cos x\right)\right)} - \sin \varepsilon \cdot \sin x \]

    if -2.7500000000000001e-8 < x < 4.4e-41

    1. Initial program 69.8%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Step-by-step derivation
      1. diff-cos90.9%

        \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\frac{\left(x + \varepsilon\right) - x}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right)} \]
      2. div-inv90.9%

        \[\leadsto -2 \cdot \left(\sin \color{blue}{\left(\left(\left(x + \varepsilon\right) - x\right) \cdot \frac{1}{2}\right)} \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      3. associate--l+90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\color{blue}{\left(x + \left(\varepsilon - x\right)\right)} \cdot \frac{1}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      4. metadata-eval90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot \color{blue}{0.5}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      5. div-inv90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \color{blue}{\left(\left(\left(x + \varepsilon\right) + x\right) \cdot \frac{1}{2}\right)}\right) \]
      6. +-commutative90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\color{blue}{\left(\varepsilon + x\right)} + x\right) \cdot \frac{1}{2}\right)\right) \]
      7. associate-+l+90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\color{blue}{\left(\varepsilon + \left(x + x\right)\right)} \cdot \frac{1}{2}\right)\right) \]
      8. metadata-eval90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot \color{blue}{0.5}\right)\right) \]
    3. Applied egg-rr90.9%

      \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)\right)} \]
    4. Step-by-step derivation
      1. associate-*r*90.9%

        \[\leadsto \color{blue}{\left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)} \]
      2. *-commutative90.9%

        \[\leadsto \color{blue}{\sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right)} \]
      3. *-commutative90.9%

        \[\leadsto \sin \color{blue}{\left(0.5 \cdot \left(\varepsilon + \left(x + x\right)\right)\right)} \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      4. +-commutative90.9%

        \[\leadsto \sin \left(0.5 \cdot \color{blue}{\left(\left(x + x\right) + \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      5. count-290.9%

        \[\leadsto \sin \left(0.5 \cdot \left(\color{blue}{2 \cdot x} + \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      6. fma-def90.9%

        \[\leadsto \sin \left(0.5 \cdot \color{blue}{\mathsf{fma}\left(2, x, \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      7. sub-neg90.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(\varepsilon + \left(-x\right)\right)}\right) \cdot 0.5\right)\right) \]
      8. mul-1-neg90.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon + \color{blue}{-1 \cdot x}\right)\right) \cdot 0.5\right)\right) \]
      9. +-commutative90.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(-1 \cdot x + \varepsilon\right)}\right) \cdot 0.5\right)\right) \]
      10. associate-+r+98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(\left(x + -1 \cdot x\right) + \varepsilon\right)} \cdot 0.5\right)\right) \]
      11. mul-1-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\left(x + \color{blue}{\left(-x\right)}\right) + \varepsilon\right) \cdot 0.5\right)\right) \]
      12. sub-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{\left(x - x\right)} + \varepsilon\right) \cdot 0.5\right)\right) \]
      13. +-inverses98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{0} + \varepsilon\right) \cdot 0.5\right)\right) \]
      14. remove-double-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \color{blue}{\left(-\left(-\varepsilon\right)\right)}\right) \cdot 0.5\right)\right) \]
      15. mul-1-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \left(-\color{blue}{-1 \cdot \varepsilon}\right)\right) \cdot 0.5\right)\right) \]
      16. sub-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(0 - -1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
      17. neg-sub098.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(--1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
      18. mul-1-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(-\color{blue}{\left(-\varepsilon\right)}\right) \cdot 0.5\right)\right) \]
      19. remove-double-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\varepsilon} \cdot 0.5\right)\right) \]
    5. Simplified98.9%

      \[\leadsto \color{blue}{\sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\varepsilon \cdot 0.5\right)\right)} \]
    6. Taylor expanded in x around 0 99.6%

      \[\leadsto \color{blue}{\left(\sin \left(0.5 \cdot \varepsilon\right) + x \cdot \cos \left(0.5 \cdot \varepsilon\right)\right)} \cdot \left(-2 \cdot \sin \left(\varepsilon \cdot 0.5\right)\right) \]

    if 4.4e-41 < x

    1. Initial program 12.8%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Step-by-step derivation
      1. cos-sum61.6%

        \[\leadsto \color{blue}{\left(\cos x \cdot \cos \varepsilon - \sin x \cdot \sin \varepsilon\right)} - \cos x \]
      2. associate--l-61.8%

        \[\leadsto \color{blue}{\cos x \cdot \cos \varepsilon - \left(\sin x \cdot \sin \varepsilon + \cos x\right)} \]
      3. fma-neg61.9%

        \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon, -\left(\sin x \cdot \sin \varepsilon + \cos x\right)\right)} \]
      4. fma-def61.9%

        \[\leadsto \mathsf{fma}\left(\cos x, \cos \varepsilon, -\color{blue}{\mathsf{fma}\left(\sin x, \sin \varepsilon, \cos x\right)}\right) \]
    3. Applied egg-rr61.9%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon, -\mathsf{fma}\left(\sin x, \sin \varepsilon, \cos x\right)\right)} \]
    4. Taylor expanded in x around inf 61.8%

      \[\leadsto \color{blue}{\cos \varepsilon \cdot \cos x - \left(\cos x + \sin \varepsilon \cdot \sin x\right)} \]
    5. Step-by-step derivation
      1. associate--r+99.1%

        \[\leadsto \color{blue}{\left(\cos \varepsilon \cdot \cos x - \cos x\right) - \sin \varepsilon \cdot \sin x} \]
      2. *-commutative99.1%

        \[\leadsto \left(\color{blue}{\cos x \cdot \cos \varepsilon} - \cos x\right) - \sin \varepsilon \cdot \sin x \]
      3. *-rgt-identity99.1%

        \[\leadsto \left(\cos x \cdot \cos \varepsilon - \color{blue}{\cos x \cdot 1}\right) - \sin \varepsilon \cdot \sin x \]
      4. distribute-lft-out--99.1%

        \[\leadsto \color{blue}{\cos x \cdot \left(\cos \varepsilon - 1\right)} - \sin \varepsilon \cdot \sin x \]
      5. sub-neg99.1%

        \[\leadsto \cos x \cdot \color{blue}{\left(\cos \varepsilon + \left(-1\right)\right)} - \sin \varepsilon \cdot \sin x \]
      6. metadata-eval99.1%

        \[\leadsto \cos x \cdot \left(\cos \varepsilon + \color{blue}{-1}\right) - \sin \varepsilon \cdot \sin x \]
      7. *-commutative99.1%

        \[\leadsto \cos x \cdot \left(\cos \varepsilon + -1\right) - \color{blue}{\sin x \cdot \sin \varepsilon} \]
      8. fma-neg99.1%

        \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon + -1, -\sin x \cdot \sin \varepsilon\right)} \]
      9. +-commutative99.1%

        \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{-1 + \cos \varepsilon}, -\sin x \cdot \sin \varepsilon\right) \]
      10. distribute-rgt-neg-in99.1%

        \[\leadsto \mathsf{fma}\left(\cos x, -1 + \cos \varepsilon, \color{blue}{\sin x \cdot \left(-\sin \varepsilon\right)}\right) \]
    6. Simplified99.1%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, -1 + \cos \varepsilon, \sin x \cdot \left(-\sin \varepsilon\right)\right)} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification99.4%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -2.75 \cdot 10^{-8}:\\ \;\;\;\;\left(\cos x \cdot \cos \varepsilon - \cos x\right) - \sin \varepsilon \cdot \sin x\\ \mathbf{elif}\;x \leq 4.4 \cdot 10^{-41}:\\ \;\;\;\;\left(\sin \left(\varepsilon \cdot 0.5\right) + x \cdot \cos \left(\varepsilon \cdot 0.5\right)\right) \cdot \left(\sin \left(\varepsilon \cdot 0.5\right) \cdot -2\right)\\ \mathbf{else}:\\ \;\;\;\;\mathsf{fma}\left(\cos x, \cos \varepsilon + -1, \sin \varepsilon \cdot \left(-\sin x\right)\right)\\ \end{array} \]

Alternative 4: 99.1% accurate, 0.5× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \sin \left(\varepsilon \cdot 0.5\right)\\ \mathbf{if}\;x \leq -3.5 \cdot 10^{-8} \lor \neg \left(x \leq 2.3 \cdot 10^{-40}\right):\\ \;\;\;\;\cos x \cdot \left(\cos \varepsilon + -1\right) - \sin \varepsilon \cdot \sin x\\ \mathbf{else}:\\ \;\;\;\;\left(t_0 + x \cdot \cos \left(\varepsilon \cdot 0.5\right)\right) \cdot \left(t_0 \cdot -2\right)\\ \end{array} \end{array} \]
(FPCore (x eps)
 :precision binary64
 (let* ((t_0 (sin (* eps 0.5))))
   (if (or (<= x -3.5e-8) (not (<= x 2.3e-40)))
     (- (* (cos x) (+ (cos eps) -1.0)) (* (sin eps) (sin x)))
     (* (+ t_0 (* x (cos (* eps 0.5)))) (* t_0 -2.0)))))
double code(double x, double eps) {
	double t_0 = sin((eps * 0.5));
	double tmp;
	if ((x <= -3.5e-8) || !(x <= 2.3e-40)) {
		tmp = (cos(x) * (cos(eps) + -1.0)) - (sin(eps) * sin(x));
	} else {
		tmp = (t_0 + (x * cos((eps * 0.5)))) * (t_0 * -2.0);
	}
	return tmp;
}
real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    real(8) :: t_0
    real(8) :: tmp
    t_0 = sin((eps * 0.5d0))
    if ((x <= (-3.5d-8)) .or. (.not. (x <= 2.3d-40))) then
        tmp = (cos(x) * (cos(eps) + (-1.0d0))) - (sin(eps) * sin(x))
    else
        tmp = (t_0 + (x * cos((eps * 0.5d0)))) * (t_0 * (-2.0d0))
    end if
    code = tmp
end function
public static double code(double x, double eps) {
	double t_0 = Math.sin((eps * 0.5));
	double tmp;
	if ((x <= -3.5e-8) || !(x <= 2.3e-40)) {
		tmp = (Math.cos(x) * (Math.cos(eps) + -1.0)) - (Math.sin(eps) * Math.sin(x));
	} else {
		tmp = (t_0 + (x * Math.cos((eps * 0.5)))) * (t_0 * -2.0);
	}
	return tmp;
}
def code(x, eps):
	t_0 = math.sin((eps * 0.5))
	tmp = 0
	if (x <= -3.5e-8) or not (x <= 2.3e-40):
		tmp = (math.cos(x) * (math.cos(eps) + -1.0)) - (math.sin(eps) * math.sin(x))
	else:
		tmp = (t_0 + (x * math.cos((eps * 0.5)))) * (t_0 * -2.0)
	return tmp
function code(x, eps)
	t_0 = sin(Float64(eps * 0.5))
	tmp = 0.0
	if ((x <= -3.5e-8) || !(x <= 2.3e-40))
		tmp = Float64(Float64(cos(x) * Float64(cos(eps) + -1.0)) - Float64(sin(eps) * sin(x)));
	else
		tmp = Float64(Float64(t_0 + Float64(x * cos(Float64(eps * 0.5)))) * Float64(t_0 * -2.0));
	end
	return tmp
end
function tmp_2 = code(x, eps)
	t_0 = sin((eps * 0.5));
	tmp = 0.0;
	if ((x <= -3.5e-8) || ~((x <= 2.3e-40)))
		tmp = (cos(x) * (cos(eps) + -1.0)) - (sin(eps) * sin(x));
	else
		tmp = (t_0 + (x * cos((eps * 0.5)))) * (t_0 * -2.0);
	end
	tmp_2 = tmp;
end
code[x_, eps_] := Block[{t$95$0 = N[Sin[N[(eps * 0.5), $MachinePrecision]], $MachinePrecision]}, If[Or[LessEqual[x, -3.5e-8], N[Not[LessEqual[x, 2.3e-40]], $MachinePrecision]], N[(N[(N[Cos[x], $MachinePrecision] * N[(N[Cos[eps], $MachinePrecision] + -1.0), $MachinePrecision]), $MachinePrecision] - N[(N[Sin[eps], $MachinePrecision] * N[Sin[x], $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(N[(t$95$0 + N[(x * N[Cos[N[(eps * 0.5), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] * N[(t$95$0 * -2.0), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \sin \left(\varepsilon \cdot 0.5\right)\\
\mathbf{if}\;x \leq -3.5 \cdot 10^{-8} \lor \neg \left(x \leq 2.3 \cdot 10^{-40}\right):\\
\;\;\;\;\cos x \cdot \left(\cos \varepsilon + -1\right) - \sin \varepsilon \cdot \sin x\\

\mathbf{else}:\\
\;\;\;\;\left(t_0 + x \cdot \cos \left(\varepsilon \cdot 0.5\right)\right) \cdot \left(t_0 \cdot -2\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < -3.50000000000000024e-8 or 2.3e-40 < x

    1. Initial program 9.8%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Step-by-step derivation
      1. cos-sum59.2%

        \[\leadsto \color{blue}{\left(\cos x \cdot \cos \varepsilon - \sin x \cdot \sin \varepsilon\right)} - \cos x \]
      2. associate--l-59.3%

        \[\leadsto \color{blue}{\cos x \cdot \cos \varepsilon - \left(\sin x \cdot \sin \varepsilon + \cos x\right)} \]
      3. fma-neg59.3%

        \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon, -\left(\sin x \cdot \sin \varepsilon + \cos x\right)\right)} \]
      4. fma-def59.3%

        \[\leadsto \mathsf{fma}\left(\cos x, \cos \varepsilon, -\color{blue}{\mathsf{fma}\left(\sin x, \sin \varepsilon, \cos x\right)}\right) \]
    3. Applied egg-rr59.3%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\cos x, \cos \varepsilon, -\mathsf{fma}\left(\sin x, \sin \varepsilon, \cos x\right)\right)} \]
    4. Taylor expanded in x around inf 59.3%

      \[\leadsto \color{blue}{\cos \varepsilon \cdot \cos x - \left(\cos x + \sin \varepsilon \cdot \sin x\right)} \]
    5. Step-by-step derivation
      1. associate--r+99.2%

        \[\leadsto \color{blue}{\left(\cos \varepsilon \cdot \cos x - \cos x\right) - \sin \varepsilon \cdot \sin x} \]
      2. *-commutative99.2%

        \[\leadsto \left(\color{blue}{\cos x \cdot \cos \varepsilon} - \cos x\right) - \sin \varepsilon \cdot \sin x \]
      3. *-rgt-identity99.2%

        \[\leadsto \left(\cos x \cdot \cos \varepsilon - \color{blue}{\cos x \cdot 1}\right) - \sin \varepsilon \cdot \sin x \]
      4. distribute-lft-out--99.1%

        \[\leadsto \color{blue}{\cos x \cdot \left(\cos \varepsilon - 1\right)} - \sin \varepsilon \cdot \sin x \]
      5. sub-neg99.1%

        \[\leadsto \cos x \cdot \color{blue}{\left(\cos \varepsilon + \left(-1\right)\right)} - \sin \varepsilon \cdot \sin x \]
      6. metadata-eval99.1%

        \[\leadsto \cos x \cdot \left(\cos \varepsilon + \color{blue}{-1}\right) - \sin \varepsilon \cdot \sin x \]
      7. +-commutative99.1%

        \[\leadsto \cos x \cdot \color{blue}{\left(-1 + \cos \varepsilon\right)} - \sin \varepsilon \cdot \sin x \]
      8. *-commutative99.1%

        \[\leadsto \cos x \cdot \left(-1 + \cos \varepsilon\right) - \color{blue}{\sin x \cdot \sin \varepsilon} \]
    6. Simplified99.1%

      \[\leadsto \color{blue}{\cos x \cdot \left(-1 + \cos \varepsilon\right) - \sin x \cdot \sin \varepsilon} \]

    if -3.50000000000000024e-8 < x < 2.3e-40

    1. Initial program 69.8%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Step-by-step derivation
      1. diff-cos90.9%

        \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\frac{\left(x + \varepsilon\right) - x}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right)} \]
      2. div-inv90.9%

        \[\leadsto -2 \cdot \left(\sin \color{blue}{\left(\left(\left(x + \varepsilon\right) - x\right) \cdot \frac{1}{2}\right)} \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      3. associate--l+90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\color{blue}{\left(x + \left(\varepsilon - x\right)\right)} \cdot \frac{1}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      4. metadata-eval90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot \color{blue}{0.5}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      5. div-inv90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \color{blue}{\left(\left(\left(x + \varepsilon\right) + x\right) \cdot \frac{1}{2}\right)}\right) \]
      6. +-commutative90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\color{blue}{\left(\varepsilon + x\right)} + x\right) \cdot \frac{1}{2}\right)\right) \]
      7. associate-+l+90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\color{blue}{\left(\varepsilon + \left(x + x\right)\right)} \cdot \frac{1}{2}\right)\right) \]
      8. metadata-eval90.9%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot \color{blue}{0.5}\right)\right) \]
    3. Applied egg-rr90.9%

      \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)\right)} \]
    4. Step-by-step derivation
      1. associate-*r*90.9%

        \[\leadsto \color{blue}{\left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)} \]
      2. *-commutative90.9%

        \[\leadsto \color{blue}{\sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right)} \]
      3. *-commutative90.9%

        \[\leadsto \sin \color{blue}{\left(0.5 \cdot \left(\varepsilon + \left(x + x\right)\right)\right)} \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      4. +-commutative90.9%

        \[\leadsto \sin \left(0.5 \cdot \color{blue}{\left(\left(x + x\right) + \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      5. count-290.9%

        \[\leadsto \sin \left(0.5 \cdot \left(\color{blue}{2 \cdot x} + \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      6. fma-def90.9%

        \[\leadsto \sin \left(0.5 \cdot \color{blue}{\mathsf{fma}\left(2, x, \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      7. sub-neg90.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(\varepsilon + \left(-x\right)\right)}\right) \cdot 0.5\right)\right) \]
      8. mul-1-neg90.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon + \color{blue}{-1 \cdot x}\right)\right) \cdot 0.5\right)\right) \]
      9. +-commutative90.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(-1 \cdot x + \varepsilon\right)}\right) \cdot 0.5\right)\right) \]
      10. associate-+r+98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(\left(x + -1 \cdot x\right) + \varepsilon\right)} \cdot 0.5\right)\right) \]
      11. mul-1-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\left(x + \color{blue}{\left(-x\right)}\right) + \varepsilon\right) \cdot 0.5\right)\right) \]
      12. sub-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{\left(x - x\right)} + \varepsilon\right) \cdot 0.5\right)\right) \]
      13. +-inverses98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{0} + \varepsilon\right) \cdot 0.5\right)\right) \]
      14. remove-double-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \color{blue}{\left(-\left(-\varepsilon\right)\right)}\right) \cdot 0.5\right)\right) \]
      15. mul-1-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \left(-\color{blue}{-1 \cdot \varepsilon}\right)\right) \cdot 0.5\right)\right) \]
      16. sub-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(0 - -1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
      17. neg-sub098.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(--1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
      18. mul-1-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(-\color{blue}{\left(-\varepsilon\right)}\right) \cdot 0.5\right)\right) \]
      19. remove-double-neg98.9%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\varepsilon} \cdot 0.5\right)\right) \]
    5. Simplified98.9%

      \[\leadsto \color{blue}{\sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\varepsilon \cdot 0.5\right)\right)} \]
    6. Taylor expanded in x around 0 99.6%

      \[\leadsto \color{blue}{\left(\sin \left(0.5 \cdot \varepsilon\right) + x \cdot \cos \left(0.5 \cdot \varepsilon\right)\right)} \cdot \left(-2 \cdot \sin \left(\varepsilon \cdot 0.5\right)\right) \]
  3. Recombined 2 regimes into one program.
  4. Final simplification99.3%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -3.5 \cdot 10^{-8} \lor \neg \left(x \leq 2.3 \cdot 10^{-40}\right):\\ \;\;\;\;\cos x \cdot \left(\cos \varepsilon + -1\right) - \sin \varepsilon \cdot \sin x\\ \mathbf{else}:\\ \;\;\;\;\left(\sin \left(\varepsilon \cdot 0.5\right) + x \cdot \cos \left(\varepsilon \cdot 0.5\right)\right) \cdot \left(\sin \left(\varepsilon \cdot 0.5\right) \cdot -2\right)\\ \end{array} \]

Alternative 5: 66.0% accurate, 0.5× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;\cos \left(x + \varepsilon\right) - \cos x \leq -1 \cdot 10^{-16}:\\ \;\;\;\;\cos \varepsilon - \cos x\\ \mathbf{else}:\\ \;\;\;\;\varepsilon \cdot \left(-\sin x\right)\\ \end{array} \end{array} \]
(FPCore (x eps)
 :precision binary64
 (if (<= (- (cos (+ x eps)) (cos x)) -1e-16)
   (- (cos eps) (cos x))
   (* eps (- (sin x)))))
double code(double x, double eps) {
	double tmp;
	if ((cos((x + eps)) - cos(x)) <= -1e-16) {
		tmp = cos(eps) - cos(x);
	} else {
		tmp = eps * -sin(x);
	}
	return tmp;
}
real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    real(8) :: tmp
    if ((cos((x + eps)) - cos(x)) <= (-1d-16)) then
        tmp = cos(eps) - cos(x)
    else
        tmp = eps * -sin(x)
    end if
    code = tmp
end function
public static double code(double x, double eps) {
	double tmp;
	if ((Math.cos((x + eps)) - Math.cos(x)) <= -1e-16) {
		tmp = Math.cos(eps) - Math.cos(x);
	} else {
		tmp = eps * -Math.sin(x);
	}
	return tmp;
}
def code(x, eps):
	tmp = 0
	if (math.cos((x + eps)) - math.cos(x)) <= -1e-16:
		tmp = math.cos(eps) - math.cos(x)
	else:
		tmp = eps * -math.sin(x)
	return tmp
function code(x, eps)
	tmp = 0.0
	if (Float64(cos(Float64(x + eps)) - cos(x)) <= -1e-16)
		tmp = Float64(cos(eps) - cos(x));
	else
		tmp = Float64(eps * Float64(-sin(x)));
	end
	return tmp
end
function tmp_2 = code(x, eps)
	tmp = 0.0;
	if ((cos((x + eps)) - cos(x)) <= -1e-16)
		tmp = cos(eps) - cos(x);
	else
		tmp = eps * -sin(x);
	end
	tmp_2 = tmp;
end
code[x_, eps_] := If[LessEqual[N[(N[Cos[N[(x + eps), $MachinePrecision]], $MachinePrecision] - N[Cos[x], $MachinePrecision]), $MachinePrecision], -1e-16], N[(N[Cos[eps], $MachinePrecision] - N[Cos[x], $MachinePrecision]), $MachinePrecision], N[(eps * (-N[Sin[x], $MachinePrecision])), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;\cos \left(x + \varepsilon\right) - \cos x \leq -1 \cdot 10^{-16}:\\
\;\;\;\;\cos \varepsilon - \cos x\\

\mathbf{else}:\\
\;\;\;\;\varepsilon \cdot \left(-\sin x\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (-.f64 (cos.f64 (+.f64 x eps)) (cos.f64 x)) < -9.9999999999999998e-17

    1. Initial program 75.9%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in x around 0 76.2%

      \[\leadsto \color{blue}{\cos \varepsilon} - \cos x \]

    if -9.9999999999999998e-17 < (-.f64 (cos.f64 (+.f64 x eps)) (cos.f64 x))

    1. Initial program 18.4%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in eps around 0 56.4%

      \[\leadsto \color{blue}{-1 \cdot \left(\varepsilon \cdot \sin x\right)} \]
    3. Step-by-step derivation
      1. mul-1-neg56.4%

        \[\leadsto \color{blue}{-\varepsilon \cdot \sin x} \]
      2. *-commutative56.4%

        \[\leadsto -\color{blue}{\sin x \cdot \varepsilon} \]
      3. distribute-rgt-neg-in56.4%

        \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]
    4. Simplified56.4%

      \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification62.9%

    \[\leadsto \begin{array}{l} \mathbf{if}\;\cos \left(x + \varepsilon\right) - \cos x \leq -1 \cdot 10^{-16}:\\ \;\;\;\;\cos \varepsilon - \cos x\\ \mathbf{else}:\\ \;\;\;\;\varepsilon \cdot \left(-\sin x\right)\\ \end{array} \]

Alternative 6: 76.0% accurate, 0.7× speedup?

\[\begin{array}{l} \\ \left(\sin \left(\varepsilon \cdot 0.5\right) \cdot -2\right) \cdot \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \end{array} \]
(FPCore (x eps)
 :precision binary64
 (* (* (sin (* eps 0.5)) -2.0) (sin (* 0.5 (fma 2.0 x eps)))))
double code(double x, double eps) {
	return (sin((eps * 0.5)) * -2.0) * sin((0.5 * fma(2.0, x, eps)));
}
function code(x, eps)
	return Float64(Float64(sin(Float64(eps * 0.5)) * -2.0) * sin(Float64(0.5 * fma(2.0, x, eps))))
end
code[x_, eps_] := N[(N[(N[Sin[N[(eps * 0.5), $MachinePrecision]], $MachinePrecision] * -2.0), $MachinePrecision] * N[Sin[N[(0.5 * N[(2.0 * x + eps), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\left(\sin \left(\varepsilon \cdot 0.5\right) \cdot -2\right) \cdot \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right)
\end{array}
Derivation
  1. Initial program 37.2%

    \[\cos \left(x + \varepsilon\right) - \cos x \]
  2. Step-by-step derivation
    1. diff-cos47.2%

      \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\frac{\left(x + \varepsilon\right) - x}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right)} \]
    2. div-inv47.2%

      \[\leadsto -2 \cdot \left(\sin \color{blue}{\left(\left(\left(x + \varepsilon\right) - x\right) \cdot \frac{1}{2}\right)} \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
    3. associate--l+47.2%

      \[\leadsto -2 \cdot \left(\sin \left(\color{blue}{\left(x + \left(\varepsilon - x\right)\right)} \cdot \frac{1}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
    4. metadata-eval47.2%

      \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot \color{blue}{0.5}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
    5. div-inv47.2%

      \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \color{blue}{\left(\left(\left(x + \varepsilon\right) + x\right) \cdot \frac{1}{2}\right)}\right) \]
    6. +-commutative47.2%

      \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\color{blue}{\left(\varepsilon + x\right)} + x\right) \cdot \frac{1}{2}\right)\right) \]
    7. associate-+l+47.3%

      \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\color{blue}{\left(\varepsilon + \left(x + x\right)\right)} \cdot \frac{1}{2}\right)\right) \]
    8. metadata-eval47.3%

      \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot \color{blue}{0.5}\right)\right) \]
  3. Applied egg-rr47.3%

    \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)\right)} \]
  4. Step-by-step derivation
    1. associate-*r*47.4%

      \[\leadsto \color{blue}{\left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)} \]
    2. *-commutative47.4%

      \[\leadsto \color{blue}{\sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right)} \]
    3. *-commutative47.4%

      \[\leadsto \sin \color{blue}{\left(0.5 \cdot \left(\varepsilon + \left(x + x\right)\right)\right)} \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
    4. +-commutative47.4%

      \[\leadsto \sin \left(0.5 \cdot \color{blue}{\left(\left(x + x\right) + \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
    5. count-247.4%

      \[\leadsto \sin \left(0.5 \cdot \left(\color{blue}{2 \cdot x} + \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
    6. fma-def47.4%

      \[\leadsto \sin \left(0.5 \cdot \color{blue}{\mathsf{fma}\left(2, x, \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
    7. sub-neg47.4%

      \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(\varepsilon + \left(-x\right)\right)}\right) \cdot 0.5\right)\right) \]
    8. mul-1-neg47.4%

      \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon + \color{blue}{-1 \cdot x}\right)\right) \cdot 0.5\right)\right) \]
    9. +-commutative47.4%

      \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(-1 \cdot x + \varepsilon\right)}\right) \cdot 0.5\right)\right) \]
    10. associate-+r+74.0%

      \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(\left(x + -1 \cdot x\right) + \varepsilon\right)} \cdot 0.5\right)\right) \]
    11. mul-1-neg74.0%

      \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\left(x + \color{blue}{\left(-x\right)}\right) + \varepsilon\right) \cdot 0.5\right)\right) \]
    12. sub-neg74.0%

      \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{\left(x - x\right)} + \varepsilon\right) \cdot 0.5\right)\right) \]
    13. +-inverses74.0%

      \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{0} + \varepsilon\right) \cdot 0.5\right)\right) \]
    14. remove-double-neg74.0%

      \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \color{blue}{\left(-\left(-\varepsilon\right)\right)}\right) \cdot 0.5\right)\right) \]
    15. mul-1-neg74.0%

      \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \left(-\color{blue}{-1 \cdot \varepsilon}\right)\right) \cdot 0.5\right)\right) \]
    16. sub-neg74.0%

      \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(0 - -1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
    17. neg-sub074.0%

      \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(--1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
    18. mul-1-neg74.0%

      \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(-\color{blue}{\left(-\varepsilon\right)}\right) \cdot 0.5\right)\right) \]
    19. remove-double-neg74.0%

      \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\varepsilon} \cdot 0.5\right)\right) \]
  5. Simplified74.0%

    \[\leadsto \color{blue}{\sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\varepsilon \cdot 0.5\right)\right)} \]
  6. Final simplification74.0%

    \[\leadsto \left(\sin \left(\varepsilon \cdot 0.5\right) \cdot -2\right) \cdot \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \]

Alternative 7: 69.6% accurate, 0.9× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \sin x \cdot \left(\sin \left(\varepsilon \cdot 0.5\right) \cdot -2\right)\\ \mathbf{if}\;x \leq -7.6 \cdot 10^{-9}:\\ \;\;\;\;t_0\\ \mathbf{elif}\;x \leq -7.2 \cdot 10^{-63}:\\ \;\;\;\;-1 + \left(\cos \varepsilon - x \cdot \sin \varepsilon\right)\\ \mathbf{elif}\;x \leq -8.2 \cdot 10^{-91}:\\ \;\;\;\;-0.5 \cdot {\varepsilon}^{2} + x \cdot \left(0.16666666666666666 \cdot {\varepsilon}^{3} - \varepsilon\right)\\ \mathbf{elif}\;x \leq 1.8 \cdot 10^{-9}:\\ \;\;\;\;\tan \left(\frac{\varepsilon}{2}\right) \cdot \left(-\sin \varepsilon\right)\\ \mathbf{else}:\\ \;\;\;\;t_0\\ \end{array} \end{array} \]
(FPCore (x eps)
 :precision binary64
 (let* ((t_0 (* (sin x) (* (sin (* eps 0.5)) -2.0))))
   (if (<= x -7.6e-9)
     t_0
     (if (<= x -7.2e-63)
       (+ -1.0 (- (cos eps) (* x (sin eps))))
       (if (<= x -8.2e-91)
         (+
          (* -0.5 (pow eps 2.0))
          (* x (- (* 0.16666666666666666 (pow eps 3.0)) eps)))
         (if (<= x 1.8e-9) (* (tan (/ eps 2.0)) (- (sin eps))) t_0))))))
double code(double x, double eps) {
	double t_0 = sin(x) * (sin((eps * 0.5)) * -2.0);
	double tmp;
	if (x <= -7.6e-9) {
		tmp = t_0;
	} else if (x <= -7.2e-63) {
		tmp = -1.0 + (cos(eps) - (x * sin(eps)));
	} else if (x <= -8.2e-91) {
		tmp = (-0.5 * pow(eps, 2.0)) + (x * ((0.16666666666666666 * pow(eps, 3.0)) - eps));
	} else if (x <= 1.8e-9) {
		tmp = tan((eps / 2.0)) * -sin(eps);
	} else {
		tmp = t_0;
	}
	return tmp;
}
real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    real(8) :: t_0
    real(8) :: tmp
    t_0 = sin(x) * (sin((eps * 0.5d0)) * (-2.0d0))
    if (x <= (-7.6d-9)) then
        tmp = t_0
    else if (x <= (-7.2d-63)) then
        tmp = (-1.0d0) + (cos(eps) - (x * sin(eps)))
    else if (x <= (-8.2d-91)) then
        tmp = ((-0.5d0) * (eps ** 2.0d0)) + (x * ((0.16666666666666666d0 * (eps ** 3.0d0)) - eps))
    else if (x <= 1.8d-9) then
        tmp = tan((eps / 2.0d0)) * -sin(eps)
    else
        tmp = t_0
    end if
    code = tmp
end function
public static double code(double x, double eps) {
	double t_0 = Math.sin(x) * (Math.sin((eps * 0.5)) * -2.0);
	double tmp;
	if (x <= -7.6e-9) {
		tmp = t_0;
	} else if (x <= -7.2e-63) {
		tmp = -1.0 + (Math.cos(eps) - (x * Math.sin(eps)));
	} else if (x <= -8.2e-91) {
		tmp = (-0.5 * Math.pow(eps, 2.0)) + (x * ((0.16666666666666666 * Math.pow(eps, 3.0)) - eps));
	} else if (x <= 1.8e-9) {
		tmp = Math.tan((eps / 2.0)) * -Math.sin(eps);
	} else {
		tmp = t_0;
	}
	return tmp;
}
def code(x, eps):
	t_0 = math.sin(x) * (math.sin((eps * 0.5)) * -2.0)
	tmp = 0
	if x <= -7.6e-9:
		tmp = t_0
	elif x <= -7.2e-63:
		tmp = -1.0 + (math.cos(eps) - (x * math.sin(eps)))
	elif x <= -8.2e-91:
		tmp = (-0.5 * math.pow(eps, 2.0)) + (x * ((0.16666666666666666 * math.pow(eps, 3.0)) - eps))
	elif x <= 1.8e-9:
		tmp = math.tan((eps / 2.0)) * -math.sin(eps)
	else:
		tmp = t_0
	return tmp
function code(x, eps)
	t_0 = Float64(sin(x) * Float64(sin(Float64(eps * 0.5)) * -2.0))
	tmp = 0.0
	if (x <= -7.6e-9)
		tmp = t_0;
	elseif (x <= -7.2e-63)
		tmp = Float64(-1.0 + Float64(cos(eps) - Float64(x * sin(eps))));
	elseif (x <= -8.2e-91)
		tmp = Float64(Float64(-0.5 * (eps ^ 2.0)) + Float64(x * Float64(Float64(0.16666666666666666 * (eps ^ 3.0)) - eps)));
	elseif (x <= 1.8e-9)
		tmp = Float64(tan(Float64(eps / 2.0)) * Float64(-sin(eps)));
	else
		tmp = t_0;
	end
	return tmp
end
function tmp_2 = code(x, eps)
	t_0 = sin(x) * (sin((eps * 0.5)) * -2.0);
	tmp = 0.0;
	if (x <= -7.6e-9)
		tmp = t_0;
	elseif (x <= -7.2e-63)
		tmp = -1.0 + (cos(eps) - (x * sin(eps)));
	elseif (x <= -8.2e-91)
		tmp = (-0.5 * (eps ^ 2.0)) + (x * ((0.16666666666666666 * (eps ^ 3.0)) - eps));
	elseif (x <= 1.8e-9)
		tmp = tan((eps / 2.0)) * -sin(eps);
	else
		tmp = t_0;
	end
	tmp_2 = tmp;
end
code[x_, eps_] := Block[{t$95$0 = N[(N[Sin[x], $MachinePrecision] * N[(N[Sin[N[(eps * 0.5), $MachinePrecision]], $MachinePrecision] * -2.0), $MachinePrecision]), $MachinePrecision]}, If[LessEqual[x, -7.6e-9], t$95$0, If[LessEqual[x, -7.2e-63], N[(-1.0 + N[(N[Cos[eps], $MachinePrecision] - N[(x * N[Sin[eps], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], If[LessEqual[x, -8.2e-91], N[(N[(-0.5 * N[Power[eps, 2.0], $MachinePrecision]), $MachinePrecision] + N[(x * N[(N[(0.16666666666666666 * N[Power[eps, 3.0], $MachinePrecision]), $MachinePrecision] - eps), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], If[LessEqual[x, 1.8e-9], N[(N[Tan[N[(eps / 2.0), $MachinePrecision]], $MachinePrecision] * (-N[Sin[eps], $MachinePrecision])), $MachinePrecision], t$95$0]]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \sin x \cdot \left(\sin \left(\varepsilon \cdot 0.5\right) \cdot -2\right)\\
\mathbf{if}\;x \leq -7.6 \cdot 10^{-9}:\\
\;\;\;\;t_0\\

\mathbf{elif}\;x \leq -7.2 \cdot 10^{-63}:\\
\;\;\;\;-1 + \left(\cos \varepsilon - x \cdot \sin \varepsilon\right)\\

\mathbf{elif}\;x \leq -8.2 \cdot 10^{-91}:\\
\;\;\;\;-0.5 \cdot {\varepsilon}^{2} + x \cdot \left(0.16666666666666666 \cdot {\varepsilon}^{3} - \varepsilon\right)\\

\mathbf{elif}\;x \leq 1.8 \cdot 10^{-9}:\\
\;\;\;\;\tan \left(\frac{\varepsilon}{2}\right) \cdot \left(-\sin \varepsilon\right)\\

\mathbf{else}:\\
\;\;\;\;t_0\\


\end{array}
\end{array}
Derivation
  1. Split input into 4 regimes
  2. if x < -7.60000000000000023e-9 or 1.8e-9 < x

    1. Initial program 6.6%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Step-by-step derivation
      1. diff-cos7.3%

        \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\frac{\left(x + \varepsilon\right) - x}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right)} \]
      2. div-inv7.3%

        \[\leadsto -2 \cdot \left(\sin \color{blue}{\left(\left(\left(x + \varepsilon\right) - x\right) \cdot \frac{1}{2}\right)} \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      3. associate--l+7.3%

        \[\leadsto -2 \cdot \left(\sin \left(\color{blue}{\left(x + \left(\varepsilon - x\right)\right)} \cdot \frac{1}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      4. metadata-eval7.3%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot \color{blue}{0.5}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      5. div-inv7.3%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \color{blue}{\left(\left(\left(x + \varepsilon\right) + x\right) \cdot \frac{1}{2}\right)}\right) \]
      6. +-commutative7.3%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\color{blue}{\left(\varepsilon + x\right)} + x\right) \cdot \frac{1}{2}\right)\right) \]
      7. associate-+l+7.6%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\color{blue}{\left(\varepsilon + \left(x + x\right)\right)} \cdot \frac{1}{2}\right)\right) \]
      8. metadata-eval7.6%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot \color{blue}{0.5}\right)\right) \]
    3. Applied egg-rr7.6%

      \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)\right)} \]
    4. Step-by-step derivation
      1. associate-*r*7.6%

        \[\leadsto \color{blue}{\left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)} \]
      2. *-commutative7.6%

        \[\leadsto \color{blue}{\sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right)} \]
      3. *-commutative7.6%

        \[\leadsto \sin \color{blue}{\left(0.5 \cdot \left(\varepsilon + \left(x + x\right)\right)\right)} \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      4. +-commutative7.6%

        \[\leadsto \sin \left(0.5 \cdot \color{blue}{\left(\left(x + x\right) + \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      5. count-27.6%

        \[\leadsto \sin \left(0.5 \cdot \left(\color{blue}{2 \cdot x} + \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      6. fma-def7.6%

        \[\leadsto \sin \left(0.5 \cdot \color{blue}{\mathsf{fma}\left(2, x, \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      7. sub-neg7.6%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(\varepsilon + \left(-x\right)\right)}\right) \cdot 0.5\right)\right) \]
      8. mul-1-neg7.6%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon + \color{blue}{-1 \cdot x}\right)\right) \cdot 0.5\right)\right) \]
      9. +-commutative7.6%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(-1 \cdot x + \varepsilon\right)}\right) \cdot 0.5\right)\right) \]
      10. associate-+r+51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(\left(x + -1 \cdot x\right) + \varepsilon\right)} \cdot 0.5\right)\right) \]
      11. mul-1-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\left(x + \color{blue}{\left(-x\right)}\right) + \varepsilon\right) \cdot 0.5\right)\right) \]
      12. sub-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{\left(x - x\right)} + \varepsilon\right) \cdot 0.5\right)\right) \]
      13. +-inverses51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{0} + \varepsilon\right) \cdot 0.5\right)\right) \]
      14. remove-double-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \color{blue}{\left(-\left(-\varepsilon\right)\right)}\right) \cdot 0.5\right)\right) \]
      15. mul-1-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \left(-\color{blue}{-1 \cdot \varepsilon}\right)\right) \cdot 0.5\right)\right) \]
      16. sub-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(0 - -1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
      17. neg-sub051.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(--1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
      18. mul-1-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(-\color{blue}{\left(-\varepsilon\right)}\right) \cdot 0.5\right)\right) \]
      19. remove-double-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\varepsilon} \cdot 0.5\right)\right) \]
    5. Simplified51.0%

      \[\leadsto \color{blue}{\sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\varepsilon \cdot 0.5\right)\right)} \]
    6. Taylor expanded in eps around 0 50.8%

      \[\leadsto \color{blue}{\sin x} \cdot \left(-2 \cdot \sin \left(\varepsilon \cdot 0.5\right)\right) \]

    if -7.60000000000000023e-9 < x < -7.20000000000000016e-63

    1. Initial program 82.3%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Step-by-step derivation
      1. log1p-expm1-u82.0%

        \[\leadsto \color{blue}{\mathsf{log1p}\left(\mathsf{expm1}\left(\cos \left(x + \varepsilon\right) - \cos x\right)\right)} \]
    3. Applied egg-rr82.0%

      \[\leadsto \color{blue}{\mathsf{log1p}\left(\mathsf{expm1}\left(\cos \left(x + \varepsilon\right) - \cos x\right)\right)} \]
    4. Taylor expanded in x around 0 87.7%

      \[\leadsto \color{blue}{\left(\cos \varepsilon + -1 \cdot \left(x \cdot \sin \varepsilon\right)\right) - 1} \]
    5. Step-by-step derivation
      1. sub-neg87.7%

        \[\leadsto \color{blue}{\left(\cos \varepsilon + -1 \cdot \left(x \cdot \sin \varepsilon\right)\right) + \left(-1\right)} \]
      2. metadata-eval87.7%

        \[\leadsto \left(\cos \varepsilon + -1 \cdot \left(x \cdot \sin \varepsilon\right)\right) + \color{blue}{-1} \]
      3. +-commutative87.7%

        \[\leadsto \color{blue}{-1 + \left(\cos \varepsilon + -1 \cdot \left(x \cdot \sin \varepsilon\right)\right)} \]
      4. mul-1-neg87.7%

        \[\leadsto -1 + \left(\cos \varepsilon + \color{blue}{\left(-x \cdot \sin \varepsilon\right)}\right) \]
      5. unsub-neg87.7%

        \[\leadsto -1 + \color{blue}{\left(\cos \varepsilon - x \cdot \sin \varepsilon\right)} \]
    6. Simplified87.7%

      \[\leadsto \color{blue}{-1 + \left(\cos \varepsilon - x \cdot \sin \varepsilon\right)} \]

    if -7.20000000000000016e-63 < x < -8.20000000000000048e-91

    1. Initial program 29.3%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in eps around 0 99.8%

      \[\leadsto \color{blue}{-1 \cdot \left(\varepsilon \cdot \sin x\right) + \left(-0.5 \cdot \left({\varepsilon}^{2} \cdot \cos x\right) + 0.16666666666666666 \cdot \left({\varepsilon}^{3} \cdot \sin x\right)\right)} \]
    3. Step-by-step derivation
      1. associate-+r+99.8%

        \[\leadsto \color{blue}{\left(-1 \cdot \left(\varepsilon \cdot \sin x\right) + -0.5 \cdot \left({\varepsilon}^{2} \cdot \cos x\right)\right) + 0.16666666666666666 \cdot \left({\varepsilon}^{3} \cdot \sin x\right)} \]
      2. +-commutative99.8%

        \[\leadsto \color{blue}{\left(-0.5 \cdot \left({\varepsilon}^{2} \cdot \cos x\right) + -1 \cdot \left(\varepsilon \cdot \sin x\right)\right)} + 0.16666666666666666 \cdot \left({\varepsilon}^{3} \cdot \sin x\right) \]
      3. associate-+l+99.8%

        \[\leadsto \color{blue}{-0.5 \cdot \left({\varepsilon}^{2} \cdot \cos x\right) + \left(-1 \cdot \left(\varepsilon \cdot \sin x\right) + 0.16666666666666666 \cdot \left({\varepsilon}^{3} \cdot \sin x\right)\right)} \]
      4. associate-*r*99.8%

        \[\leadsto \color{blue}{\left(-0.5 \cdot {\varepsilon}^{2}\right) \cdot \cos x} + \left(-1 \cdot \left(\varepsilon \cdot \sin x\right) + 0.16666666666666666 \cdot \left({\varepsilon}^{3} \cdot \sin x\right)\right) \]
      5. *-commutative99.8%

        \[\leadsto \color{blue}{\cos x \cdot \left(-0.5 \cdot {\varepsilon}^{2}\right)} + \left(-1 \cdot \left(\varepsilon \cdot \sin x\right) + 0.16666666666666666 \cdot \left({\varepsilon}^{3} \cdot \sin x\right)\right) \]
      6. associate-*r*99.8%

        \[\leadsto \cos x \cdot \left(-0.5 \cdot {\varepsilon}^{2}\right) + \left(\color{blue}{\left(-1 \cdot \varepsilon\right) \cdot \sin x} + 0.16666666666666666 \cdot \left({\varepsilon}^{3} \cdot \sin x\right)\right) \]
      7. associate-*r*99.8%

        \[\leadsto \cos x \cdot \left(-0.5 \cdot {\varepsilon}^{2}\right) + \left(\left(-1 \cdot \varepsilon\right) \cdot \sin x + \color{blue}{\left(0.16666666666666666 \cdot {\varepsilon}^{3}\right) \cdot \sin x}\right) \]
      8. distribute-rgt-out99.8%

        \[\leadsto \cos x \cdot \left(-0.5 \cdot {\varepsilon}^{2}\right) + \color{blue}{\sin x \cdot \left(-1 \cdot \varepsilon + 0.16666666666666666 \cdot {\varepsilon}^{3}\right)} \]
      9. mul-1-neg99.8%

        \[\leadsto \cos x \cdot \left(-0.5 \cdot {\varepsilon}^{2}\right) + \sin x \cdot \left(\color{blue}{\left(-\varepsilon\right)} + 0.16666666666666666 \cdot {\varepsilon}^{3}\right) \]
    4. Simplified99.8%

      \[\leadsto \color{blue}{\cos x \cdot \left(-0.5 \cdot {\varepsilon}^{2}\right) + \sin x \cdot \left(\left(-\varepsilon\right) + 0.16666666666666666 \cdot {\varepsilon}^{3}\right)} \]
    5. Taylor expanded in x around 0 99.8%

      \[\leadsto \color{blue}{-0.5 \cdot {\varepsilon}^{2} + x \cdot \left(0.16666666666666666 \cdot {\varepsilon}^{3} - \varepsilon\right)} \]

    if -8.20000000000000048e-91 < x < 1.8e-9

    1. Initial program 72.1%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in x around 0 72.1%

      \[\leadsto \color{blue}{\cos \varepsilon - 1} \]
    3. Step-by-step derivation
      1. flip--71.8%

        \[\leadsto \color{blue}{\frac{\cos \varepsilon \cdot \cos \varepsilon - 1 \cdot 1}{\cos \varepsilon + 1}} \]
      2. frac-2neg71.8%

        \[\leadsto \color{blue}{\frac{-\left(\cos \varepsilon \cdot \cos \varepsilon - 1 \cdot 1\right)}{-\left(\cos \varepsilon + 1\right)}} \]
      3. metadata-eval71.8%

        \[\leadsto \frac{-\left(\cos \varepsilon \cdot \cos \varepsilon - \color{blue}{1}\right)}{-\left(\cos \varepsilon + 1\right)} \]
      4. sub-1-cos92.6%

        \[\leadsto \frac{-\color{blue}{\left(-\sin \varepsilon \cdot \sin \varepsilon\right)}}{-\left(\cos \varepsilon + 1\right)} \]
      5. pow292.6%

        \[\leadsto \frac{-\left(-\color{blue}{{\sin \varepsilon}^{2}}\right)}{-\left(\cos \varepsilon + 1\right)} \]
    4. Applied egg-rr92.6%

      \[\leadsto \color{blue}{\frac{-\left(-{\sin \varepsilon}^{2}\right)}{-\left(\cos \varepsilon + 1\right)}} \]
    5. Step-by-step derivation
      1. remove-double-neg92.6%

        \[\leadsto \frac{\color{blue}{{\sin \varepsilon}^{2}}}{-\left(\cos \varepsilon + 1\right)} \]
      2. neg-sub092.6%

        \[\leadsto \frac{{\sin \varepsilon}^{2}}{\color{blue}{0 - \left(\cos \varepsilon + 1\right)}} \]
      3. +-commutative92.6%

        \[\leadsto \frac{{\sin \varepsilon}^{2}}{0 - \color{blue}{\left(1 + \cos \varepsilon\right)}} \]
      4. associate--r+92.6%

        \[\leadsto \frac{{\sin \varepsilon}^{2}}{\color{blue}{\left(0 - 1\right) - \cos \varepsilon}} \]
      5. metadata-eval92.6%

        \[\leadsto \frac{{\sin \varepsilon}^{2}}{\color{blue}{-1} - \cos \varepsilon} \]
    6. Simplified92.6%

      \[\leadsto \color{blue}{\frac{{\sin \varepsilon}^{2}}{-1 - \cos \varepsilon}} \]
    7. Taylor expanded in eps around inf 92.6%

      \[\leadsto \color{blue}{-1 \cdot \frac{{\sin \varepsilon}^{2}}{1 + \cos \varepsilon}} \]
    8. Step-by-step derivation
      1. mul-1-neg99.4%

        \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{-\frac{{\sin \varepsilon}^{2}}{1 + \cos \varepsilon}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      2. +-commutative99.4%

        \[\leadsto \mathsf{fma}\left(\cos x, -\frac{{\sin \varepsilon}^{2}}{\color{blue}{\cos \varepsilon + 1}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      3. unpow299.4%

        \[\leadsto \mathsf{fma}\left(\cos x, -\frac{\color{blue}{\sin \varepsilon \cdot \sin \varepsilon}}{\cos \varepsilon + 1}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      4. associate-*r/99.3%

        \[\leadsto \mathsf{fma}\left(\cos x, -\color{blue}{\sin \varepsilon \cdot \frac{\sin \varepsilon}{\cos \varepsilon + 1}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      5. distribute-rgt-neg-in99.3%

        \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{\sin \varepsilon \cdot \left(-\frac{\sin \varepsilon}{\cos \varepsilon + 1}\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      6. +-commutative99.3%

        \[\leadsto \mathsf{fma}\left(\cos x, \sin \varepsilon \cdot \left(-\frac{\sin \varepsilon}{\color{blue}{1 + \cos \varepsilon}}\right), \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      7. hang-0p-tan99.8%

        \[\leadsto \mathsf{fma}\left(\cos x, \sin \varepsilon \cdot \left(-\color{blue}{\tan \left(\frac{\varepsilon}{2}\right)}\right), \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    9. Simplified93.0%

      \[\leadsto \color{blue}{\sin \varepsilon \cdot \left(-\tan \left(\frac{\varepsilon}{2}\right)\right)} \]
  3. Recombined 4 regimes into one program.
  4. Final simplification71.0%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -7.6 \cdot 10^{-9}:\\ \;\;\;\;\sin x \cdot \left(\sin \left(\varepsilon \cdot 0.5\right) \cdot -2\right)\\ \mathbf{elif}\;x \leq -7.2 \cdot 10^{-63}:\\ \;\;\;\;-1 + \left(\cos \varepsilon - x \cdot \sin \varepsilon\right)\\ \mathbf{elif}\;x \leq -8.2 \cdot 10^{-91}:\\ \;\;\;\;-0.5 \cdot {\varepsilon}^{2} + x \cdot \left(0.16666666666666666 \cdot {\varepsilon}^{3} - \varepsilon\right)\\ \mathbf{elif}\;x \leq 1.8 \cdot 10^{-9}:\\ \;\;\;\;\tan \left(\frac{\varepsilon}{2}\right) \cdot \left(-\sin \varepsilon\right)\\ \mathbf{else}:\\ \;\;\;\;\sin x \cdot \left(\sin \left(\varepsilon \cdot 0.5\right) \cdot -2\right)\\ \end{array} \]

Alternative 8: 75.9% accurate, 0.9× speedup?

\[\begin{array}{l} \\ -2 \cdot \left(\sin \left(0.5 \cdot \left(\varepsilon + \left(x - x\right)\right)\right) \cdot \sin \left(0.5 \cdot \left(\varepsilon + \left(x + x\right)\right)\right)\right) \end{array} \]
(FPCore (x eps)
 :precision binary64
 (* -2.0 (* (sin (* 0.5 (+ eps (- x x)))) (sin (* 0.5 (+ eps (+ x x)))))))
double code(double x, double eps) {
	return -2.0 * (sin((0.5 * (eps + (x - x)))) * sin((0.5 * (eps + (x + x)))));
}
real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    code = (-2.0d0) * (sin((0.5d0 * (eps + (x - x)))) * sin((0.5d0 * (eps + (x + x)))))
end function
public static double code(double x, double eps) {
	return -2.0 * (Math.sin((0.5 * (eps + (x - x)))) * Math.sin((0.5 * (eps + (x + x)))));
}
def code(x, eps):
	return -2.0 * (math.sin((0.5 * (eps + (x - x)))) * math.sin((0.5 * (eps + (x + x)))))
function code(x, eps)
	return Float64(-2.0 * Float64(sin(Float64(0.5 * Float64(eps + Float64(x - x)))) * sin(Float64(0.5 * Float64(eps + Float64(x + x))))))
end
function tmp = code(x, eps)
	tmp = -2.0 * (sin((0.5 * (eps + (x - x)))) * sin((0.5 * (eps + (x + x)))));
end
code[x_, eps_] := N[(-2.0 * N[(N[Sin[N[(0.5 * N[(eps + N[(x - x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] * N[Sin[N[(0.5 * N[(eps + N[(x + x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
-2 \cdot \left(\sin \left(0.5 \cdot \left(\varepsilon + \left(x - x\right)\right)\right) \cdot \sin \left(0.5 \cdot \left(\varepsilon + \left(x + x\right)\right)\right)\right)
\end{array}
Derivation
  1. Initial program 37.2%

    \[\cos \left(x + \varepsilon\right) - \cos x \]
  2. Step-by-step derivation
    1. log1p-expm1-u37.1%

      \[\leadsto \color{blue}{\mathsf{log1p}\left(\mathsf{expm1}\left(\cos \left(x + \varepsilon\right) - \cos x\right)\right)} \]
  3. Applied egg-rr37.1%

    \[\leadsto \color{blue}{\mathsf{log1p}\left(\mathsf{expm1}\left(\cos \left(x + \varepsilon\right) - \cos x\right)\right)} \]
  4. Step-by-step derivation
    1. diff-cos47.1%

      \[\leadsto \mathsf{log1p}\left(\mathsf{expm1}\left(\color{blue}{-2 \cdot \left(\sin \left(\frac{\left(x + \varepsilon\right) - x}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right)}\right)\right) \]
    2. log1p-expm1-u47.2%

      \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\frac{\left(x + \varepsilon\right) - x}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right)} \]
    3. div-inv47.2%

      \[\leadsto -2 \cdot \left(\sin \color{blue}{\left(\left(\left(x + \varepsilon\right) - x\right) \cdot \frac{1}{2}\right)} \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
    4. metadata-eval47.2%

      \[\leadsto -2 \cdot \left(\sin \left(\left(\left(x + \varepsilon\right) - x\right) \cdot \color{blue}{0.5}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
    5. div-inv47.2%

      \[\leadsto -2 \cdot \left(\sin \left(\left(\left(x + \varepsilon\right) - x\right) \cdot 0.5\right) \cdot \sin \color{blue}{\left(\left(\left(x + \varepsilon\right) + x\right) \cdot \frac{1}{2}\right)}\right) \]
    6. metadata-eval47.2%

      \[\leadsto -2 \cdot \left(\sin \left(\left(\left(x + \varepsilon\right) - x\right) \cdot 0.5\right) \cdot \sin \left(\left(\left(x + \varepsilon\right) + x\right) \cdot \color{blue}{0.5}\right)\right) \]
  5. Applied egg-rr47.2%

    \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\left(\left(x + \varepsilon\right) - x\right) \cdot 0.5\right) \cdot \sin \left(\left(\left(x + \varepsilon\right) + x\right) \cdot 0.5\right)\right)} \]
  6. Step-by-step derivation
    1. *-commutative47.2%

      \[\leadsto -2 \cdot \left(\sin \color{blue}{\left(0.5 \cdot \left(\left(x + \varepsilon\right) - x\right)\right)} \cdot \sin \left(\left(\left(x + \varepsilon\right) + x\right) \cdot 0.5\right)\right) \]
    2. +-commutative47.2%

      \[\leadsto -2 \cdot \left(\sin \left(0.5 \cdot \left(\color{blue}{\left(\varepsilon + x\right)} - x\right)\right) \cdot \sin \left(\left(\left(x + \varepsilon\right) + x\right) \cdot 0.5\right)\right) \]
    3. associate--l+73.9%

      \[\leadsto -2 \cdot \left(\sin \left(0.5 \cdot \color{blue}{\left(\varepsilon + \left(x - x\right)\right)}\right) \cdot \sin \left(\left(\left(x + \varepsilon\right) + x\right) \cdot 0.5\right)\right) \]
    4. *-commutative73.9%

      \[\leadsto -2 \cdot \left(\sin \left(0.5 \cdot \left(\varepsilon + \left(x - x\right)\right)\right) \cdot \sin \color{blue}{\left(0.5 \cdot \left(\left(x + \varepsilon\right) + x\right)\right)}\right) \]
    5. +-commutative73.9%

      \[\leadsto -2 \cdot \left(\sin \left(0.5 \cdot \left(\varepsilon + \left(x - x\right)\right)\right) \cdot \sin \left(0.5 \cdot \left(\color{blue}{\left(\varepsilon + x\right)} + x\right)\right)\right) \]
    6. associate-+l+74.0%

      \[\leadsto -2 \cdot \left(\sin \left(0.5 \cdot \left(\varepsilon + \left(x - x\right)\right)\right) \cdot \sin \left(0.5 \cdot \color{blue}{\left(\varepsilon + \left(x + x\right)\right)}\right)\right) \]
  7. Simplified74.0%

    \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(0.5 \cdot \left(\varepsilon + \left(x - x\right)\right)\right) \cdot \sin \left(0.5 \cdot \left(\varepsilon + \left(x + x\right)\right)\right)\right)} \]
  8. Final simplification74.0%

    \[\leadsto -2 \cdot \left(\sin \left(0.5 \cdot \left(\varepsilon + \left(x - x\right)\right)\right) \cdot \sin \left(0.5 \cdot \left(\varepsilon + \left(x + x\right)\right)\right)\right) \]

Alternative 9: 70.1% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq -2.8 \cdot 10^{-9} \lor \neg \left(x \leq 1.3 \cdot 10^{-9}\right):\\ \;\;\;\;\sin x \cdot \left(\sin \left(\varepsilon \cdot 0.5\right) \cdot -2\right)\\ \mathbf{else}:\\ \;\;\;\;\tan \left(\frac{\varepsilon}{2}\right) \cdot \left(-\sin \varepsilon\right)\\ \end{array} \end{array} \]
(FPCore (x eps)
 :precision binary64
 (if (or (<= x -2.8e-9) (not (<= x 1.3e-9)))
   (* (sin x) (* (sin (* eps 0.5)) -2.0))
   (* (tan (/ eps 2.0)) (- (sin eps)))))
double code(double x, double eps) {
	double tmp;
	if ((x <= -2.8e-9) || !(x <= 1.3e-9)) {
		tmp = sin(x) * (sin((eps * 0.5)) * -2.0);
	} else {
		tmp = tan((eps / 2.0)) * -sin(eps);
	}
	return tmp;
}
real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    real(8) :: tmp
    if ((x <= (-2.8d-9)) .or. (.not. (x <= 1.3d-9))) then
        tmp = sin(x) * (sin((eps * 0.5d0)) * (-2.0d0))
    else
        tmp = tan((eps / 2.0d0)) * -sin(eps)
    end if
    code = tmp
end function
public static double code(double x, double eps) {
	double tmp;
	if ((x <= -2.8e-9) || !(x <= 1.3e-9)) {
		tmp = Math.sin(x) * (Math.sin((eps * 0.5)) * -2.0);
	} else {
		tmp = Math.tan((eps / 2.0)) * -Math.sin(eps);
	}
	return tmp;
}
def code(x, eps):
	tmp = 0
	if (x <= -2.8e-9) or not (x <= 1.3e-9):
		tmp = math.sin(x) * (math.sin((eps * 0.5)) * -2.0)
	else:
		tmp = math.tan((eps / 2.0)) * -math.sin(eps)
	return tmp
function code(x, eps)
	tmp = 0.0
	if ((x <= -2.8e-9) || !(x <= 1.3e-9))
		tmp = Float64(sin(x) * Float64(sin(Float64(eps * 0.5)) * -2.0));
	else
		tmp = Float64(tan(Float64(eps / 2.0)) * Float64(-sin(eps)));
	end
	return tmp
end
function tmp_2 = code(x, eps)
	tmp = 0.0;
	if ((x <= -2.8e-9) || ~((x <= 1.3e-9)))
		tmp = sin(x) * (sin((eps * 0.5)) * -2.0);
	else
		tmp = tan((eps / 2.0)) * -sin(eps);
	end
	tmp_2 = tmp;
end
code[x_, eps_] := If[Or[LessEqual[x, -2.8e-9], N[Not[LessEqual[x, 1.3e-9]], $MachinePrecision]], N[(N[Sin[x], $MachinePrecision] * N[(N[Sin[N[(eps * 0.5), $MachinePrecision]], $MachinePrecision] * -2.0), $MachinePrecision]), $MachinePrecision], N[(N[Tan[N[(eps / 2.0), $MachinePrecision]], $MachinePrecision] * (-N[Sin[eps], $MachinePrecision])), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq -2.8 \cdot 10^{-9} \lor \neg \left(x \leq 1.3 \cdot 10^{-9}\right):\\
\;\;\;\;\sin x \cdot \left(\sin \left(\varepsilon \cdot 0.5\right) \cdot -2\right)\\

\mathbf{else}:\\
\;\;\;\;\tan \left(\frac{\varepsilon}{2}\right) \cdot \left(-\sin \varepsilon\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < -2.79999999999999984e-9 or 1.3000000000000001e-9 < x

    1. Initial program 6.6%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Step-by-step derivation
      1. diff-cos7.3%

        \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\frac{\left(x + \varepsilon\right) - x}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right)} \]
      2. div-inv7.3%

        \[\leadsto -2 \cdot \left(\sin \color{blue}{\left(\left(\left(x + \varepsilon\right) - x\right) \cdot \frac{1}{2}\right)} \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      3. associate--l+7.3%

        \[\leadsto -2 \cdot \left(\sin \left(\color{blue}{\left(x + \left(\varepsilon - x\right)\right)} \cdot \frac{1}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      4. metadata-eval7.3%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot \color{blue}{0.5}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      5. div-inv7.3%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \color{blue}{\left(\left(\left(x + \varepsilon\right) + x\right) \cdot \frac{1}{2}\right)}\right) \]
      6. +-commutative7.3%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\color{blue}{\left(\varepsilon + x\right)} + x\right) \cdot \frac{1}{2}\right)\right) \]
      7. associate-+l+7.6%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\color{blue}{\left(\varepsilon + \left(x + x\right)\right)} \cdot \frac{1}{2}\right)\right) \]
      8. metadata-eval7.6%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot \color{blue}{0.5}\right)\right) \]
    3. Applied egg-rr7.6%

      \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)\right)} \]
    4. Step-by-step derivation
      1. associate-*r*7.6%

        \[\leadsto \color{blue}{\left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)} \]
      2. *-commutative7.6%

        \[\leadsto \color{blue}{\sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right)} \]
      3. *-commutative7.6%

        \[\leadsto \sin \color{blue}{\left(0.5 \cdot \left(\varepsilon + \left(x + x\right)\right)\right)} \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      4. +-commutative7.6%

        \[\leadsto \sin \left(0.5 \cdot \color{blue}{\left(\left(x + x\right) + \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      5. count-27.6%

        \[\leadsto \sin \left(0.5 \cdot \left(\color{blue}{2 \cdot x} + \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      6. fma-def7.6%

        \[\leadsto \sin \left(0.5 \cdot \color{blue}{\mathsf{fma}\left(2, x, \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      7. sub-neg7.6%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(\varepsilon + \left(-x\right)\right)}\right) \cdot 0.5\right)\right) \]
      8. mul-1-neg7.6%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon + \color{blue}{-1 \cdot x}\right)\right) \cdot 0.5\right)\right) \]
      9. +-commutative7.6%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(-1 \cdot x + \varepsilon\right)}\right) \cdot 0.5\right)\right) \]
      10. associate-+r+51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(\left(x + -1 \cdot x\right) + \varepsilon\right)} \cdot 0.5\right)\right) \]
      11. mul-1-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\left(x + \color{blue}{\left(-x\right)}\right) + \varepsilon\right) \cdot 0.5\right)\right) \]
      12. sub-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{\left(x - x\right)} + \varepsilon\right) \cdot 0.5\right)\right) \]
      13. +-inverses51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{0} + \varepsilon\right) \cdot 0.5\right)\right) \]
      14. remove-double-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \color{blue}{\left(-\left(-\varepsilon\right)\right)}\right) \cdot 0.5\right)\right) \]
      15. mul-1-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \left(-\color{blue}{-1 \cdot \varepsilon}\right)\right) \cdot 0.5\right)\right) \]
      16. sub-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(0 - -1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
      17. neg-sub051.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(--1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
      18. mul-1-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(-\color{blue}{\left(-\varepsilon\right)}\right) \cdot 0.5\right)\right) \]
      19. remove-double-neg51.0%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\varepsilon} \cdot 0.5\right)\right) \]
    5. Simplified51.0%

      \[\leadsto \color{blue}{\sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\varepsilon \cdot 0.5\right)\right)} \]
    6. Taylor expanded in eps around 0 50.8%

      \[\leadsto \color{blue}{\sin x} \cdot \left(-2 \cdot \sin \left(\varepsilon \cdot 0.5\right)\right) \]

    if -2.79999999999999984e-9 < x < 1.3000000000000001e-9

    1. Initial program 70.4%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in x around 0 70.4%

      \[\leadsto \color{blue}{\cos \varepsilon - 1} \]
    3. Step-by-step derivation
      1. flip--70.1%

        \[\leadsto \color{blue}{\frac{\cos \varepsilon \cdot \cos \varepsilon - 1 \cdot 1}{\cos \varepsilon + 1}} \]
      2. frac-2neg70.1%

        \[\leadsto \color{blue}{\frac{-\left(\cos \varepsilon \cdot \cos \varepsilon - 1 \cdot 1\right)}{-\left(\cos \varepsilon + 1\right)}} \]
      3. metadata-eval70.1%

        \[\leadsto \frac{-\left(\cos \varepsilon \cdot \cos \varepsilon - \color{blue}{1}\right)}{-\left(\cos \varepsilon + 1\right)} \]
      4. sub-1-cos88.7%

        \[\leadsto \frac{-\color{blue}{\left(-\sin \varepsilon \cdot \sin \varepsilon\right)}}{-\left(\cos \varepsilon + 1\right)} \]
      5. pow288.7%

        \[\leadsto \frac{-\left(-\color{blue}{{\sin \varepsilon}^{2}}\right)}{-\left(\cos \varepsilon + 1\right)} \]
    4. Applied egg-rr88.7%

      \[\leadsto \color{blue}{\frac{-\left(-{\sin \varepsilon}^{2}\right)}{-\left(\cos \varepsilon + 1\right)}} \]
    5. Step-by-step derivation
      1. remove-double-neg88.7%

        \[\leadsto \frac{\color{blue}{{\sin \varepsilon}^{2}}}{-\left(\cos \varepsilon + 1\right)} \]
      2. neg-sub088.7%

        \[\leadsto \frac{{\sin \varepsilon}^{2}}{\color{blue}{0 - \left(\cos \varepsilon + 1\right)}} \]
      3. +-commutative88.7%

        \[\leadsto \frac{{\sin \varepsilon}^{2}}{0 - \color{blue}{\left(1 + \cos \varepsilon\right)}} \]
      4. associate--r+88.7%

        \[\leadsto \frac{{\sin \varepsilon}^{2}}{\color{blue}{\left(0 - 1\right) - \cos \varepsilon}} \]
      5. metadata-eval88.7%

        \[\leadsto \frac{{\sin \varepsilon}^{2}}{\color{blue}{-1} - \cos \varepsilon} \]
    6. Simplified88.7%

      \[\leadsto \color{blue}{\frac{{\sin \varepsilon}^{2}}{-1 - \cos \varepsilon}} \]
    7. Taylor expanded in eps around inf 88.7%

      \[\leadsto \color{blue}{-1 \cdot \frac{{\sin \varepsilon}^{2}}{1 + \cos \varepsilon}} \]
    8. Step-by-step derivation
      1. mul-1-neg99.3%

        \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{-\frac{{\sin \varepsilon}^{2}}{1 + \cos \varepsilon}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      2. +-commutative99.3%

        \[\leadsto \mathsf{fma}\left(\cos x, -\frac{{\sin \varepsilon}^{2}}{\color{blue}{\cos \varepsilon + 1}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      3. unpow299.3%

        \[\leadsto \mathsf{fma}\left(\cos x, -\frac{\color{blue}{\sin \varepsilon \cdot \sin \varepsilon}}{\cos \varepsilon + 1}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      4. associate-*r/99.3%

        \[\leadsto \mathsf{fma}\left(\cos x, -\color{blue}{\sin \varepsilon \cdot \frac{\sin \varepsilon}{\cos \varepsilon + 1}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      5. distribute-rgt-neg-in99.3%

        \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{\sin \varepsilon \cdot \left(-\frac{\sin \varepsilon}{\cos \varepsilon + 1}\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      6. +-commutative99.3%

        \[\leadsto \mathsf{fma}\left(\cos x, \sin \varepsilon \cdot \left(-\frac{\sin \varepsilon}{\color{blue}{1 + \cos \varepsilon}}\right), \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      7. hang-0p-tan99.8%

        \[\leadsto \mathsf{fma}\left(\cos x, \sin \varepsilon \cdot \left(-\color{blue}{\tan \left(\frac{\varepsilon}{2}\right)}\right), \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    9. Simplified89.2%

      \[\leadsto \color{blue}{\sin \varepsilon \cdot \left(-\tan \left(\frac{\varepsilon}{2}\right)\right)} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification69.3%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -2.8 \cdot 10^{-9} \lor \neg \left(x \leq 1.3 \cdot 10^{-9}\right):\\ \;\;\;\;\sin x \cdot \left(\sin \left(\varepsilon \cdot 0.5\right) \cdot -2\right)\\ \mathbf{else}:\\ \;\;\;\;\tan \left(\frac{\varepsilon}{2}\right) \cdot \left(-\sin \varepsilon\right)\\ \end{array} \]

Alternative 10: 68.2% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq -2.75 \cdot 10^{-9} \lor \neg \left(x \leq 3.9 \cdot 10^{-12}\right):\\ \;\;\;\;\varepsilon \cdot \left(-\sin x\right)\\ \mathbf{else}:\\ \;\;\;\;-2 \cdot {\sin \left(\varepsilon \cdot 0.5\right)}^{2}\\ \end{array} \end{array} \]
(FPCore (x eps)
 :precision binary64
 (if (or (<= x -2.75e-9) (not (<= x 3.9e-12)))
   (* eps (- (sin x)))
   (* -2.0 (pow (sin (* eps 0.5)) 2.0))))
double code(double x, double eps) {
	double tmp;
	if ((x <= -2.75e-9) || !(x <= 3.9e-12)) {
		tmp = eps * -sin(x);
	} else {
		tmp = -2.0 * pow(sin((eps * 0.5)), 2.0);
	}
	return tmp;
}
real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    real(8) :: tmp
    if ((x <= (-2.75d-9)) .or. (.not. (x <= 3.9d-12))) then
        tmp = eps * -sin(x)
    else
        tmp = (-2.0d0) * (sin((eps * 0.5d0)) ** 2.0d0)
    end if
    code = tmp
end function
public static double code(double x, double eps) {
	double tmp;
	if ((x <= -2.75e-9) || !(x <= 3.9e-12)) {
		tmp = eps * -Math.sin(x);
	} else {
		tmp = -2.0 * Math.pow(Math.sin((eps * 0.5)), 2.0);
	}
	return tmp;
}
def code(x, eps):
	tmp = 0
	if (x <= -2.75e-9) or not (x <= 3.9e-12):
		tmp = eps * -math.sin(x)
	else:
		tmp = -2.0 * math.pow(math.sin((eps * 0.5)), 2.0)
	return tmp
function code(x, eps)
	tmp = 0.0
	if ((x <= -2.75e-9) || !(x <= 3.9e-12))
		tmp = Float64(eps * Float64(-sin(x)));
	else
		tmp = Float64(-2.0 * (sin(Float64(eps * 0.5)) ^ 2.0));
	end
	return tmp
end
function tmp_2 = code(x, eps)
	tmp = 0.0;
	if ((x <= -2.75e-9) || ~((x <= 3.9e-12)))
		tmp = eps * -sin(x);
	else
		tmp = -2.0 * (sin((eps * 0.5)) ^ 2.0);
	end
	tmp_2 = tmp;
end
code[x_, eps_] := If[Or[LessEqual[x, -2.75e-9], N[Not[LessEqual[x, 3.9e-12]], $MachinePrecision]], N[(eps * (-N[Sin[x], $MachinePrecision])), $MachinePrecision], N[(-2.0 * N[Power[N[Sin[N[(eps * 0.5), $MachinePrecision]], $MachinePrecision], 2.0], $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq -2.75 \cdot 10^{-9} \lor \neg \left(x \leq 3.9 \cdot 10^{-12}\right):\\
\;\;\;\;\varepsilon \cdot \left(-\sin x\right)\\

\mathbf{else}:\\
\;\;\;\;-2 \cdot {\sin \left(\varepsilon \cdot 0.5\right)}^{2}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < -2.7499999999999998e-9 or 3.89999999999999994e-12 < x

    1. Initial program 6.6%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in eps around 0 45.9%

      \[\leadsto \color{blue}{-1 \cdot \left(\varepsilon \cdot \sin x\right)} \]
    3. Step-by-step derivation
      1. mul-1-neg45.9%

        \[\leadsto \color{blue}{-\varepsilon \cdot \sin x} \]
      2. *-commutative45.9%

        \[\leadsto -\color{blue}{\sin x \cdot \varepsilon} \]
      3. distribute-rgt-neg-in45.9%

        \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]
    4. Simplified45.9%

      \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]

    if -2.7499999999999998e-9 < x < 3.89999999999999994e-12

    1. Initial program 70.4%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Step-by-step derivation
      1. diff-cos90.4%

        \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\frac{\left(x + \varepsilon\right) - x}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right)} \]
      2. div-inv90.4%

        \[\leadsto -2 \cdot \left(\sin \color{blue}{\left(\left(\left(x + \varepsilon\right) - x\right) \cdot \frac{1}{2}\right)} \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      3. associate--l+90.4%

        \[\leadsto -2 \cdot \left(\sin \left(\color{blue}{\left(x + \left(\varepsilon - x\right)\right)} \cdot \frac{1}{2}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      4. metadata-eval90.4%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot \color{blue}{0.5}\right) \cdot \sin \left(\frac{\left(x + \varepsilon\right) + x}{2}\right)\right) \]
      5. div-inv90.4%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \color{blue}{\left(\left(\left(x + \varepsilon\right) + x\right) \cdot \frac{1}{2}\right)}\right) \]
      6. +-commutative90.4%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\color{blue}{\left(\varepsilon + x\right)} + x\right) \cdot \frac{1}{2}\right)\right) \]
      7. associate-+l+90.4%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\color{blue}{\left(\varepsilon + \left(x + x\right)\right)} \cdot \frac{1}{2}\right)\right) \]
      8. metadata-eval90.4%

        \[\leadsto -2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot \color{blue}{0.5}\right)\right) \]
    3. Applied egg-rr90.4%

      \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)\right)} \]
    4. Step-by-step derivation
      1. associate-*r*90.4%

        \[\leadsto \color{blue}{\left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \cdot \sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right)} \]
      2. *-commutative90.4%

        \[\leadsto \color{blue}{\sin \left(\left(\varepsilon + \left(x + x\right)\right) \cdot 0.5\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right)} \]
      3. *-commutative90.4%

        \[\leadsto \sin \color{blue}{\left(0.5 \cdot \left(\varepsilon + \left(x + x\right)\right)\right)} \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      4. +-commutative90.4%

        \[\leadsto \sin \left(0.5 \cdot \color{blue}{\left(\left(x + x\right) + \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      5. count-290.4%

        \[\leadsto \sin \left(0.5 \cdot \left(\color{blue}{2 \cdot x} + \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      6. fma-def90.4%

        \[\leadsto \sin \left(0.5 \cdot \color{blue}{\mathsf{fma}\left(2, x, \varepsilon\right)}\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon - x\right)\right) \cdot 0.5\right)\right) \]
      7. sub-neg90.4%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(\varepsilon + \left(-x\right)\right)}\right) \cdot 0.5\right)\right) \]
      8. mul-1-neg90.4%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \left(\varepsilon + \color{blue}{-1 \cdot x}\right)\right) \cdot 0.5\right)\right) \]
      9. +-commutative90.4%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(x + \color{blue}{\left(-1 \cdot x + \varepsilon\right)}\right) \cdot 0.5\right)\right) \]
      10. associate-+r+98.8%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(\left(x + -1 \cdot x\right) + \varepsilon\right)} \cdot 0.5\right)\right) \]
      11. mul-1-neg98.8%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\left(x + \color{blue}{\left(-x\right)}\right) + \varepsilon\right) \cdot 0.5\right)\right) \]
      12. sub-neg98.8%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{\left(x - x\right)} + \varepsilon\right) \cdot 0.5\right)\right) \]
      13. +-inverses98.8%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(\color{blue}{0} + \varepsilon\right) \cdot 0.5\right)\right) \]
      14. remove-double-neg98.8%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \color{blue}{\left(-\left(-\varepsilon\right)\right)}\right) \cdot 0.5\right)\right) \]
      15. mul-1-neg98.8%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(0 + \left(-\color{blue}{-1 \cdot \varepsilon}\right)\right) \cdot 0.5\right)\right) \]
      16. sub-neg98.8%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(0 - -1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
      17. neg-sub098.8%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\left(--1 \cdot \varepsilon\right)} \cdot 0.5\right)\right) \]
      18. mul-1-neg98.8%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\left(-\color{blue}{\left(-\varepsilon\right)}\right) \cdot 0.5\right)\right) \]
      19. remove-double-neg98.8%

        \[\leadsto \sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\color{blue}{\varepsilon} \cdot 0.5\right)\right) \]
    5. Simplified98.8%

      \[\leadsto \color{blue}{\sin \left(0.5 \cdot \mathsf{fma}\left(2, x, \varepsilon\right)\right) \cdot \left(-2 \cdot \sin \left(\varepsilon \cdot 0.5\right)\right)} \]
    6. Taylor expanded in x around 0 89.0%

      \[\leadsto \color{blue}{-2 \cdot {\sin \left(0.5 \cdot \varepsilon\right)}^{2}} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification66.6%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -2.75 \cdot 10^{-9} \lor \neg \left(x \leq 3.9 \cdot 10^{-12}\right):\\ \;\;\;\;\varepsilon \cdot \left(-\sin x\right)\\ \mathbf{else}:\\ \;\;\;\;-2 \cdot {\sin \left(\varepsilon \cdot 0.5\right)}^{2}\\ \end{array} \]

Alternative 11: 68.3% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq -2.7 \cdot 10^{-9} \lor \neg \left(x \leq 1.9 \cdot 10^{-12}\right):\\ \;\;\;\;\varepsilon \cdot \left(-\sin x\right)\\ \mathbf{else}:\\ \;\;\;\;\tan \left(\frac{\varepsilon}{2}\right) \cdot \left(-\sin \varepsilon\right)\\ \end{array} \end{array} \]
(FPCore (x eps)
 :precision binary64
 (if (or (<= x -2.7e-9) (not (<= x 1.9e-12)))
   (* eps (- (sin x)))
   (* (tan (/ eps 2.0)) (- (sin eps)))))
double code(double x, double eps) {
	double tmp;
	if ((x <= -2.7e-9) || !(x <= 1.9e-12)) {
		tmp = eps * -sin(x);
	} else {
		tmp = tan((eps / 2.0)) * -sin(eps);
	}
	return tmp;
}
real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    real(8) :: tmp
    if ((x <= (-2.7d-9)) .or. (.not. (x <= 1.9d-12))) then
        tmp = eps * -sin(x)
    else
        tmp = tan((eps / 2.0d0)) * -sin(eps)
    end if
    code = tmp
end function
public static double code(double x, double eps) {
	double tmp;
	if ((x <= -2.7e-9) || !(x <= 1.9e-12)) {
		tmp = eps * -Math.sin(x);
	} else {
		tmp = Math.tan((eps / 2.0)) * -Math.sin(eps);
	}
	return tmp;
}
def code(x, eps):
	tmp = 0
	if (x <= -2.7e-9) or not (x <= 1.9e-12):
		tmp = eps * -math.sin(x)
	else:
		tmp = math.tan((eps / 2.0)) * -math.sin(eps)
	return tmp
function code(x, eps)
	tmp = 0.0
	if ((x <= -2.7e-9) || !(x <= 1.9e-12))
		tmp = Float64(eps * Float64(-sin(x)));
	else
		tmp = Float64(tan(Float64(eps / 2.0)) * Float64(-sin(eps)));
	end
	return tmp
end
function tmp_2 = code(x, eps)
	tmp = 0.0;
	if ((x <= -2.7e-9) || ~((x <= 1.9e-12)))
		tmp = eps * -sin(x);
	else
		tmp = tan((eps / 2.0)) * -sin(eps);
	end
	tmp_2 = tmp;
end
code[x_, eps_] := If[Or[LessEqual[x, -2.7e-9], N[Not[LessEqual[x, 1.9e-12]], $MachinePrecision]], N[(eps * (-N[Sin[x], $MachinePrecision])), $MachinePrecision], N[(N[Tan[N[(eps / 2.0), $MachinePrecision]], $MachinePrecision] * (-N[Sin[eps], $MachinePrecision])), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq -2.7 \cdot 10^{-9} \lor \neg \left(x \leq 1.9 \cdot 10^{-12}\right):\\
\;\;\;\;\varepsilon \cdot \left(-\sin x\right)\\

\mathbf{else}:\\
\;\;\;\;\tan \left(\frac{\varepsilon}{2}\right) \cdot \left(-\sin \varepsilon\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < -2.7000000000000002e-9 or 1.89999999999999998e-12 < x

    1. Initial program 6.6%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in eps around 0 45.9%

      \[\leadsto \color{blue}{-1 \cdot \left(\varepsilon \cdot \sin x\right)} \]
    3. Step-by-step derivation
      1. mul-1-neg45.9%

        \[\leadsto \color{blue}{-\varepsilon \cdot \sin x} \]
      2. *-commutative45.9%

        \[\leadsto -\color{blue}{\sin x \cdot \varepsilon} \]
      3. distribute-rgt-neg-in45.9%

        \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]
    4. Simplified45.9%

      \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]

    if -2.7000000000000002e-9 < x < 1.89999999999999998e-12

    1. Initial program 70.4%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in x around 0 70.4%

      \[\leadsto \color{blue}{\cos \varepsilon - 1} \]
    3. Step-by-step derivation
      1. flip--70.1%

        \[\leadsto \color{blue}{\frac{\cos \varepsilon \cdot \cos \varepsilon - 1 \cdot 1}{\cos \varepsilon + 1}} \]
      2. frac-2neg70.1%

        \[\leadsto \color{blue}{\frac{-\left(\cos \varepsilon \cdot \cos \varepsilon - 1 \cdot 1\right)}{-\left(\cos \varepsilon + 1\right)}} \]
      3. metadata-eval70.1%

        \[\leadsto \frac{-\left(\cos \varepsilon \cdot \cos \varepsilon - \color{blue}{1}\right)}{-\left(\cos \varepsilon + 1\right)} \]
      4. sub-1-cos88.7%

        \[\leadsto \frac{-\color{blue}{\left(-\sin \varepsilon \cdot \sin \varepsilon\right)}}{-\left(\cos \varepsilon + 1\right)} \]
      5. pow288.7%

        \[\leadsto \frac{-\left(-\color{blue}{{\sin \varepsilon}^{2}}\right)}{-\left(\cos \varepsilon + 1\right)} \]
    4. Applied egg-rr88.7%

      \[\leadsto \color{blue}{\frac{-\left(-{\sin \varepsilon}^{2}\right)}{-\left(\cos \varepsilon + 1\right)}} \]
    5. Step-by-step derivation
      1. remove-double-neg88.7%

        \[\leadsto \frac{\color{blue}{{\sin \varepsilon}^{2}}}{-\left(\cos \varepsilon + 1\right)} \]
      2. neg-sub088.7%

        \[\leadsto \frac{{\sin \varepsilon}^{2}}{\color{blue}{0 - \left(\cos \varepsilon + 1\right)}} \]
      3. +-commutative88.7%

        \[\leadsto \frac{{\sin \varepsilon}^{2}}{0 - \color{blue}{\left(1 + \cos \varepsilon\right)}} \]
      4. associate--r+88.7%

        \[\leadsto \frac{{\sin \varepsilon}^{2}}{\color{blue}{\left(0 - 1\right) - \cos \varepsilon}} \]
      5. metadata-eval88.7%

        \[\leadsto \frac{{\sin \varepsilon}^{2}}{\color{blue}{-1} - \cos \varepsilon} \]
    6. Simplified88.7%

      \[\leadsto \color{blue}{\frac{{\sin \varepsilon}^{2}}{-1 - \cos \varepsilon}} \]
    7. Taylor expanded in eps around inf 88.7%

      \[\leadsto \color{blue}{-1 \cdot \frac{{\sin \varepsilon}^{2}}{1 + \cos \varepsilon}} \]
    8. Step-by-step derivation
      1. mul-1-neg99.3%

        \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{-\frac{{\sin \varepsilon}^{2}}{1 + \cos \varepsilon}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      2. +-commutative99.3%

        \[\leadsto \mathsf{fma}\left(\cos x, -\frac{{\sin \varepsilon}^{2}}{\color{blue}{\cos \varepsilon + 1}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      3. unpow299.3%

        \[\leadsto \mathsf{fma}\left(\cos x, -\frac{\color{blue}{\sin \varepsilon \cdot \sin \varepsilon}}{\cos \varepsilon + 1}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      4. associate-*r/99.3%

        \[\leadsto \mathsf{fma}\left(\cos x, -\color{blue}{\sin \varepsilon \cdot \frac{\sin \varepsilon}{\cos \varepsilon + 1}}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      5. distribute-rgt-neg-in99.3%

        \[\leadsto \mathsf{fma}\left(\cos x, \color{blue}{\sin \varepsilon \cdot \left(-\frac{\sin \varepsilon}{\cos \varepsilon + 1}\right)}, \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      6. +-commutative99.3%

        \[\leadsto \mathsf{fma}\left(\cos x, \sin \varepsilon \cdot \left(-\frac{\sin \varepsilon}{\color{blue}{1 + \cos \varepsilon}}\right), \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
      7. hang-0p-tan99.8%

        \[\leadsto \mathsf{fma}\left(\cos x, \sin \varepsilon \cdot \left(-\color{blue}{\tan \left(\frac{\varepsilon}{2}\right)}\right), \sin x \cdot \left(-\sin \varepsilon\right)\right) \]
    9. Simplified89.2%

      \[\leadsto \color{blue}{\sin \varepsilon \cdot \left(-\tan \left(\frac{\varepsilon}{2}\right)\right)} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification66.7%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -2.7 \cdot 10^{-9} \lor \neg \left(x \leq 1.9 \cdot 10^{-12}\right):\\ \;\;\;\;\varepsilon \cdot \left(-\sin x\right)\\ \mathbf{else}:\\ \;\;\;\;\tan \left(\frac{\varepsilon}{2}\right) \cdot \left(-\sin \varepsilon\right)\\ \end{array} \]

Alternative 12: 49.5% accurate, 1.8× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \cos \varepsilon + -1\\ t_1 := -0.5 \cdot {\varepsilon}^{2}\\ \mathbf{if}\;\varepsilon \leq -0.000156:\\ \;\;\;\;t_0\\ \mathbf{elif}\;\varepsilon \leq -2.45 \cdot 10^{-147}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;\varepsilon \leq 3.2 \cdot 10^{-144}:\\ \;\;\;\;\varepsilon \cdot \left(-x\right)\\ \mathbf{elif}\;\varepsilon \leq 0.00016:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;t_0\\ \end{array} \end{array} \]
(FPCore (x eps)
 :precision binary64
 (let* ((t_0 (+ (cos eps) -1.0)) (t_1 (* -0.5 (pow eps 2.0))))
   (if (<= eps -0.000156)
     t_0
     (if (<= eps -2.45e-147)
       t_1
       (if (<= eps 3.2e-144) (* eps (- x)) (if (<= eps 0.00016) t_1 t_0))))))
double code(double x, double eps) {
	double t_0 = cos(eps) + -1.0;
	double t_1 = -0.5 * pow(eps, 2.0);
	double tmp;
	if (eps <= -0.000156) {
		tmp = t_0;
	} else if (eps <= -2.45e-147) {
		tmp = t_1;
	} else if (eps <= 3.2e-144) {
		tmp = eps * -x;
	} else if (eps <= 0.00016) {
		tmp = t_1;
	} else {
		tmp = t_0;
	}
	return tmp;
}
real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    real(8) :: t_0
    real(8) :: t_1
    real(8) :: tmp
    t_0 = cos(eps) + (-1.0d0)
    t_1 = (-0.5d0) * (eps ** 2.0d0)
    if (eps <= (-0.000156d0)) then
        tmp = t_0
    else if (eps <= (-2.45d-147)) then
        tmp = t_1
    else if (eps <= 3.2d-144) then
        tmp = eps * -x
    else if (eps <= 0.00016d0) then
        tmp = t_1
    else
        tmp = t_0
    end if
    code = tmp
end function
public static double code(double x, double eps) {
	double t_0 = Math.cos(eps) + -1.0;
	double t_1 = -0.5 * Math.pow(eps, 2.0);
	double tmp;
	if (eps <= -0.000156) {
		tmp = t_0;
	} else if (eps <= -2.45e-147) {
		tmp = t_1;
	} else if (eps <= 3.2e-144) {
		tmp = eps * -x;
	} else if (eps <= 0.00016) {
		tmp = t_1;
	} else {
		tmp = t_0;
	}
	return tmp;
}
def code(x, eps):
	t_0 = math.cos(eps) + -1.0
	t_1 = -0.5 * math.pow(eps, 2.0)
	tmp = 0
	if eps <= -0.000156:
		tmp = t_0
	elif eps <= -2.45e-147:
		tmp = t_1
	elif eps <= 3.2e-144:
		tmp = eps * -x
	elif eps <= 0.00016:
		tmp = t_1
	else:
		tmp = t_0
	return tmp
function code(x, eps)
	t_0 = Float64(cos(eps) + -1.0)
	t_1 = Float64(-0.5 * (eps ^ 2.0))
	tmp = 0.0
	if (eps <= -0.000156)
		tmp = t_0;
	elseif (eps <= -2.45e-147)
		tmp = t_1;
	elseif (eps <= 3.2e-144)
		tmp = Float64(eps * Float64(-x));
	elseif (eps <= 0.00016)
		tmp = t_1;
	else
		tmp = t_0;
	end
	return tmp
end
function tmp_2 = code(x, eps)
	t_0 = cos(eps) + -1.0;
	t_1 = -0.5 * (eps ^ 2.0);
	tmp = 0.0;
	if (eps <= -0.000156)
		tmp = t_0;
	elseif (eps <= -2.45e-147)
		tmp = t_1;
	elseif (eps <= 3.2e-144)
		tmp = eps * -x;
	elseif (eps <= 0.00016)
		tmp = t_1;
	else
		tmp = t_0;
	end
	tmp_2 = tmp;
end
code[x_, eps_] := Block[{t$95$0 = N[(N[Cos[eps], $MachinePrecision] + -1.0), $MachinePrecision]}, Block[{t$95$1 = N[(-0.5 * N[Power[eps, 2.0], $MachinePrecision]), $MachinePrecision]}, If[LessEqual[eps, -0.000156], t$95$0, If[LessEqual[eps, -2.45e-147], t$95$1, If[LessEqual[eps, 3.2e-144], N[(eps * (-x)), $MachinePrecision], If[LessEqual[eps, 0.00016], t$95$1, t$95$0]]]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \cos \varepsilon + -1\\
t_1 := -0.5 \cdot {\varepsilon}^{2}\\
\mathbf{if}\;\varepsilon \leq -0.000156:\\
\;\;\;\;t_0\\

\mathbf{elif}\;\varepsilon \leq -2.45 \cdot 10^{-147}:\\
\;\;\;\;t_1\\

\mathbf{elif}\;\varepsilon \leq 3.2 \cdot 10^{-144}:\\
\;\;\;\;\varepsilon \cdot \left(-x\right)\\

\mathbf{elif}\;\varepsilon \leq 0.00016:\\
\;\;\;\;t_1\\

\mathbf{else}:\\
\;\;\;\;t_0\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if eps < -1.56e-4 or 1.60000000000000013e-4 < eps

    1. Initial program 48.4%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in x around 0 51.2%

      \[\leadsto \color{blue}{\cos \varepsilon - 1} \]

    if -1.56e-4 < eps < -2.45000000000000002e-147 or 3.19999999999999973e-144 < eps < 1.60000000000000013e-4

    1. Initial program 6.0%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in x around 0 6.0%

      \[\leadsto \color{blue}{\cos \varepsilon - 1} \]
    3. Taylor expanded in eps around 0 48.2%

      \[\leadsto \color{blue}{-0.5 \cdot {\varepsilon}^{2}} \]

    if -2.45000000000000002e-147 < eps < 3.19999999999999973e-144

    1. Initial program 39.3%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in eps around 0 98.9%

      \[\leadsto \color{blue}{-1 \cdot \left(\varepsilon \cdot \sin x\right)} \]
    3. Step-by-step derivation
      1. mul-1-neg98.9%

        \[\leadsto \color{blue}{-\varepsilon \cdot \sin x} \]
      2. *-commutative98.9%

        \[\leadsto -\color{blue}{\sin x \cdot \varepsilon} \]
      3. distribute-rgt-neg-in98.9%

        \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]
    4. Simplified98.9%

      \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]
    5. Taylor expanded in x around 0 51.4%

      \[\leadsto \color{blue}{-1 \cdot \left(\varepsilon \cdot x\right)} \]
    6. Step-by-step derivation
      1. mul-1-neg51.4%

        \[\leadsto \color{blue}{-\varepsilon \cdot x} \]
      2. distribute-rgt-neg-in51.4%

        \[\leadsto \color{blue}{\varepsilon \cdot \left(-x\right)} \]
    7. Simplified51.4%

      \[\leadsto \color{blue}{\varepsilon \cdot \left(-x\right)} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification50.6%

    \[\leadsto \begin{array}{l} \mathbf{if}\;\varepsilon \leq -0.000156:\\ \;\;\;\;\cos \varepsilon + -1\\ \mathbf{elif}\;\varepsilon \leq -2.45 \cdot 10^{-147}:\\ \;\;\;\;-0.5 \cdot {\varepsilon}^{2}\\ \mathbf{elif}\;\varepsilon \leq 3.2 \cdot 10^{-144}:\\ \;\;\;\;\varepsilon \cdot \left(-x\right)\\ \mathbf{elif}\;\varepsilon \leq 0.00016:\\ \;\;\;\;-0.5 \cdot {\varepsilon}^{2}\\ \mathbf{else}:\\ \;\;\;\;\cos \varepsilon + -1\\ \end{array} \]

Alternative 13: 65.5% accurate, 1.8× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \cos \varepsilon + -1\\ t_1 := \varepsilon \cdot \left(-\sin x\right)\\ \mathbf{if}\;\varepsilon \leq -0.0044:\\ \;\;\;\;t_0\\ \mathbf{elif}\;\varepsilon \leq 3 \cdot 10^{-101}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;\varepsilon \leq 7.5 \cdot 10^{-6}:\\ \;\;\;\;-0.5 \cdot {\varepsilon}^{2}\\ \mathbf{elif}\;\varepsilon \leq 1.9 \cdot 10^{-5}:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;t_0\\ \end{array} \end{array} \]
(FPCore (x eps)
 :precision binary64
 (let* ((t_0 (+ (cos eps) -1.0)) (t_1 (* eps (- (sin x)))))
   (if (<= eps -0.0044)
     t_0
     (if (<= eps 3e-101)
       t_1
       (if (<= eps 7.5e-6)
         (* -0.5 (pow eps 2.0))
         (if (<= eps 1.9e-5) t_1 t_0))))))
double code(double x, double eps) {
	double t_0 = cos(eps) + -1.0;
	double t_1 = eps * -sin(x);
	double tmp;
	if (eps <= -0.0044) {
		tmp = t_0;
	} else if (eps <= 3e-101) {
		tmp = t_1;
	} else if (eps <= 7.5e-6) {
		tmp = -0.5 * pow(eps, 2.0);
	} else if (eps <= 1.9e-5) {
		tmp = t_1;
	} else {
		tmp = t_0;
	}
	return tmp;
}
real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    real(8) :: t_0
    real(8) :: t_1
    real(8) :: tmp
    t_0 = cos(eps) + (-1.0d0)
    t_1 = eps * -sin(x)
    if (eps <= (-0.0044d0)) then
        tmp = t_0
    else if (eps <= 3d-101) then
        tmp = t_1
    else if (eps <= 7.5d-6) then
        tmp = (-0.5d0) * (eps ** 2.0d0)
    else if (eps <= 1.9d-5) then
        tmp = t_1
    else
        tmp = t_0
    end if
    code = tmp
end function
public static double code(double x, double eps) {
	double t_0 = Math.cos(eps) + -1.0;
	double t_1 = eps * -Math.sin(x);
	double tmp;
	if (eps <= -0.0044) {
		tmp = t_0;
	} else if (eps <= 3e-101) {
		tmp = t_1;
	} else if (eps <= 7.5e-6) {
		tmp = -0.5 * Math.pow(eps, 2.0);
	} else if (eps <= 1.9e-5) {
		tmp = t_1;
	} else {
		tmp = t_0;
	}
	return tmp;
}
def code(x, eps):
	t_0 = math.cos(eps) + -1.0
	t_1 = eps * -math.sin(x)
	tmp = 0
	if eps <= -0.0044:
		tmp = t_0
	elif eps <= 3e-101:
		tmp = t_1
	elif eps <= 7.5e-6:
		tmp = -0.5 * math.pow(eps, 2.0)
	elif eps <= 1.9e-5:
		tmp = t_1
	else:
		tmp = t_0
	return tmp
function code(x, eps)
	t_0 = Float64(cos(eps) + -1.0)
	t_1 = Float64(eps * Float64(-sin(x)))
	tmp = 0.0
	if (eps <= -0.0044)
		tmp = t_0;
	elseif (eps <= 3e-101)
		tmp = t_1;
	elseif (eps <= 7.5e-6)
		tmp = Float64(-0.5 * (eps ^ 2.0));
	elseif (eps <= 1.9e-5)
		tmp = t_1;
	else
		tmp = t_0;
	end
	return tmp
end
function tmp_2 = code(x, eps)
	t_0 = cos(eps) + -1.0;
	t_1 = eps * -sin(x);
	tmp = 0.0;
	if (eps <= -0.0044)
		tmp = t_0;
	elseif (eps <= 3e-101)
		tmp = t_1;
	elseif (eps <= 7.5e-6)
		tmp = -0.5 * (eps ^ 2.0);
	elseif (eps <= 1.9e-5)
		tmp = t_1;
	else
		tmp = t_0;
	end
	tmp_2 = tmp;
end
code[x_, eps_] := Block[{t$95$0 = N[(N[Cos[eps], $MachinePrecision] + -1.0), $MachinePrecision]}, Block[{t$95$1 = N[(eps * (-N[Sin[x], $MachinePrecision])), $MachinePrecision]}, If[LessEqual[eps, -0.0044], t$95$0, If[LessEqual[eps, 3e-101], t$95$1, If[LessEqual[eps, 7.5e-6], N[(-0.5 * N[Power[eps, 2.0], $MachinePrecision]), $MachinePrecision], If[LessEqual[eps, 1.9e-5], t$95$1, t$95$0]]]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \cos \varepsilon + -1\\
t_1 := \varepsilon \cdot \left(-\sin x\right)\\
\mathbf{if}\;\varepsilon \leq -0.0044:\\
\;\;\;\;t_0\\

\mathbf{elif}\;\varepsilon \leq 3 \cdot 10^{-101}:\\
\;\;\;\;t_1\\

\mathbf{elif}\;\varepsilon \leq 7.5 \cdot 10^{-6}:\\
\;\;\;\;-0.5 \cdot {\varepsilon}^{2}\\

\mathbf{elif}\;\varepsilon \leq 1.9 \cdot 10^{-5}:\\
\;\;\;\;t_1\\

\mathbf{else}:\\
\;\;\;\;t_0\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if eps < -0.00440000000000000027 or 1.9000000000000001e-5 < eps

    1. Initial program 48.8%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in x around 0 51.6%

      \[\leadsto \color{blue}{\cos \varepsilon - 1} \]

    if -0.00440000000000000027 < eps < 3.0000000000000003e-101 or 7.50000000000000019e-6 < eps < 1.9000000000000001e-5

    1. Initial program 26.8%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in eps around 0 84.8%

      \[\leadsto \color{blue}{-1 \cdot \left(\varepsilon \cdot \sin x\right)} \]
    3. Step-by-step derivation
      1. mul-1-neg84.8%

        \[\leadsto \color{blue}{-\varepsilon \cdot \sin x} \]
      2. *-commutative84.8%

        \[\leadsto -\color{blue}{\sin x \cdot \varepsilon} \]
      3. distribute-rgt-neg-in84.8%

        \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]
    4. Simplified84.8%

      \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]

    if 3.0000000000000003e-101 < eps < 7.50000000000000019e-6

    1. Initial program 4.2%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in x around 0 4.2%

      \[\leadsto \color{blue}{\cos \varepsilon - 1} \]
    3. Taylor expanded in eps around 0 65.8%

      \[\leadsto \color{blue}{-0.5 \cdot {\varepsilon}^{2}} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification66.1%

    \[\leadsto \begin{array}{l} \mathbf{if}\;\varepsilon \leq -0.0044:\\ \;\;\;\;\cos \varepsilon + -1\\ \mathbf{elif}\;\varepsilon \leq 3 \cdot 10^{-101}:\\ \;\;\;\;\varepsilon \cdot \left(-\sin x\right)\\ \mathbf{elif}\;\varepsilon \leq 7.5 \cdot 10^{-6}:\\ \;\;\;\;-0.5 \cdot {\varepsilon}^{2}\\ \mathbf{elif}\;\varepsilon \leq 1.9 \cdot 10^{-5}:\\ \;\;\;\;\varepsilon \cdot \left(-\sin x\right)\\ \mathbf{else}:\\ \;\;\;\;\cos \varepsilon + -1\\ \end{array} \]

Alternative 14: 43.5% accurate, 1.9× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;\varepsilon \leq -1.1 \cdot 10^{-46} \lor \neg \left(\varepsilon \leq 2.05 \cdot 10^{-71}\right):\\ \;\;\;\;\cos \varepsilon + -1\\ \mathbf{else}:\\ \;\;\;\;\varepsilon \cdot \left(-x\right)\\ \end{array} \end{array} \]
(FPCore (x eps)
 :precision binary64
 (if (or (<= eps -1.1e-46) (not (<= eps 2.05e-71)))
   (+ (cos eps) -1.0)
   (* eps (- x))))
double code(double x, double eps) {
	double tmp;
	if ((eps <= -1.1e-46) || !(eps <= 2.05e-71)) {
		tmp = cos(eps) + -1.0;
	} else {
		tmp = eps * -x;
	}
	return tmp;
}
real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    real(8) :: tmp
    if ((eps <= (-1.1d-46)) .or. (.not. (eps <= 2.05d-71))) then
        tmp = cos(eps) + (-1.0d0)
    else
        tmp = eps * -x
    end if
    code = tmp
end function
public static double code(double x, double eps) {
	double tmp;
	if ((eps <= -1.1e-46) || !(eps <= 2.05e-71)) {
		tmp = Math.cos(eps) + -1.0;
	} else {
		tmp = eps * -x;
	}
	return tmp;
}
def code(x, eps):
	tmp = 0
	if (eps <= -1.1e-46) or not (eps <= 2.05e-71):
		tmp = math.cos(eps) + -1.0
	else:
		tmp = eps * -x
	return tmp
function code(x, eps)
	tmp = 0.0
	if ((eps <= -1.1e-46) || !(eps <= 2.05e-71))
		tmp = Float64(cos(eps) + -1.0);
	else
		tmp = Float64(eps * Float64(-x));
	end
	return tmp
end
function tmp_2 = code(x, eps)
	tmp = 0.0;
	if ((eps <= -1.1e-46) || ~((eps <= 2.05e-71)))
		tmp = cos(eps) + -1.0;
	else
		tmp = eps * -x;
	end
	tmp_2 = tmp;
end
code[x_, eps_] := If[Or[LessEqual[eps, -1.1e-46], N[Not[LessEqual[eps, 2.05e-71]], $MachinePrecision]], N[(N[Cos[eps], $MachinePrecision] + -1.0), $MachinePrecision], N[(eps * (-x)), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;\varepsilon \leq -1.1 \cdot 10^{-46} \lor \neg \left(\varepsilon \leq 2.05 \cdot 10^{-71}\right):\\
\;\;\;\;\cos \varepsilon + -1\\

\mathbf{else}:\\
\;\;\;\;\varepsilon \cdot \left(-x\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if eps < -1.1e-46 or 2.04999999999999997e-71 < eps

    1. Initial program 43.9%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in x around 0 46.4%

      \[\leadsto \color{blue}{\cos \varepsilon - 1} \]

    if -1.1e-46 < eps < 2.04999999999999997e-71

    1. Initial program 27.4%

      \[\cos \left(x + \varepsilon\right) - \cos x \]
    2. Taylor expanded in eps around 0 83.4%

      \[\leadsto \color{blue}{-1 \cdot \left(\varepsilon \cdot \sin x\right)} \]
    3. Step-by-step derivation
      1. mul-1-neg83.4%

        \[\leadsto \color{blue}{-\varepsilon \cdot \sin x} \]
      2. *-commutative83.4%

        \[\leadsto -\color{blue}{\sin x \cdot \varepsilon} \]
      3. distribute-rgt-neg-in83.4%

        \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]
    4. Simplified83.4%

      \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]
    5. Taylor expanded in x around 0 38.6%

      \[\leadsto \color{blue}{-1 \cdot \left(\varepsilon \cdot x\right)} \]
    6. Step-by-step derivation
      1. mul-1-neg38.6%

        \[\leadsto \color{blue}{-\varepsilon \cdot x} \]
      2. distribute-rgt-neg-in38.6%

        \[\leadsto \color{blue}{\varepsilon \cdot \left(-x\right)} \]
    7. Simplified38.6%

      \[\leadsto \color{blue}{\varepsilon \cdot \left(-x\right)} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification43.2%

    \[\leadsto \begin{array}{l} \mathbf{if}\;\varepsilon \leq -1.1 \cdot 10^{-46} \lor \neg \left(\varepsilon \leq 2.05 \cdot 10^{-71}\right):\\ \;\;\;\;\cos \varepsilon + -1\\ \mathbf{else}:\\ \;\;\;\;\varepsilon \cdot \left(-x\right)\\ \end{array} \]

Alternative 15: 17.8% accurate, 51.3× speedup?

\[\begin{array}{l} \\ \varepsilon \cdot \left(-x\right) \end{array} \]
(FPCore (x eps) :precision binary64 (* eps (- x)))
double code(double x, double eps) {
	return eps * -x;
}
real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    code = eps * -x
end function
public static double code(double x, double eps) {
	return eps * -x;
}
def code(x, eps):
	return eps * -x
function code(x, eps)
	return Float64(eps * Float64(-x))
end
function tmp = code(x, eps)
	tmp = eps * -x;
end
code[x_, eps_] := N[(eps * (-x)), $MachinePrecision]
\begin{array}{l}

\\
\varepsilon \cdot \left(-x\right)
\end{array}
Derivation
  1. Initial program 37.2%

    \[\cos \left(x + \varepsilon\right) - \cos x \]
  2. Taylor expanded in eps around 0 39.1%

    \[\leadsto \color{blue}{-1 \cdot \left(\varepsilon \cdot \sin x\right)} \]
  3. Step-by-step derivation
    1. mul-1-neg39.1%

      \[\leadsto \color{blue}{-\varepsilon \cdot \sin x} \]
    2. *-commutative39.1%

      \[\leadsto -\color{blue}{\sin x \cdot \varepsilon} \]
    3. distribute-rgt-neg-in39.1%

      \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]
  4. Simplified39.1%

    \[\leadsto \color{blue}{\sin x \cdot \left(-\varepsilon\right)} \]
  5. Taylor expanded in x around 0 17.5%

    \[\leadsto \color{blue}{-1 \cdot \left(\varepsilon \cdot x\right)} \]
  6. Step-by-step derivation
    1. mul-1-neg17.5%

      \[\leadsto \color{blue}{-\varepsilon \cdot x} \]
    2. distribute-rgt-neg-in17.5%

      \[\leadsto \color{blue}{\varepsilon \cdot \left(-x\right)} \]
  7. Simplified17.5%

    \[\leadsto \color{blue}{\varepsilon \cdot \left(-x\right)} \]
  8. Final simplification17.5%

    \[\leadsto \varepsilon \cdot \left(-x\right) \]

Reproduce

?
herbie shell --seed 2023322 
(FPCore (x eps)
  :name "2cos (problem 3.3.5)"
  :precision binary64
  (- (cos (+ x eps)) (cos x)))