Migdal et al, Equation (64)

Percentage Accurate: 99.5% → 99.6%
Time: 10.4s
Alternatives: 9
Speedup: 2.0×

Specification

?
\[\begin{array}{l} \\ \begin{array}{l} t_1 := \frac{\cos th}{\sqrt{2}}\\ t_1 \cdot \left(a1 \cdot a1\right) + t_1 \cdot \left(a2 \cdot a2\right) \end{array} \end{array} \]
(FPCore (a1 a2 th)
 :precision binary64
 (let* ((t_1 (/ (cos th) (sqrt 2.0))))
   (+ (* t_1 (* a1 a1)) (* t_1 (* a2 a2)))))
double code(double a1, double a2, double th) {
	double t_1 = cos(th) / sqrt(2.0);
	return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
}
real(8) function code(a1, a2, th)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2
    real(8), intent (in) :: th
    real(8) :: t_1
    t_1 = cos(th) / sqrt(2.0d0)
    code = (t_1 * (a1 * a1)) + (t_1 * (a2 * a2))
end function
public static double code(double a1, double a2, double th) {
	double t_1 = Math.cos(th) / Math.sqrt(2.0);
	return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
}
def code(a1, a2, th):
	t_1 = math.cos(th) / math.sqrt(2.0)
	return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2))
function code(a1, a2, th)
	t_1 = Float64(cos(th) / sqrt(2.0))
	return Float64(Float64(t_1 * Float64(a1 * a1)) + Float64(t_1 * Float64(a2 * a2)))
end
function tmp = code(a1, a2, th)
	t_1 = cos(th) / sqrt(2.0);
	tmp = (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
end
code[a1_, a2_, th_] := Block[{t$95$1 = N[(N[Cos[th], $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]}, N[(N[(t$95$1 * N[(a1 * a1), $MachinePrecision]), $MachinePrecision] + N[(t$95$1 * N[(a2 * a2), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
t_1 := \frac{\cos th}{\sqrt{2}}\\
t_1 \cdot \left(a1 \cdot a1\right) + t_1 \cdot \left(a2 \cdot a2\right)
\end{array}
\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 9 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: 99.5% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_1 := \frac{\cos th}{\sqrt{2}}\\ t_1 \cdot \left(a1 \cdot a1\right) + t_1 \cdot \left(a2 \cdot a2\right) \end{array} \end{array} \]
(FPCore (a1 a2 th)
 :precision binary64
 (let* ((t_1 (/ (cos th) (sqrt 2.0))))
   (+ (* t_1 (* a1 a1)) (* t_1 (* a2 a2)))))
double code(double a1, double a2, double th) {
	double t_1 = cos(th) / sqrt(2.0);
	return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
}
real(8) function code(a1, a2, th)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2
    real(8), intent (in) :: th
    real(8) :: t_1
    t_1 = cos(th) / sqrt(2.0d0)
    code = (t_1 * (a1 * a1)) + (t_1 * (a2 * a2))
end function
public static double code(double a1, double a2, double th) {
	double t_1 = Math.cos(th) / Math.sqrt(2.0);
	return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
}
def code(a1, a2, th):
	t_1 = math.cos(th) / math.sqrt(2.0)
	return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2))
function code(a1, a2, th)
	t_1 = Float64(cos(th) / sqrt(2.0))
	return Float64(Float64(t_1 * Float64(a1 * a1)) + Float64(t_1 * Float64(a2 * a2)))
end
function tmp = code(a1, a2, th)
	t_1 = cos(th) / sqrt(2.0);
	tmp = (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
end
code[a1_, a2_, th_] := Block[{t$95$1 = N[(N[Cos[th], $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]}, N[(N[(t$95$1 * N[(a1 * a1), $MachinePrecision]), $MachinePrecision] + N[(t$95$1 * N[(a2 * a2), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
t_1 := \frac{\cos th}{\sqrt{2}}\\
t_1 \cdot \left(a1 \cdot a1\right) + t_1 \cdot \left(a2 \cdot a2\right)
\end{array}
\end{array}

Alternative 1: 99.6% accurate, 0.7× speedup?

\[\begin{array}{l} a2_m = \left|a2\right| \\ [a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\ \\ \begin{array}{l} t_1 := \frac{\sqrt{2}}{\cos th}\\ \mathsf{fma}\left(\frac{a2_m}{t_1}, a2_m, \frac{{a1}^{2}}{t_1}\right) \end{array} \end{array} \]
a2_m = (fabs.f64 a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
(FPCore (a1 a2_m th)
 :precision binary64
 (let* ((t_1 (/ (sqrt 2.0) (cos th))))
   (fma (/ a2_m t_1) a2_m (/ (pow a1 2.0) t_1))))
a2_m = fabs(a2);
assert(a1 < a2_m && a2_m < th);
double code(double a1, double a2_m, double th) {
	double t_1 = sqrt(2.0) / cos(th);
	return fma((a2_m / t_1), a2_m, (pow(a1, 2.0) / t_1));
}
a2_m = abs(a2)
a1, a2_m, th = sort([a1, a2_m, th])
function code(a1, a2_m, th)
	t_1 = Float64(sqrt(2.0) / cos(th))
	return fma(Float64(a2_m / t_1), a2_m, Float64((a1 ^ 2.0) / t_1))
end
a2_m = N[Abs[a2], $MachinePrecision]
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
code[a1_, a2$95$m_, th_] := Block[{t$95$1 = N[(N[Sqrt[2.0], $MachinePrecision] / N[Cos[th], $MachinePrecision]), $MachinePrecision]}, N[(N[(a2$95$m / t$95$1), $MachinePrecision] * a2$95$m + N[(N[Power[a1, 2.0], $MachinePrecision] / t$95$1), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
a2_m = \left|a2\right|
\\
[a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\
\\
\begin{array}{l}
t_1 := \frac{\sqrt{2}}{\cos th}\\
\mathsf{fma}\left(\frac{a2_m}{t_1}, a2_m, \frac{{a1}^{2}}{t_1}\right)
\end{array}
\end{array}
Derivation
  1. Initial program 99.5%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Step-by-step derivation
    1. distribute-lft-out99.5%

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  3. Simplified99.5%

    \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  4. Step-by-step derivation
    1. +-commutative99.5%

      \[\leadsto \frac{\cos th}{\sqrt{2}} \cdot \color{blue}{\left(a2 \cdot a2 + a1 \cdot a1\right)} \]
    2. distribute-lft-in99.5%

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right)} \]
    3. associate-*r*99.6%

      \[\leadsto \color{blue}{\left(\frac{\cos th}{\sqrt{2}} \cdot a2\right) \cdot a2} + \frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) \]
    4. fma-def99.6%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\frac{\cos th}{\sqrt{2}} \cdot a2, a2, \frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right)\right)} \]
    5. clear-num99.5%

      \[\leadsto \mathsf{fma}\left(\color{blue}{\frac{1}{\frac{\sqrt{2}}{\cos th}}} \cdot a2, a2, \frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right)\right) \]
    6. associate-*l/99.6%

      \[\leadsto \mathsf{fma}\left(\color{blue}{\frac{1 \cdot a2}{\frac{\sqrt{2}}{\cos th}}}, a2, \frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right)\right) \]
    7. *-un-lft-identity99.6%

      \[\leadsto \mathsf{fma}\left(\frac{\color{blue}{a2}}{\frac{\sqrt{2}}{\cos th}}, a2, \frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right)\right) \]
    8. *-commutative99.6%

      \[\leadsto \mathsf{fma}\left(\frac{a2}{\frac{\sqrt{2}}{\cos th}}, a2, \color{blue}{\left(a1 \cdot a1\right) \cdot \frac{\cos th}{\sqrt{2}}}\right) \]
    9. clear-num99.6%

      \[\leadsto \mathsf{fma}\left(\frac{a2}{\frac{\sqrt{2}}{\cos th}}, a2, \left(a1 \cdot a1\right) \cdot \color{blue}{\frac{1}{\frac{\sqrt{2}}{\cos th}}}\right) \]
    10. un-div-inv99.6%

      \[\leadsto \mathsf{fma}\left(\frac{a2}{\frac{\sqrt{2}}{\cos th}}, a2, \color{blue}{\frac{a1 \cdot a1}{\frac{\sqrt{2}}{\cos th}}}\right) \]
    11. pow299.6%

      \[\leadsto \mathsf{fma}\left(\frac{a2}{\frac{\sqrt{2}}{\cos th}}, a2, \frac{\color{blue}{{a1}^{2}}}{\frac{\sqrt{2}}{\cos th}}\right) \]
  5. Applied egg-rr99.6%

    \[\leadsto \color{blue}{\mathsf{fma}\left(\frac{a2}{\frac{\sqrt{2}}{\cos th}}, a2, \frac{{a1}^{2}}{\frac{\sqrt{2}}{\cos th}}\right)} \]
  6. Final simplification99.6%

    \[\leadsto \mathsf{fma}\left(\frac{a2}{\frac{\sqrt{2}}{\cos th}}, a2, \frac{{a1}^{2}}{\frac{\sqrt{2}}{\cos th}}\right) \]

Alternative 2: 99.6% accurate, 1.0× speedup?

\[\begin{array}{l} a2_m = \left|a2\right| \\ [a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\ \\ \cos th \cdot \frac{{\left(\mathsf{hypot}\left(a1, a2_m\right)\right)}^{2}}{\sqrt{2}} \end{array} \]
a2_m = (fabs.f64 a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
(FPCore (a1 a2_m th)
 :precision binary64
 (* (cos th) (/ (pow (hypot a1 a2_m) 2.0) (sqrt 2.0))))
a2_m = fabs(a2);
assert(a1 < a2_m && a2_m < th);
double code(double a1, double a2_m, double th) {
	return cos(th) * (pow(hypot(a1, a2_m), 2.0) / sqrt(2.0));
}
a2_m = Math.abs(a2);
assert a1 < a2_m && a2_m < th;
public static double code(double a1, double a2_m, double th) {
	return Math.cos(th) * (Math.pow(Math.hypot(a1, a2_m), 2.0) / Math.sqrt(2.0));
}
a2_m = math.fabs(a2)
[a1, a2_m, th] = sort([a1, a2_m, th])
def code(a1, a2_m, th):
	return math.cos(th) * (math.pow(math.hypot(a1, a2_m), 2.0) / math.sqrt(2.0))
a2_m = abs(a2)
a1, a2_m, th = sort([a1, a2_m, th])
function code(a1, a2_m, th)
	return Float64(cos(th) * Float64((hypot(a1, a2_m) ^ 2.0) / sqrt(2.0)))
end
a2_m = abs(a2);
a1, a2_m, th = num2cell(sort([a1, a2_m, th])){:}
function tmp = code(a1, a2_m, th)
	tmp = cos(th) * ((hypot(a1, a2_m) ^ 2.0) / sqrt(2.0));
end
a2_m = N[Abs[a2], $MachinePrecision]
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
code[a1_, a2$95$m_, th_] := N[(N[Cos[th], $MachinePrecision] * N[(N[Power[N[Sqrt[a1 ^ 2 + a2$95$m ^ 2], $MachinePrecision], 2.0], $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
a2_m = \left|a2\right|
\\
[a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\
\\
\cos th \cdot \frac{{\left(\mathsf{hypot}\left(a1, a2_m\right)\right)}^{2}}{\sqrt{2}}
\end{array}
Derivation
  1. Initial program 99.5%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Step-by-step derivation
    1. distribute-lft-out99.5%

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  3. Simplified99.5%

    \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  4. Step-by-step derivation
    1. expm1-log1p-u79.3%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)\right)\right)} \]
    2. expm1-udef58.0%

      \[\leadsto \color{blue}{e^{\mathsf{log1p}\left(\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)\right)} - 1} \]
    3. add-sqr-sqrt58.0%

      \[\leadsto e^{\mathsf{log1p}\left(\frac{\cos th}{\sqrt{2}} \cdot \color{blue}{\left(\sqrt{a1 \cdot a1 + a2 \cdot a2} \cdot \sqrt{a1 \cdot a1 + a2 \cdot a2}\right)}\right)} - 1 \]
    4. pow258.0%

      \[\leadsto e^{\mathsf{log1p}\left(\frac{\cos th}{\sqrt{2}} \cdot \color{blue}{{\left(\sqrt{a1 \cdot a1 + a2 \cdot a2}\right)}^{2}}\right)} - 1 \]
    5. hypot-def58.0%

      \[\leadsto e^{\mathsf{log1p}\left(\frac{\cos th}{\sqrt{2}} \cdot {\color{blue}{\left(\mathsf{hypot}\left(a1, a2\right)\right)}}^{2}\right)} - 1 \]
  5. Applied egg-rr58.0%

    \[\leadsto \color{blue}{e^{\mathsf{log1p}\left(\frac{\cos th}{\sqrt{2}} \cdot {\left(\mathsf{hypot}\left(a1, a2\right)\right)}^{2}\right)} - 1} \]
  6. Step-by-step derivation
    1. expm1-def79.3%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\frac{\cos th}{\sqrt{2}} \cdot {\left(\mathsf{hypot}\left(a1, a2\right)\right)}^{2}\right)\right)} \]
    2. expm1-log1p99.5%

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot {\left(\mathsf{hypot}\left(a1, a2\right)\right)}^{2}} \]
    3. *-commutative99.5%

      \[\leadsto \color{blue}{{\left(\mathsf{hypot}\left(a1, a2\right)\right)}^{2} \cdot \frac{\cos th}{\sqrt{2}}} \]
    4. associate-*r/99.6%

      \[\leadsto \color{blue}{\frac{{\left(\mathsf{hypot}\left(a1, a2\right)\right)}^{2} \cdot \cos th}{\sqrt{2}}} \]
    5. associate-*l/99.6%

      \[\leadsto \color{blue}{\frac{{\left(\mathsf{hypot}\left(a1, a2\right)\right)}^{2}}{\sqrt{2}} \cdot \cos th} \]
    6. *-commutative99.6%

      \[\leadsto \color{blue}{\cos th \cdot \frac{{\left(\mathsf{hypot}\left(a1, a2\right)\right)}^{2}}{\sqrt{2}}} \]
  7. Simplified99.6%

    \[\leadsto \color{blue}{\cos th \cdot \frac{{\left(\mathsf{hypot}\left(a1, a2\right)\right)}^{2}}{\sqrt{2}}} \]
  8. Final simplification99.6%

    \[\leadsto \cos th \cdot \frac{{\left(\mathsf{hypot}\left(a1, a2\right)\right)}^{2}}{\sqrt{2}} \]

Alternative 3: 99.6% accurate, 2.0× speedup?

\[\begin{array}{l} a2_m = \left|a2\right| \\ [a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\ \\ \left(\cos th \cdot {2}^{-0.5}\right) \cdot \left(a1 \cdot a1 + a2_m \cdot a2_m\right) \end{array} \]
a2_m = (fabs.f64 a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
(FPCore (a1 a2_m th)
 :precision binary64
 (* (* (cos th) (pow 2.0 -0.5)) (+ (* a1 a1) (* a2_m a2_m))))
a2_m = fabs(a2);
assert(a1 < a2_m && a2_m < th);
double code(double a1, double a2_m, double th) {
	return (cos(th) * pow(2.0, -0.5)) * ((a1 * a1) + (a2_m * a2_m));
}
a2_m = abs(a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
real(8) function code(a1, a2_m, th)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2_m
    real(8), intent (in) :: th
    code = (cos(th) * (2.0d0 ** (-0.5d0))) * ((a1 * a1) + (a2_m * a2_m))
end function
a2_m = Math.abs(a2);
assert a1 < a2_m && a2_m < th;
public static double code(double a1, double a2_m, double th) {
	return (Math.cos(th) * Math.pow(2.0, -0.5)) * ((a1 * a1) + (a2_m * a2_m));
}
a2_m = math.fabs(a2)
[a1, a2_m, th] = sort([a1, a2_m, th])
def code(a1, a2_m, th):
	return (math.cos(th) * math.pow(2.0, -0.5)) * ((a1 * a1) + (a2_m * a2_m))
a2_m = abs(a2)
a1, a2_m, th = sort([a1, a2_m, th])
function code(a1, a2_m, th)
	return Float64(Float64(cos(th) * (2.0 ^ -0.5)) * Float64(Float64(a1 * a1) + Float64(a2_m * a2_m)))
end
a2_m = abs(a2);
a1, a2_m, th = num2cell(sort([a1, a2_m, th])){:}
function tmp = code(a1, a2_m, th)
	tmp = (cos(th) * (2.0 ^ -0.5)) * ((a1 * a1) + (a2_m * a2_m));
end
a2_m = N[Abs[a2], $MachinePrecision]
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
code[a1_, a2$95$m_, th_] := N[(N[(N[Cos[th], $MachinePrecision] * N[Power[2.0, -0.5], $MachinePrecision]), $MachinePrecision] * N[(N[(a1 * a1), $MachinePrecision] + N[(a2$95$m * a2$95$m), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
a2_m = \left|a2\right|
\\
[a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\
\\
\left(\cos th \cdot {2}^{-0.5}\right) \cdot \left(a1 \cdot a1 + a2_m \cdot a2_m\right)
\end{array}
Derivation
  1. Initial program 99.5%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Step-by-step derivation
    1. distribute-lft-out99.5%

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  3. Simplified99.5%

    \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  4. Step-by-step derivation
    1. clear-num99.5%

      \[\leadsto \color{blue}{\frac{1}{\frac{\sqrt{2}}{\cos th}}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    2. associate-/r/99.5%

      \[\leadsto \color{blue}{\left(\frac{1}{\sqrt{2}} \cdot \cos th\right)} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    3. pow1/299.5%

      \[\leadsto \left(\frac{1}{\color{blue}{{2}^{0.5}}} \cdot \cos th\right) \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    4. pow-flip99.5%

      \[\leadsto \left(\color{blue}{{2}^{\left(-0.5\right)}} \cdot \cos th\right) \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    5. metadata-eval99.5%

      \[\leadsto \left({2}^{\color{blue}{-0.5}} \cdot \cos th\right) \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
  5. Applied egg-rr99.5%

    \[\leadsto \color{blue}{\left({2}^{-0.5} \cdot \cos th\right)} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
  6. Final simplification99.5%

    \[\leadsto \left(\cos th \cdot {2}^{-0.5}\right) \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]

Alternative 4: 99.5% accurate, 2.0× speedup?

\[\begin{array}{l} a2_m = \left|a2\right| \\ [a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\ \\ \left(a1 \cdot a1 + a2_m \cdot a2_m\right) \cdot \frac{\cos th}{\sqrt{2}} \end{array} \]
a2_m = (fabs.f64 a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
(FPCore (a1 a2_m th)
 :precision binary64
 (* (+ (* a1 a1) (* a2_m a2_m)) (/ (cos th) (sqrt 2.0))))
a2_m = fabs(a2);
assert(a1 < a2_m && a2_m < th);
double code(double a1, double a2_m, double th) {
	return ((a1 * a1) + (a2_m * a2_m)) * (cos(th) / sqrt(2.0));
}
a2_m = abs(a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
real(8) function code(a1, a2_m, th)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2_m
    real(8), intent (in) :: th
    code = ((a1 * a1) + (a2_m * a2_m)) * (cos(th) / sqrt(2.0d0))
end function
a2_m = Math.abs(a2);
assert a1 < a2_m && a2_m < th;
public static double code(double a1, double a2_m, double th) {
	return ((a1 * a1) + (a2_m * a2_m)) * (Math.cos(th) / Math.sqrt(2.0));
}
a2_m = math.fabs(a2)
[a1, a2_m, th] = sort([a1, a2_m, th])
def code(a1, a2_m, th):
	return ((a1 * a1) + (a2_m * a2_m)) * (math.cos(th) / math.sqrt(2.0))
a2_m = abs(a2)
a1, a2_m, th = sort([a1, a2_m, th])
function code(a1, a2_m, th)
	return Float64(Float64(Float64(a1 * a1) + Float64(a2_m * a2_m)) * Float64(cos(th) / sqrt(2.0)))
end
a2_m = abs(a2);
a1, a2_m, th = num2cell(sort([a1, a2_m, th])){:}
function tmp = code(a1, a2_m, th)
	tmp = ((a1 * a1) + (a2_m * a2_m)) * (cos(th) / sqrt(2.0));
end
a2_m = N[Abs[a2], $MachinePrecision]
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
code[a1_, a2$95$m_, th_] := N[(N[(N[(a1 * a1), $MachinePrecision] + N[(a2$95$m * a2$95$m), $MachinePrecision]), $MachinePrecision] * N[(N[Cos[th], $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
a2_m = \left|a2\right|
\\
[a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\
\\
\left(a1 \cdot a1 + a2_m \cdot a2_m\right) \cdot \frac{\cos th}{\sqrt{2}}
\end{array}
Derivation
  1. Initial program 99.5%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Step-by-step derivation
    1. distribute-lft-out99.5%

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  3. Simplified99.5%

    \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  4. Final simplification99.5%

    \[\leadsto \left(a1 \cdot a1 + a2 \cdot a2\right) \cdot \frac{\cos th}{\sqrt{2}} \]

Alternative 5: 77.8% accurate, 2.0× speedup?

\[\begin{array}{l} a2_m = \left|a2\right| \\ [a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\ \\ \frac{a2_m \cdot \sqrt{0.5}}{\frac{1}{a2_m \cdot \cos th}} \end{array} \]
a2_m = (fabs.f64 a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
(FPCore (a1 a2_m th)
 :precision binary64
 (/ (* a2_m (sqrt 0.5)) (/ 1.0 (* a2_m (cos th)))))
a2_m = fabs(a2);
assert(a1 < a2_m && a2_m < th);
double code(double a1, double a2_m, double th) {
	return (a2_m * sqrt(0.5)) / (1.0 / (a2_m * cos(th)));
}
a2_m = abs(a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
real(8) function code(a1, a2_m, th)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2_m
    real(8), intent (in) :: th
    code = (a2_m * sqrt(0.5d0)) / (1.0d0 / (a2_m * cos(th)))
end function
a2_m = Math.abs(a2);
assert a1 < a2_m && a2_m < th;
public static double code(double a1, double a2_m, double th) {
	return (a2_m * Math.sqrt(0.5)) / (1.0 / (a2_m * Math.cos(th)));
}
a2_m = math.fabs(a2)
[a1, a2_m, th] = sort([a1, a2_m, th])
def code(a1, a2_m, th):
	return (a2_m * math.sqrt(0.5)) / (1.0 / (a2_m * math.cos(th)))
a2_m = abs(a2)
a1, a2_m, th = sort([a1, a2_m, th])
function code(a1, a2_m, th)
	return Float64(Float64(a2_m * sqrt(0.5)) / Float64(1.0 / Float64(a2_m * cos(th))))
end
a2_m = abs(a2);
a1, a2_m, th = num2cell(sort([a1, a2_m, th])){:}
function tmp = code(a1, a2_m, th)
	tmp = (a2_m * sqrt(0.5)) / (1.0 / (a2_m * cos(th)));
end
a2_m = N[Abs[a2], $MachinePrecision]
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
code[a1_, a2$95$m_, th_] := N[(N[(a2$95$m * N[Sqrt[0.5], $MachinePrecision]), $MachinePrecision] / N[(1.0 / N[(a2$95$m * N[Cos[th], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
a2_m = \left|a2\right|
\\
[a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\
\\
\frac{a2_m \cdot \sqrt{0.5}}{\frac{1}{a2_m \cdot \cos th}}
\end{array}
Derivation
  1. Initial program 99.5%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Step-by-step derivation
    1. distribute-lft-out99.5%

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  3. Simplified99.5%

    \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  4. Taylor expanded in a1 around 0 57.1%

    \[\leadsto \color{blue}{\frac{{a2}^{2} \cdot \cos th}{\sqrt{2}}} \]
  5. Step-by-step derivation
    1. pow257.1%

      \[\leadsto \frac{\color{blue}{\left(a2 \cdot a2\right)} \cdot \cos th}{\sqrt{2}} \]
    2. associate-/l*57.1%

      \[\leadsto \color{blue}{\frac{a2 \cdot a2}{\frac{\sqrt{2}}{\cos th}}} \]
    3. associate-*l/57.1%

      \[\leadsto \color{blue}{\frac{a2}{\frac{\sqrt{2}}{\cos th}} \cdot a2} \]
    4. associate-/r/57.1%

      \[\leadsto \color{blue}{\left(\frac{a2}{\sqrt{2}} \cdot \cos th\right)} \cdot a2 \]
    5. associate-*l*57.1%

      \[\leadsto \color{blue}{\frac{a2}{\sqrt{2}} \cdot \left(\cos th \cdot a2\right)} \]
    6. div-inv57.0%

      \[\leadsto \color{blue}{\left(a2 \cdot \frac{1}{\sqrt{2}}\right)} \cdot \left(\cos th \cdot a2\right) \]
    7. add-sqr-sqrt57.0%

      \[\leadsto \left(a2 \cdot \color{blue}{\left(\sqrt{\frac{1}{\sqrt{2}}} \cdot \sqrt{\frac{1}{\sqrt{2}}}\right)}\right) \cdot \left(\cos th \cdot a2\right) \]
    8. sqrt-unprod57.0%

      \[\leadsto \left(a2 \cdot \color{blue}{\sqrt{\frac{1}{\sqrt{2}} \cdot \frac{1}{\sqrt{2}}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    9. frac-times57.0%

      \[\leadsto \left(a2 \cdot \sqrt{\color{blue}{\frac{1 \cdot 1}{\sqrt{2} \cdot \sqrt{2}}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    10. metadata-eval57.0%

      \[\leadsto \left(a2 \cdot \sqrt{\frac{\color{blue}{1}}{\sqrt{2} \cdot \sqrt{2}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    11. rem-square-sqrt57.1%

      \[\leadsto \left(a2 \cdot \sqrt{\frac{1}{\color{blue}{2}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    12. metadata-eval57.1%

      \[\leadsto \left(a2 \cdot \sqrt{\color{blue}{0.5}}\right) \cdot \left(\cos th \cdot a2\right) \]
  6. Applied egg-rr57.1%

    \[\leadsto \color{blue}{\left(a2 \cdot \sqrt{0.5}\right) \cdot \left(\cos th \cdot a2\right)} \]
  7. Step-by-step derivation
    1. *-commutative57.1%

      \[\leadsto \left(a2 \cdot \sqrt{0.5}\right) \cdot \color{blue}{\left(a2 \cdot \cos th\right)} \]
    2. /-rgt-identity57.1%

      \[\leadsto \left(a2 \cdot \sqrt{0.5}\right) \cdot \left(\color{blue}{\frac{a2}{1}} \cdot \cos th\right) \]
    3. associate-/r/57.0%

      \[\leadsto \left(a2 \cdot \sqrt{0.5}\right) \cdot \color{blue}{\frac{a2}{\frac{1}{\cos th}}} \]
    4. clear-num57.0%

      \[\leadsto \left(a2 \cdot \sqrt{0.5}\right) \cdot \color{blue}{\frac{1}{\frac{\frac{1}{\cos th}}{a2}}} \]
    5. un-div-inv57.0%

      \[\leadsto \color{blue}{\frac{a2 \cdot \sqrt{0.5}}{\frac{\frac{1}{\cos th}}{a2}}} \]
    6. associate-/l/57.0%

      \[\leadsto \frac{a2 \cdot \sqrt{0.5}}{\color{blue}{\frac{1}{a2 \cdot \cos th}}} \]
    7. *-commutative57.0%

      \[\leadsto \frac{a2 \cdot \sqrt{0.5}}{\frac{1}{\color{blue}{\cos th \cdot a2}}} \]
  8. Applied egg-rr57.0%

    \[\leadsto \color{blue}{\frac{a2 \cdot \sqrt{0.5}}{\frac{1}{\cos th \cdot a2}}} \]
  9. Final simplification57.0%

    \[\leadsto \frac{a2 \cdot \sqrt{0.5}}{\frac{1}{a2 \cdot \cos th}} \]

Alternative 6: 77.9% accurate, 2.0× speedup?

\[\begin{array}{l} a2_m = \left|a2\right| \\ [a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\ \\ \left(a2_m \cdot \sqrt{0.5}\right) \cdot \left(a2_m \cdot \cos th\right) \end{array} \]
a2_m = (fabs.f64 a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
(FPCore (a1 a2_m th)
 :precision binary64
 (* (* a2_m (sqrt 0.5)) (* a2_m (cos th))))
a2_m = fabs(a2);
assert(a1 < a2_m && a2_m < th);
double code(double a1, double a2_m, double th) {
	return (a2_m * sqrt(0.5)) * (a2_m * cos(th));
}
a2_m = abs(a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
real(8) function code(a1, a2_m, th)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2_m
    real(8), intent (in) :: th
    code = (a2_m * sqrt(0.5d0)) * (a2_m * cos(th))
end function
a2_m = Math.abs(a2);
assert a1 < a2_m && a2_m < th;
public static double code(double a1, double a2_m, double th) {
	return (a2_m * Math.sqrt(0.5)) * (a2_m * Math.cos(th));
}
a2_m = math.fabs(a2)
[a1, a2_m, th] = sort([a1, a2_m, th])
def code(a1, a2_m, th):
	return (a2_m * math.sqrt(0.5)) * (a2_m * math.cos(th))
a2_m = abs(a2)
a1, a2_m, th = sort([a1, a2_m, th])
function code(a1, a2_m, th)
	return Float64(Float64(a2_m * sqrt(0.5)) * Float64(a2_m * cos(th)))
end
a2_m = abs(a2);
a1, a2_m, th = num2cell(sort([a1, a2_m, th])){:}
function tmp = code(a1, a2_m, th)
	tmp = (a2_m * sqrt(0.5)) * (a2_m * cos(th));
end
a2_m = N[Abs[a2], $MachinePrecision]
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
code[a1_, a2$95$m_, th_] := N[(N[(a2$95$m * N[Sqrt[0.5], $MachinePrecision]), $MachinePrecision] * N[(a2$95$m * N[Cos[th], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
a2_m = \left|a2\right|
\\
[a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\
\\
\left(a2_m \cdot \sqrt{0.5}\right) \cdot \left(a2_m \cdot \cos th\right)
\end{array}
Derivation
  1. Initial program 99.5%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Step-by-step derivation
    1. distribute-lft-out99.5%

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  3. Simplified99.5%

    \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  4. Taylor expanded in a1 around 0 57.1%

    \[\leadsto \color{blue}{\frac{{a2}^{2} \cdot \cos th}{\sqrt{2}}} \]
  5. Step-by-step derivation
    1. pow257.1%

      \[\leadsto \frac{\color{blue}{\left(a2 \cdot a2\right)} \cdot \cos th}{\sqrt{2}} \]
    2. associate-/l*57.1%

      \[\leadsto \color{blue}{\frac{a2 \cdot a2}{\frac{\sqrt{2}}{\cos th}}} \]
    3. associate-*l/57.1%

      \[\leadsto \color{blue}{\frac{a2}{\frac{\sqrt{2}}{\cos th}} \cdot a2} \]
    4. associate-/r/57.1%

      \[\leadsto \color{blue}{\left(\frac{a2}{\sqrt{2}} \cdot \cos th\right)} \cdot a2 \]
    5. associate-*l*57.1%

      \[\leadsto \color{blue}{\frac{a2}{\sqrt{2}} \cdot \left(\cos th \cdot a2\right)} \]
    6. div-inv57.0%

      \[\leadsto \color{blue}{\left(a2 \cdot \frac{1}{\sqrt{2}}\right)} \cdot \left(\cos th \cdot a2\right) \]
    7. add-sqr-sqrt57.0%

      \[\leadsto \left(a2 \cdot \color{blue}{\left(\sqrt{\frac{1}{\sqrt{2}}} \cdot \sqrt{\frac{1}{\sqrt{2}}}\right)}\right) \cdot \left(\cos th \cdot a2\right) \]
    8. sqrt-unprod57.0%

      \[\leadsto \left(a2 \cdot \color{blue}{\sqrt{\frac{1}{\sqrt{2}} \cdot \frac{1}{\sqrt{2}}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    9. frac-times57.0%

      \[\leadsto \left(a2 \cdot \sqrt{\color{blue}{\frac{1 \cdot 1}{\sqrt{2} \cdot \sqrt{2}}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    10. metadata-eval57.0%

      \[\leadsto \left(a2 \cdot \sqrt{\frac{\color{blue}{1}}{\sqrt{2} \cdot \sqrt{2}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    11. rem-square-sqrt57.1%

      \[\leadsto \left(a2 \cdot \sqrt{\frac{1}{\color{blue}{2}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    12. metadata-eval57.1%

      \[\leadsto \left(a2 \cdot \sqrt{\color{blue}{0.5}}\right) \cdot \left(\cos th \cdot a2\right) \]
  6. Applied egg-rr57.1%

    \[\leadsto \color{blue}{\left(a2 \cdot \sqrt{0.5}\right) \cdot \left(\cos th \cdot a2\right)} \]
  7. Final simplification57.1%

    \[\leadsto \left(a2 \cdot \sqrt{0.5}\right) \cdot \left(a2 \cdot \cos th\right) \]

Alternative 7: 66.1% accurate, 3.8× speedup?

\[\begin{array}{l} a2_m = \left|a2\right| \\ [a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\ \\ \left(a1 \cdot a1 + a2_m \cdot a2_m\right) \cdot \sqrt{0.5} \end{array} \]
a2_m = (fabs.f64 a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
(FPCore (a1 a2_m th)
 :precision binary64
 (* (+ (* a1 a1) (* a2_m a2_m)) (sqrt 0.5)))
a2_m = fabs(a2);
assert(a1 < a2_m && a2_m < th);
double code(double a1, double a2_m, double th) {
	return ((a1 * a1) + (a2_m * a2_m)) * sqrt(0.5);
}
a2_m = abs(a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
real(8) function code(a1, a2_m, th)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2_m
    real(8), intent (in) :: th
    code = ((a1 * a1) + (a2_m * a2_m)) * sqrt(0.5d0)
end function
a2_m = Math.abs(a2);
assert a1 < a2_m && a2_m < th;
public static double code(double a1, double a2_m, double th) {
	return ((a1 * a1) + (a2_m * a2_m)) * Math.sqrt(0.5);
}
a2_m = math.fabs(a2)
[a1, a2_m, th] = sort([a1, a2_m, th])
def code(a1, a2_m, th):
	return ((a1 * a1) + (a2_m * a2_m)) * math.sqrt(0.5)
a2_m = abs(a2)
a1, a2_m, th = sort([a1, a2_m, th])
function code(a1, a2_m, th)
	return Float64(Float64(Float64(a1 * a1) + Float64(a2_m * a2_m)) * sqrt(0.5))
end
a2_m = abs(a2);
a1, a2_m, th = num2cell(sort([a1, a2_m, th])){:}
function tmp = code(a1, a2_m, th)
	tmp = ((a1 * a1) + (a2_m * a2_m)) * sqrt(0.5);
end
a2_m = N[Abs[a2], $MachinePrecision]
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
code[a1_, a2$95$m_, th_] := N[(N[(N[(a1 * a1), $MachinePrecision] + N[(a2$95$m * a2$95$m), $MachinePrecision]), $MachinePrecision] * N[Sqrt[0.5], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
a2_m = \left|a2\right|
\\
[a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\
\\
\left(a1 \cdot a1 + a2_m \cdot a2_m\right) \cdot \sqrt{0.5}
\end{array}
Derivation
  1. Initial program 99.5%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Step-by-step derivation
    1. distribute-lft-out99.5%

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  3. Simplified99.5%

    \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  4. Taylor expanded in th around 0 67.0%

    \[\leadsto \color{blue}{\frac{1}{\sqrt{2}}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
  5. Step-by-step derivation
    1. expm1-log1p-u67.0%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\frac{1}{\sqrt{2}}\right)\right)} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    2. expm1-udef67.0%

      \[\leadsto \color{blue}{\left(e^{\mathsf{log1p}\left(\frac{1}{\sqrt{2}}\right)} - 1\right)} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    3. add-sqr-sqrt67.0%

      \[\leadsto \left(e^{\mathsf{log1p}\left(\color{blue}{\sqrt{\frac{1}{\sqrt{2}}} \cdot \sqrt{\frac{1}{\sqrt{2}}}}\right)} - 1\right) \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    4. sqrt-unprod67.0%

      \[\leadsto \left(e^{\mathsf{log1p}\left(\color{blue}{\sqrt{\frac{1}{\sqrt{2}} \cdot \frac{1}{\sqrt{2}}}}\right)} - 1\right) \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    5. frac-times67.0%

      \[\leadsto \left(e^{\mathsf{log1p}\left(\sqrt{\color{blue}{\frac{1 \cdot 1}{\sqrt{2} \cdot \sqrt{2}}}}\right)} - 1\right) \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    6. metadata-eval67.0%

      \[\leadsto \left(e^{\mathsf{log1p}\left(\sqrt{\frac{\color{blue}{1}}{\sqrt{2} \cdot \sqrt{2}}}\right)} - 1\right) \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    7. rem-square-sqrt66.7%

      \[\leadsto \left(e^{\mathsf{log1p}\left(\sqrt{\frac{1}{\color{blue}{2}}}\right)} - 1\right) \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    8. metadata-eval66.7%

      \[\leadsto \left(e^{\mathsf{log1p}\left(\sqrt{\color{blue}{0.5}}\right)} - 1\right) \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
  6. Applied egg-rr66.7%

    \[\leadsto \color{blue}{\left(e^{\mathsf{log1p}\left(\sqrt{0.5}\right)} - 1\right)} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
  7. Step-by-step derivation
    1. expm1-def66.7%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\sqrt{0.5}\right)\right)} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    2. expm1-log1p67.1%

      \[\leadsto \color{blue}{\sqrt{0.5}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
  8. Simplified67.1%

    \[\leadsto \color{blue}{\sqrt{0.5}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
  9. Final simplification67.1%

    \[\leadsto \left(a1 \cdot a1 + a2 \cdot a2\right) \cdot \sqrt{0.5} \]

Alternative 8: 52.7% accurate, 3.9× speedup?

\[\begin{array}{l} a2_m = \left|a2\right| \\ [a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\ \\ \frac{a2_m \cdot \sqrt{0.5}}{\frac{1}{a2_m}} \end{array} \]
a2_m = (fabs.f64 a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
(FPCore (a1 a2_m th) :precision binary64 (/ (* a2_m (sqrt 0.5)) (/ 1.0 a2_m)))
a2_m = fabs(a2);
assert(a1 < a2_m && a2_m < th);
double code(double a1, double a2_m, double th) {
	return (a2_m * sqrt(0.5)) / (1.0 / a2_m);
}
a2_m = abs(a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
real(8) function code(a1, a2_m, th)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2_m
    real(8), intent (in) :: th
    code = (a2_m * sqrt(0.5d0)) / (1.0d0 / a2_m)
end function
a2_m = Math.abs(a2);
assert a1 < a2_m && a2_m < th;
public static double code(double a1, double a2_m, double th) {
	return (a2_m * Math.sqrt(0.5)) / (1.0 / a2_m);
}
a2_m = math.fabs(a2)
[a1, a2_m, th] = sort([a1, a2_m, th])
def code(a1, a2_m, th):
	return (a2_m * math.sqrt(0.5)) / (1.0 / a2_m)
a2_m = abs(a2)
a1, a2_m, th = sort([a1, a2_m, th])
function code(a1, a2_m, th)
	return Float64(Float64(a2_m * sqrt(0.5)) / Float64(1.0 / a2_m))
end
a2_m = abs(a2);
a1, a2_m, th = num2cell(sort([a1, a2_m, th])){:}
function tmp = code(a1, a2_m, th)
	tmp = (a2_m * sqrt(0.5)) / (1.0 / a2_m);
end
a2_m = N[Abs[a2], $MachinePrecision]
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
code[a1_, a2$95$m_, th_] := N[(N[(a2$95$m * N[Sqrt[0.5], $MachinePrecision]), $MachinePrecision] / N[(1.0 / a2$95$m), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
a2_m = \left|a2\right|
\\
[a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\
\\
\frac{a2_m \cdot \sqrt{0.5}}{\frac{1}{a2_m}}
\end{array}
Derivation
  1. Initial program 99.5%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Step-by-step derivation
    1. distribute-lft-out99.5%

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  3. Simplified99.5%

    \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  4. Taylor expanded in a1 around 0 57.1%

    \[\leadsto \color{blue}{\frac{{a2}^{2} \cdot \cos th}{\sqrt{2}}} \]
  5. Step-by-step derivation
    1. pow257.1%

      \[\leadsto \frac{\color{blue}{\left(a2 \cdot a2\right)} \cdot \cos th}{\sqrt{2}} \]
    2. associate-/l*57.1%

      \[\leadsto \color{blue}{\frac{a2 \cdot a2}{\frac{\sqrt{2}}{\cos th}}} \]
    3. associate-*l/57.1%

      \[\leadsto \color{blue}{\frac{a2}{\frac{\sqrt{2}}{\cos th}} \cdot a2} \]
    4. associate-/r/57.1%

      \[\leadsto \color{blue}{\left(\frac{a2}{\sqrt{2}} \cdot \cos th\right)} \cdot a2 \]
    5. associate-*l*57.1%

      \[\leadsto \color{blue}{\frac{a2}{\sqrt{2}} \cdot \left(\cos th \cdot a2\right)} \]
    6. div-inv57.0%

      \[\leadsto \color{blue}{\left(a2 \cdot \frac{1}{\sqrt{2}}\right)} \cdot \left(\cos th \cdot a2\right) \]
    7. add-sqr-sqrt57.0%

      \[\leadsto \left(a2 \cdot \color{blue}{\left(\sqrt{\frac{1}{\sqrt{2}}} \cdot \sqrt{\frac{1}{\sqrt{2}}}\right)}\right) \cdot \left(\cos th \cdot a2\right) \]
    8. sqrt-unprod57.0%

      \[\leadsto \left(a2 \cdot \color{blue}{\sqrt{\frac{1}{\sqrt{2}} \cdot \frac{1}{\sqrt{2}}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    9. frac-times57.0%

      \[\leadsto \left(a2 \cdot \sqrt{\color{blue}{\frac{1 \cdot 1}{\sqrt{2} \cdot \sqrt{2}}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    10. metadata-eval57.0%

      \[\leadsto \left(a2 \cdot \sqrt{\frac{\color{blue}{1}}{\sqrt{2} \cdot \sqrt{2}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    11. rem-square-sqrt57.1%

      \[\leadsto \left(a2 \cdot \sqrt{\frac{1}{\color{blue}{2}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    12. metadata-eval57.1%

      \[\leadsto \left(a2 \cdot \sqrt{\color{blue}{0.5}}\right) \cdot \left(\cos th \cdot a2\right) \]
  6. Applied egg-rr57.1%

    \[\leadsto \color{blue}{\left(a2 \cdot \sqrt{0.5}\right) \cdot \left(\cos th \cdot a2\right)} \]
  7. Step-by-step derivation
    1. *-commutative57.1%

      \[\leadsto \left(a2 \cdot \sqrt{0.5}\right) \cdot \color{blue}{\left(a2 \cdot \cos th\right)} \]
    2. /-rgt-identity57.1%

      \[\leadsto \left(a2 \cdot \sqrt{0.5}\right) \cdot \left(\color{blue}{\frac{a2}{1}} \cdot \cos th\right) \]
    3. associate-/r/57.0%

      \[\leadsto \left(a2 \cdot \sqrt{0.5}\right) \cdot \color{blue}{\frac{a2}{\frac{1}{\cos th}}} \]
    4. clear-num57.0%

      \[\leadsto \left(a2 \cdot \sqrt{0.5}\right) \cdot \color{blue}{\frac{1}{\frac{\frac{1}{\cos th}}{a2}}} \]
    5. un-div-inv57.0%

      \[\leadsto \color{blue}{\frac{a2 \cdot \sqrt{0.5}}{\frac{\frac{1}{\cos th}}{a2}}} \]
    6. associate-/l/57.0%

      \[\leadsto \frac{a2 \cdot \sqrt{0.5}}{\color{blue}{\frac{1}{a2 \cdot \cos th}}} \]
    7. *-commutative57.0%

      \[\leadsto \frac{a2 \cdot \sqrt{0.5}}{\frac{1}{\color{blue}{\cos th \cdot a2}}} \]
  8. Applied egg-rr57.0%

    \[\leadsto \color{blue}{\frac{a2 \cdot \sqrt{0.5}}{\frac{1}{\cos th \cdot a2}}} \]
  9. Taylor expanded in th around 0 40.9%

    \[\leadsto \frac{a2 \cdot \sqrt{0.5}}{\color{blue}{\frac{1}{a2}}} \]
  10. Final simplification40.9%

    \[\leadsto \frac{a2 \cdot \sqrt{0.5}}{\frac{1}{a2}} \]

Alternative 9: 52.7% accurate, 4.0× speedup?

\[\begin{array}{l} a2_m = \left|a2\right| \\ [a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\ \\ a2_m \cdot \left(a2_m \cdot \sqrt{0.5}\right) \end{array} \]
a2_m = (fabs.f64 a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
(FPCore (a1 a2_m th) :precision binary64 (* a2_m (* a2_m (sqrt 0.5))))
a2_m = fabs(a2);
assert(a1 < a2_m && a2_m < th);
double code(double a1, double a2_m, double th) {
	return a2_m * (a2_m * sqrt(0.5));
}
a2_m = abs(a2)
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
real(8) function code(a1, a2_m, th)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2_m
    real(8), intent (in) :: th
    code = a2_m * (a2_m * sqrt(0.5d0))
end function
a2_m = Math.abs(a2);
assert a1 < a2_m && a2_m < th;
public static double code(double a1, double a2_m, double th) {
	return a2_m * (a2_m * Math.sqrt(0.5));
}
a2_m = math.fabs(a2)
[a1, a2_m, th] = sort([a1, a2_m, th])
def code(a1, a2_m, th):
	return a2_m * (a2_m * math.sqrt(0.5))
a2_m = abs(a2)
a1, a2_m, th = sort([a1, a2_m, th])
function code(a1, a2_m, th)
	return Float64(a2_m * Float64(a2_m * sqrt(0.5)))
end
a2_m = abs(a2);
a1, a2_m, th = num2cell(sort([a1, a2_m, th])){:}
function tmp = code(a1, a2_m, th)
	tmp = a2_m * (a2_m * sqrt(0.5));
end
a2_m = N[Abs[a2], $MachinePrecision]
NOTE: a1, a2_m, and th should be sorted in increasing order before calling this function.
code[a1_, a2$95$m_, th_] := N[(a2$95$m * N[(a2$95$m * N[Sqrt[0.5], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
a2_m = \left|a2\right|
\\
[a1, a2_m, th] = \mathsf{sort}([a1, a2_m, th])\\
\\
a2_m \cdot \left(a2_m \cdot \sqrt{0.5}\right)
\end{array}
Derivation
  1. Initial program 99.5%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Step-by-step derivation
    1. distribute-lft-out99.5%

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  3. Simplified99.5%

    \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
  4. Taylor expanded in a1 around 0 57.1%

    \[\leadsto \color{blue}{\frac{{a2}^{2} \cdot \cos th}{\sqrt{2}}} \]
  5. Step-by-step derivation
    1. pow257.1%

      \[\leadsto \frac{\color{blue}{\left(a2 \cdot a2\right)} \cdot \cos th}{\sqrt{2}} \]
    2. associate-/l*57.1%

      \[\leadsto \color{blue}{\frac{a2 \cdot a2}{\frac{\sqrt{2}}{\cos th}}} \]
    3. associate-*l/57.1%

      \[\leadsto \color{blue}{\frac{a2}{\frac{\sqrt{2}}{\cos th}} \cdot a2} \]
    4. associate-/r/57.1%

      \[\leadsto \color{blue}{\left(\frac{a2}{\sqrt{2}} \cdot \cos th\right)} \cdot a2 \]
    5. associate-*l*57.1%

      \[\leadsto \color{blue}{\frac{a2}{\sqrt{2}} \cdot \left(\cos th \cdot a2\right)} \]
    6. div-inv57.0%

      \[\leadsto \color{blue}{\left(a2 \cdot \frac{1}{\sqrt{2}}\right)} \cdot \left(\cos th \cdot a2\right) \]
    7. add-sqr-sqrt57.0%

      \[\leadsto \left(a2 \cdot \color{blue}{\left(\sqrt{\frac{1}{\sqrt{2}}} \cdot \sqrt{\frac{1}{\sqrt{2}}}\right)}\right) \cdot \left(\cos th \cdot a2\right) \]
    8. sqrt-unprod57.0%

      \[\leadsto \left(a2 \cdot \color{blue}{\sqrt{\frac{1}{\sqrt{2}} \cdot \frac{1}{\sqrt{2}}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    9. frac-times57.0%

      \[\leadsto \left(a2 \cdot \sqrt{\color{blue}{\frac{1 \cdot 1}{\sqrt{2} \cdot \sqrt{2}}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    10. metadata-eval57.0%

      \[\leadsto \left(a2 \cdot \sqrt{\frac{\color{blue}{1}}{\sqrt{2} \cdot \sqrt{2}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    11. rem-square-sqrt57.1%

      \[\leadsto \left(a2 \cdot \sqrt{\frac{1}{\color{blue}{2}}}\right) \cdot \left(\cos th \cdot a2\right) \]
    12. metadata-eval57.1%

      \[\leadsto \left(a2 \cdot \sqrt{\color{blue}{0.5}}\right) \cdot \left(\cos th \cdot a2\right) \]
  6. Applied egg-rr57.1%

    \[\leadsto \color{blue}{\left(a2 \cdot \sqrt{0.5}\right) \cdot \left(\cos th \cdot a2\right)} \]
  7. Taylor expanded in th around 0 40.9%

    \[\leadsto \left(a2 \cdot \sqrt{0.5}\right) \cdot \color{blue}{a2} \]
  8. Final simplification40.9%

    \[\leadsto a2 \cdot \left(a2 \cdot \sqrt{0.5}\right) \]

Reproduce

?
herbie shell --seed 2023322 
(FPCore (a1 a2 th)
  :name "Migdal et al, Equation (64)"
  :precision binary64
  (+ (* (/ (cos th) (sqrt 2.0)) (* a1 a1)) (* (/ (cos th) (sqrt 2.0)) (* a2 a2))))