expq3 (problem 3.4.2)

Percentage Accurate: 0.0% → 99.9%
Time: 25.4s
Alternatives: 3
Speedup: 107.0×

Specification

?
\[\left(\left|a\right| \leq 710 \land \left|b\right| \leq 710\right) \land \left(10^{-27} \cdot \mathsf{min}\left(\left|a\right|, \left|b\right|\right) \leq \varepsilon \land \varepsilon \leq \mathsf{min}\left(\left|a\right|, \left|b\right|\right)\right)\]
\[\begin{array}{l} \\ \frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)} \end{array} \]
(FPCore (a b eps)
 :precision binary64
 (/
  (* eps (- (exp (* (+ a b) eps)) 1.0))
  (* (- (exp (* a eps)) 1.0) (- (exp (* b eps)) 1.0))))
double code(double a, double b, double eps) {
	return (eps * (exp(((a + b) * eps)) - 1.0)) / ((exp((a * eps)) - 1.0) * (exp((b * eps)) - 1.0));
}
real(8) function code(a, b, eps)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8), intent (in) :: eps
    code = (eps * (exp(((a + b) * eps)) - 1.0d0)) / ((exp((a * eps)) - 1.0d0) * (exp((b * eps)) - 1.0d0))
end function
public static double code(double a, double b, double eps) {
	return (eps * (Math.exp(((a + b) * eps)) - 1.0)) / ((Math.exp((a * eps)) - 1.0) * (Math.exp((b * eps)) - 1.0));
}
def code(a, b, eps):
	return (eps * (math.exp(((a + b) * eps)) - 1.0)) / ((math.exp((a * eps)) - 1.0) * (math.exp((b * eps)) - 1.0))
function code(a, b, eps)
	return Float64(Float64(eps * Float64(exp(Float64(Float64(a + b) * eps)) - 1.0)) / Float64(Float64(exp(Float64(a * eps)) - 1.0) * Float64(exp(Float64(b * eps)) - 1.0)))
end
function tmp = code(a, b, eps)
	tmp = (eps * (exp(((a + b) * eps)) - 1.0)) / ((exp((a * eps)) - 1.0) * (exp((b * eps)) - 1.0));
end
code[a_, b_, eps_] := N[(N[(eps * N[(N[Exp[N[(N[(a + b), $MachinePrecision] * eps), $MachinePrecision]], $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision] / N[(N[(N[Exp[N[(a * eps), $MachinePrecision]], $MachinePrecision] - 1.0), $MachinePrecision] * N[(N[Exp[N[(b * eps), $MachinePrecision]], $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}
\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 3 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: 0.0% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)} \end{array} \]
(FPCore (a b eps)
 :precision binary64
 (/
  (* eps (- (exp (* (+ a b) eps)) 1.0))
  (* (- (exp (* a eps)) 1.0) (- (exp (* b eps)) 1.0))))
double code(double a, double b, double eps) {
	return (eps * (exp(((a + b) * eps)) - 1.0)) / ((exp((a * eps)) - 1.0) * (exp((b * eps)) - 1.0));
}
real(8) function code(a, b, eps)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8), intent (in) :: eps
    code = (eps * (exp(((a + b) * eps)) - 1.0d0)) / ((exp((a * eps)) - 1.0d0) * (exp((b * eps)) - 1.0d0))
end function
public static double code(double a, double b, double eps) {
	return (eps * (Math.exp(((a + b) * eps)) - 1.0)) / ((Math.exp((a * eps)) - 1.0) * (Math.exp((b * eps)) - 1.0));
}
def code(a, b, eps):
	return (eps * (math.exp(((a + b) * eps)) - 1.0)) / ((math.exp((a * eps)) - 1.0) * (math.exp((b * eps)) - 1.0))
function code(a, b, eps)
	return Float64(Float64(eps * Float64(exp(Float64(Float64(a + b) * eps)) - 1.0)) / Float64(Float64(exp(Float64(a * eps)) - 1.0) * Float64(exp(Float64(b * eps)) - 1.0)))
end
function tmp = code(a, b, eps)
	tmp = (eps * (exp(((a + b) * eps)) - 1.0)) / ((exp((a * eps)) - 1.0) * (exp((b * eps)) - 1.0));
end
code[a_, b_, eps_] := N[(N[(eps * N[(N[Exp[N[(N[(a + b), $MachinePrecision] * eps), $MachinePrecision]], $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision] / N[(N[(N[Exp[N[(a * eps), $MachinePrecision]], $MachinePrecision] - 1.0), $MachinePrecision] * N[(N[Exp[N[(b * eps), $MachinePrecision]], $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}
\end{array}

Alternative 1: 99.9% accurate, 45.9× speedup?

\[\begin{array}{l} \\ \frac{1}{a} + \frac{1}{b} \end{array} \]
(FPCore (a b eps) :precision binary64 (+ (/ 1.0 a) (/ 1.0 b)))
double code(double a, double b, double eps) {
	return (1.0 / a) + (1.0 / b);
}
real(8) function code(a, b, eps)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8), intent (in) :: eps
    code = (1.0d0 / a) + (1.0d0 / b)
end function
public static double code(double a, double b, double eps) {
	return (1.0 / a) + (1.0 / b);
}
def code(a, b, eps):
	return (1.0 / a) + (1.0 / b)
function code(a, b, eps)
	return Float64(Float64(1.0 / a) + Float64(1.0 / b))
end
function tmp = code(a, b, eps)
	tmp = (1.0 / a) + (1.0 / b);
end
code[a_, b_, eps_] := N[(N[(1.0 / a), $MachinePrecision] + N[(1.0 / b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{1}{a} + \frac{1}{b}
\end{array}
Derivation
  1. Initial program 0.0%

    \[\frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)} \]
  2. Step-by-step derivation
    1. *-commutativeN/A

      \[\leadsto \frac{\left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right) \cdot \varepsilon}{\color{blue}{\left(e^{a \cdot \varepsilon} - 1\right)} \cdot \left(e^{b \cdot \varepsilon} - 1\right)} \]
    2. associate-/l*N/A

      \[\leadsto \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right) \cdot \color{blue}{\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}} \]
    3. *-lowering-*.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right), \color{blue}{\left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)}\right) \]
    4. accelerator-lowering-expm1.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\left(\left(a + b\right) \cdot \varepsilon\right)\right), \left(\frac{\color{blue}{\varepsilon}}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
    5. *-commutativeN/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\left(\varepsilon \cdot \left(a + b\right)\right)\right), \left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
    6. *-lowering-*.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \left(a + b\right)\right)\right), \left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
    7. +-lowering-+.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
    8. associate-/r*N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \left(\frac{\frac{\varepsilon}{e^{a \cdot \varepsilon} - 1}}{\color{blue}{e^{b \cdot \varepsilon} - 1}}\right)\right) \]
    9. /-lowering-/.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\left(\frac{\varepsilon}{e^{a \cdot \varepsilon} - 1}\right), \color{blue}{\left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
    10. /-lowering-/.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \left(e^{a \cdot \varepsilon} - 1\right)\right), \left(\color{blue}{e^{b \cdot \varepsilon}} - 1\right)\right)\right) \]
    11. accelerator-lowering-expm1.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\left(a \cdot \varepsilon\right)\right)\right), \left(e^{b \cdot \varepsilon} - 1\right)\right)\right) \]
    12. *-commutativeN/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\left(\varepsilon \cdot a\right)\right)\right), \left(e^{b \cdot \varepsilon} - 1\right)\right)\right) \]
    13. *-lowering-*.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \left(e^{b \cdot \varepsilon} - 1\right)\right)\right) \]
    14. accelerator-lowering-expm1.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \mathsf{expm1.f64}\left(\left(b \cdot \varepsilon\right)\right)\right)\right) \]
    15. *-commutativeN/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \mathsf{expm1.f64}\left(\left(\varepsilon \cdot b\right)\right)\right)\right) \]
    16. *-lowering-*.f6419.9%

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, b\right)\right)\right)\right) \]
  3. Simplified19.9%

    \[\leadsto \color{blue}{\mathsf{expm1}\left(\varepsilon \cdot \left(a + b\right)\right) \cdot \frac{\frac{\varepsilon}{\mathsf{expm1}\left(\varepsilon \cdot a\right)}}{\mathsf{expm1}\left(\varepsilon \cdot b\right)}} \]
  4. Add Preprocessing
  5. Taylor expanded in eps around 0

    \[\leadsto \color{blue}{\frac{a + b}{a \cdot b}} \]
  6. Step-by-step derivation
    1. associate-/r*N/A

      \[\leadsto \frac{\frac{a + b}{a}}{\color{blue}{b}} \]
    2. /-lowering-/.f64N/A

      \[\leadsto \mathsf{/.f64}\left(\left(\frac{a + b}{a}\right), \color{blue}{b}\right) \]
    3. /-lowering-/.f64N/A

      \[\leadsto \mathsf{/.f64}\left(\mathsf{/.f64}\left(\left(a + b\right), a\right), b\right) \]
    4. +-lowering-+.f6499.8%

      \[\leadsto \mathsf{/.f64}\left(\mathsf{/.f64}\left(\mathsf{+.f64}\left(a, b\right), a\right), b\right) \]
  7. Simplified99.8%

    \[\leadsto \color{blue}{\frac{\frac{a + b}{a}}{b}} \]
  8. Taylor expanded in a around inf

    \[\leadsto \color{blue}{\frac{1}{a} + \frac{1}{b}} \]
  9. Step-by-step derivation
    1. +-lowering-+.f64N/A

      \[\leadsto \mathsf{+.f64}\left(\left(\frac{1}{a}\right), \color{blue}{\left(\frac{1}{b}\right)}\right) \]
    2. /-lowering-/.f64N/A

      \[\leadsto \mathsf{+.f64}\left(\mathsf{/.f64}\left(1, a\right), \left(\frac{\color{blue}{1}}{b}\right)\right) \]
    3. /-lowering-/.f64100.0%

      \[\leadsto \mathsf{+.f64}\left(\mathsf{/.f64}\left(1, a\right), \mathsf{/.f64}\left(1, \color{blue}{b}\right)\right) \]
  10. Simplified100.0%

    \[\leadsto \color{blue}{\frac{1}{a} + \frac{1}{b}} \]
  11. Add Preprocessing

Alternative 2: 60.1% accurate, 40.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;a \leq -1.65 \cdot 10^{-191}:\\ \;\;\;\;\frac{1}{b}\\ \mathbf{else}:\\ \;\;\;\;\frac{1}{a}\\ \end{array} \end{array} \]
(FPCore (a b eps)
 :precision binary64
 (if (<= a -1.65e-191) (/ 1.0 b) (/ 1.0 a)))
double code(double a, double b, double eps) {
	double tmp;
	if (a <= -1.65e-191) {
		tmp = 1.0 / b;
	} else {
		tmp = 1.0 / a;
	}
	return tmp;
}
real(8) function code(a, b, eps)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8), intent (in) :: eps
    real(8) :: tmp
    if (a <= (-1.65d-191)) then
        tmp = 1.0d0 / b
    else
        tmp = 1.0d0 / a
    end if
    code = tmp
end function
public static double code(double a, double b, double eps) {
	double tmp;
	if (a <= -1.65e-191) {
		tmp = 1.0 / b;
	} else {
		tmp = 1.0 / a;
	}
	return tmp;
}
def code(a, b, eps):
	tmp = 0
	if a <= -1.65e-191:
		tmp = 1.0 / b
	else:
		tmp = 1.0 / a
	return tmp
function code(a, b, eps)
	tmp = 0.0
	if (a <= -1.65e-191)
		tmp = Float64(1.0 / b);
	else
		tmp = Float64(1.0 / a);
	end
	return tmp
end
function tmp_2 = code(a, b, eps)
	tmp = 0.0;
	if (a <= -1.65e-191)
		tmp = 1.0 / b;
	else
		tmp = 1.0 / a;
	end
	tmp_2 = tmp;
end
code[a_, b_, eps_] := If[LessEqual[a, -1.65e-191], N[(1.0 / b), $MachinePrecision], N[(1.0 / a), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;a \leq -1.65 \cdot 10^{-191}:\\
\;\;\;\;\frac{1}{b}\\

\mathbf{else}:\\
\;\;\;\;\frac{1}{a}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if a < -1.64999999999999991e-191

    1. Initial program 0.0%

      \[\frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)} \]
    2. Step-by-step derivation
      1. *-commutativeN/A

        \[\leadsto \frac{\left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right) \cdot \varepsilon}{\color{blue}{\left(e^{a \cdot \varepsilon} - 1\right)} \cdot \left(e^{b \cdot \varepsilon} - 1\right)} \]
      2. associate-/l*N/A

        \[\leadsto \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right) \cdot \color{blue}{\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}} \]
      3. *-lowering-*.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right), \color{blue}{\left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)}\right) \]
      4. accelerator-lowering-expm1.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\left(\left(a + b\right) \cdot \varepsilon\right)\right), \left(\frac{\color{blue}{\varepsilon}}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
      5. *-commutativeN/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\left(\varepsilon \cdot \left(a + b\right)\right)\right), \left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
      6. *-lowering-*.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \left(a + b\right)\right)\right), \left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
      7. +-lowering-+.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
      8. associate-/r*N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \left(\frac{\frac{\varepsilon}{e^{a \cdot \varepsilon} - 1}}{\color{blue}{e^{b \cdot \varepsilon} - 1}}\right)\right) \]
      9. /-lowering-/.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\left(\frac{\varepsilon}{e^{a \cdot \varepsilon} - 1}\right), \color{blue}{\left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
      10. /-lowering-/.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \left(e^{a \cdot \varepsilon} - 1\right)\right), \left(\color{blue}{e^{b \cdot \varepsilon}} - 1\right)\right)\right) \]
      11. accelerator-lowering-expm1.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\left(a \cdot \varepsilon\right)\right)\right), \left(e^{b \cdot \varepsilon} - 1\right)\right)\right) \]
      12. *-commutativeN/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\left(\varepsilon \cdot a\right)\right)\right), \left(e^{b \cdot \varepsilon} - 1\right)\right)\right) \]
      13. *-lowering-*.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \left(e^{b \cdot \varepsilon} - 1\right)\right)\right) \]
      14. accelerator-lowering-expm1.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \mathsf{expm1.f64}\left(\left(b \cdot \varepsilon\right)\right)\right)\right) \]
      15. *-commutativeN/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \mathsf{expm1.f64}\left(\left(\varepsilon \cdot b\right)\right)\right)\right) \]
      16. *-lowering-*.f6431.1%

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, b\right)\right)\right)\right) \]
    3. Simplified31.1%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\varepsilon \cdot \left(a + b\right)\right) \cdot \frac{\frac{\varepsilon}{\mathsf{expm1}\left(\varepsilon \cdot a\right)}}{\mathsf{expm1}\left(\varepsilon \cdot b\right)}} \]
    4. Add Preprocessing
    5. Taylor expanded in b around 0

      \[\leadsto \color{blue}{\frac{1}{b}} \]
    6. Step-by-step derivation
      1. /-lowering-/.f6468.6%

        \[\leadsto \mathsf{/.f64}\left(1, \color{blue}{b}\right) \]
    7. Simplified68.6%

      \[\leadsto \color{blue}{\frac{1}{b}} \]

    if -1.64999999999999991e-191 < a

    1. Initial program 0.0%

      \[\frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)} \]
    2. Step-by-step derivation
      1. *-commutativeN/A

        \[\leadsto \frac{\left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right) \cdot \varepsilon}{\color{blue}{\left(e^{a \cdot \varepsilon} - 1\right)} \cdot \left(e^{b \cdot \varepsilon} - 1\right)} \]
      2. associate-/l*N/A

        \[\leadsto \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right) \cdot \color{blue}{\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}} \]
      3. *-lowering-*.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right), \color{blue}{\left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)}\right) \]
      4. accelerator-lowering-expm1.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\left(\left(a + b\right) \cdot \varepsilon\right)\right), \left(\frac{\color{blue}{\varepsilon}}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
      5. *-commutativeN/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\left(\varepsilon \cdot \left(a + b\right)\right)\right), \left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
      6. *-lowering-*.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \left(a + b\right)\right)\right), \left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
      7. +-lowering-+.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
      8. associate-/r*N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \left(\frac{\frac{\varepsilon}{e^{a \cdot \varepsilon} - 1}}{\color{blue}{e^{b \cdot \varepsilon} - 1}}\right)\right) \]
      9. /-lowering-/.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\left(\frac{\varepsilon}{e^{a \cdot \varepsilon} - 1}\right), \color{blue}{\left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
      10. /-lowering-/.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \left(e^{a \cdot \varepsilon} - 1\right)\right), \left(\color{blue}{e^{b \cdot \varepsilon}} - 1\right)\right)\right) \]
      11. accelerator-lowering-expm1.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\left(a \cdot \varepsilon\right)\right)\right), \left(e^{b \cdot \varepsilon} - 1\right)\right)\right) \]
      12. *-commutativeN/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\left(\varepsilon \cdot a\right)\right)\right), \left(e^{b \cdot \varepsilon} - 1\right)\right)\right) \]
      13. *-lowering-*.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \left(e^{b \cdot \varepsilon} - 1\right)\right)\right) \]
      14. accelerator-lowering-expm1.f64N/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \mathsf{expm1.f64}\left(\left(b \cdot \varepsilon\right)\right)\right)\right) \]
      15. *-commutativeN/A

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \mathsf{expm1.f64}\left(\left(\varepsilon \cdot b\right)\right)\right)\right) \]
      16. *-lowering-*.f6413.2%

        \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, b\right)\right)\right)\right) \]
    3. Simplified13.2%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\varepsilon \cdot \left(a + b\right)\right) \cdot \frac{\frac{\varepsilon}{\mathsf{expm1}\left(\varepsilon \cdot a\right)}}{\mathsf{expm1}\left(\varepsilon \cdot b\right)}} \]
    4. Add Preprocessing
    5. Taylor expanded in a around 0

      \[\leadsto \color{blue}{\frac{1}{a}} \]
    6. Step-by-step derivation
      1. /-lowering-/.f6459.3%

        \[\leadsto \mathsf{/.f64}\left(1, \color{blue}{a}\right) \]
    7. Simplified59.3%

      \[\leadsto \color{blue}{\frac{1}{a}} \]
  3. Recombined 2 regimes into one program.
  4. Add Preprocessing

Alternative 3: 49.7% accurate, 107.0× speedup?

\[\begin{array}{l} \\ \frac{1}{a} \end{array} \]
(FPCore (a b eps) :precision binary64 (/ 1.0 a))
double code(double a, double b, double eps) {
	return 1.0 / a;
}
real(8) function code(a, b, eps)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8), intent (in) :: eps
    code = 1.0d0 / a
end function
public static double code(double a, double b, double eps) {
	return 1.0 / a;
}
def code(a, b, eps):
	return 1.0 / a
function code(a, b, eps)
	return Float64(1.0 / a)
end
function tmp = code(a, b, eps)
	tmp = 1.0 / a;
end
code[a_, b_, eps_] := N[(1.0 / a), $MachinePrecision]
\begin{array}{l}

\\
\frac{1}{a}
\end{array}
Derivation
  1. Initial program 0.0%

    \[\frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)} \]
  2. Step-by-step derivation
    1. *-commutativeN/A

      \[\leadsto \frac{\left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right) \cdot \varepsilon}{\color{blue}{\left(e^{a \cdot \varepsilon} - 1\right)} \cdot \left(e^{b \cdot \varepsilon} - 1\right)} \]
    2. associate-/l*N/A

      \[\leadsto \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right) \cdot \color{blue}{\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}} \]
    3. *-lowering-*.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right), \color{blue}{\left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)}\right) \]
    4. accelerator-lowering-expm1.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\left(\left(a + b\right) \cdot \varepsilon\right)\right), \left(\frac{\color{blue}{\varepsilon}}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
    5. *-commutativeN/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\left(\varepsilon \cdot \left(a + b\right)\right)\right), \left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
    6. *-lowering-*.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \left(a + b\right)\right)\right), \left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
    7. +-lowering-+.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \left(\frac{\varepsilon}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
    8. associate-/r*N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \left(\frac{\frac{\varepsilon}{e^{a \cdot \varepsilon} - 1}}{\color{blue}{e^{b \cdot \varepsilon} - 1}}\right)\right) \]
    9. /-lowering-/.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\left(\frac{\varepsilon}{e^{a \cdot \varepsilon} - 1}\right), \color{blue}{\left(e^{b \cdot \varepsilon} - 1\right)}\right)\right) \]
    10. /-lowering-/.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \left(e^{a \cdot \varepsilon} - 1\right)\right), \left(\color{blue}{e^{b \cdot \varepsilon}} - 1\right)\right)\right) \]
    11. accelerator-lowering-expm1.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\left(a \cdot \varepsilon\right)\right)\right), \left(e^{b \cdot \varepsilon} - 1\right)\right)\right) \]
    12. *-commutativeN/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\left(\varepsilon \cdot a\right)\right)\right), \left(e^{b \cdot \varepsilon} - 1\right)\right)\right) \]
    13. *-lowering-*.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \left(e^{b \cdot \varepsilon} - 1\right)\right)\right) \]
    14. accelerator-lowering-expm1.f64N/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \mathsf{expm1.f64}\left(\left(b \cdot \varepsilon\right)\right)\right)\right) \]
    15. *-commutativeN/A

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \mathsf{expm1.f64}\left(\left(\varepsilon \cdot b\right)\right)\right)\right) \]
    16. *-lowering-*.f6419.9%

      \[\leadsto \mathsf{*.f64}\left(\mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, \mathsf{+.f64}\left(a, b\right)\right)\right), \mathsf{/.f64}\left(\mathsf{/.f64}\left(\varepsilon, \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, a\right)\right)\right), \mathsf{expm1.f64}\left(\mathsf{*.f64}\left(\varepsilon, b\right)\right)\right)\right) \]
  3. Simplified19.9%

    \[\leadsto \color{blue}{\mathsf{expm1}\left(\varepsilon \cdot \left(a + b\right)\right) \cdot \frac{\frac{\varepsilon}{\mathsf{expm1}\left(\varepsilon \cdot a\right)}}{\mathsf{expm1}\left(\varepsilon \cdot b\right)}} \]
  4. Add Preprocessing
  5. Taylor expanded in a around 0

    \[\leadsto \color{blue}{\frac{1}{a}} \]
  6. Step-by-step derivation
    1. /-lowering-/.f6449.0%

      \[\leadsto \mathsf{/.f64}\left(1, \color{blue}{a}\right) \]
  7. Simplified49.0%

    \[\leadsto \color{blue}{\frac{1}{a}} \]
  8. Add Preprocessing

Developer Target 1: 99.9% accurate, 45.9× speedup?

\[\begin{array}{l} \\ \frac{1}{a} + \frac{1}{b} \end{array} \]
(FPCore (a b eps) :precision binary64 (+ (/ 1.0 a) (/ 1.0 b)))
double code(double a, double b, double eps) {
	return (1.0 / a) + (1.0 / b);
}
real(8) function code(a, b, eps)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8), intent (in) :: eps
    code = (1.0d0 / a) + (1.0d0 / b)
end function
public static double code(double a, double b, double eps) {
	return (1.0 / a) + (1.0 / b);
}
def code(a, b, eps):
	return (1.0 / a) + (1.0 / b)
function code(a, b, eps)
	return Float64(Float64(1.0 / a) + Float64(1.0 / b))
end
function tmp = code(a, b, eps)
	tmp = (1.0 / a) + (1.0 / b);
end
code[a_, b_, eps_] := N[(N[(1.0 / a), $MachinePrecision] + N[(1.0 / b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{1}{a} + \frac{1}{b}
\end{array}

Reproduce

?
herbie shell --seed 2024191 
(FPCore (a b eps)
  :name "expq3 (problem 3.4.2)"
  :precision binary64
  :pre (and (and (<= (fabs a) 710.0) (<= (fabs b) 710.0)) (and (<= (* 1e-27 (fmin (fabs a) (fabs b))) eps) (<= eps (fmin (fabs a) (fabs b)))))

  :alt
  (! :herbie-platform default (+ (/ 1 a) (/ 1 b)))

  (/ (* eps (- (exp (* (+ a b) eps)) 1.0)) (* (- (exp (* a eps)) 1.0) (- (exp (* b eps)) 1.0))))