NMSE Section 6.1 mentioned, B

Percentage Accurate: 78.6% → 99.6%
Time: 14.5s
Alternatives: 4
Speedup: 1.9×

Specification

?
\[\begin{array}{l} \\ \left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \end{array} \]
(FPCore (a b)
 :precision binary64
 (* (* (/ PI 2.0) (/ 1.0 (- (* b b) (* a a)))) (- (/ 1.0 a) (/ 1.0 b))))
double code(double a, double b) {
	return ((((double) M_PI) / 2.0) * (1.0 / ((b * b) - (a * a)))) * ((1.0 / a) - (1.0 / b));
}
public static double code(double a, double b) {
	return ((Math.PI / 2.0) * (1.0 / ((b * b) - (a * a)))) * ((1.0 / a) - (1.0 / b));
}
def code(a, b):
	return ((math.pi / 2.0) * (1.0 / ((b * b) - (a * a)))) * ((1.0 / a) - (1.0 / b))
function code(a, b)
	return Float64(Float64(Float64(pi / 2.0) * Float64(1.0 / Float64(Float64(b * b) - Float64(a * a)))) * Float64(Float64(1.0 / a) - Float64(1.0 / b)))
end
function tmp = code(a, b)
	tmp = ((pi / 2.0) * (1.0 / ((b * b) - (a * a)))) * ((1.0 / a) - (1.0 / b));
end
code[a_, b_] := N[(N[(N[(Pi / 2.0), $MachinePrecision] * N[(1.0 / N[(N[(b * b), $MachinePrecision] - N[(a * a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] * N[(N[(1.0 / a), $MachinePrecision] - N[(1.0 / b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\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 4 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: 78.6% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \end{array} \]
(FPCore (a b)
 :precision binary64
 (* (* (/ PI 2.0) (/ 1.0 (- (* b b) (* a a)))) (- (/ 1.0 a) (/ 1.0 b))))
double code(double a, double b) {
	return ((((double) M_PI) / 2.0) * (1.0 / ((b * b) - (a * a)))) * ((1.0 / a) - (1.0 / b));
}
public static double code(double a, double b) {
	return ((Math.PI / 2.0) * (1.0 / ((b * b) - (a * a)))) * ((1.0 / a) - (1.0 / b));
}
def code(a, b):
	return ((math.pi / 2.0) * (1.0 / ((b * b) - (a * a)))) * ((1.0 / a) - (1.0 / b))
function code(a, b)
	return Float64(Float64(Float64(pi / 2.0) * Float64(1.0 / Float64(Float64(b * b) - Float64(a * a)))) * Float64(Float64(1.0 / a) - Float64(1.0 / b)))
end
function tmp = code(a, b)
	tmp = ((pi / 2.0) * (1.0 / ((b * b) - (a * a)))) * ((1.0 / a) - (1.0 / b));
end
code[a_, b_] := N[(N[(N[(Pi / 2.0), $MachinePrecision] * N[(1.0 / N[(N[(b * b), $MachinePrecision] - N[(a * a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] * N[(N[(1.0 / a), $MachinePrecision] - N[(1.0 / b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\right)
\end{array}

Alternative 1: 99.6% accurate, 1.1× speedup?

\[\begin{array}{l} \\ \frac{\frac{\pi \cdot 0.5}{b + a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)}{b - a} \end{array} \]
(FPCore (a b)
 :precision binary64
 (/ (* (/ (* PI 0.5) (+ b a)) (- (/ 1.0 a) (/ 1.0 b))) (- b a)))
double code(double a, double b) {
	return (((((double) M_PI) * 0.5) / (b + a)) * ((1.0 / a) - (1.0 / b))) / (b - a);
}
public static double code(double a, double b) {
	return (((Math.PI * 0.5) / (b + a)) * ((1.0 / a) - (1.0 / b))) / (b - a);
}
def code(a, b):
	return (((math.pi * 0.5) / (b + a)) * ((1.0 / a) - (1.0 / b))) / (b - a)
function code(a, b)
	return Float64(Float64(Float64(Float64(pi * 0.5) / Float64(b + a)) * Float64(Float64(1.0 / a) - Float64(1.0 / b))) / Float64(b - a))
end
function tmp = code(a, b)
	tmp = (((pi * 0.5) / (b + a)) * ((1.0 / a) - (1.0 / b))) / (b - a);
end
code[a_, b_] := N[(N[(N[(N[(Pi * 0.5), $MachinePrecision] / N[(b + a), $MachinePrecision]), $MachinePrecision] * N[(N[(1.0 / a), $MachinePrecision] - N[(1.0 / b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(b - a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\frac{\pi \cdot 0.5}{b + a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)}{b - a}
\end{array}
Derivation
  1. Initial program 77.1%

    \[\left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. un-div-inv77.1%

      \[\leadsto \color{blue}{\frac{\frac{\pi}{2}}{b \cdot b - a \cdot a}} \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \]
    2. difference-of-squares86.5%

      \[\leadsto \frac{\frac{\pi}{2}}{\color{blue}{\left(b + a\right) \cdot \left(b - a\right)}} \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \]
    3. associate-/r*86.5%

      \[\leadsto \color{blue}{\frac{\frac{\frac{\pi}{2}}{b + a}}{b - a}} \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \]
    4. div-inv86.5%

      \[\leadsto \frac{\frac{\color{blue}{\pi \cdot \frac{1}{2}}}{b + a}}{b - a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \]
    5. metadata-eval86.5%

      \[\leadsto \frac{\frac{\pi \cdot \color{blue}{0.5}}{b + a}}{b - a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \]
  4. Applied egg-rr86.5%

    \[\leadsto \color{blue}{\frac{\frac{\pi \cdot 0.5}{b + a}}{b - a}} \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \]
  5. Step-by-step derivation
    1. associate-*l/99.7%

      \[\leadsto \color{blue}{\frac{\frac{\pi \cdot 0.5}{b + a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)}{b - a}} \]
  6. Applied egg-rr99.7%

    \[\leadsto \color{blue}{\frac{\frac{\pi \cdot 0.5}{b + a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)}{b - a}} \]
  7. Final simplification99.7%

    \[\leadsto \frac{\frac{\pi \cdot 0.5}{b + a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)}{b - a} \]
  8. Add Preprocessing

Alternative 2: 66.6% accurate, 1.4× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \frac{0.5}{b \cdot a}\\ \mathbf{if}\;a \leq -1.2 \cdot 10^{+109}:\\ \;\;\;\;\frac{\pi}{-a} \cdot t\_0\\ \mathbf{else}:\\ \;\;\;\;\frac{\pi}{b} \cdot t\_0\\ \end{array} \end{array} \]
(FPCore (a b)
 :precision binary64
 (let* ((t_0 (/ 0.5 (* b a))))
   (if (<= a -1.2e+109) (* (/ PI (- a)) t_0) (* (/ PI b) t_0))))
double code(double a, double b) {
	double t_0 = 0.5 / (b * a);
	double tmp;
	if (a <= -1.2e+109) {
		tmp = (((double) M_PI) / -a) * t_0;
	} else {
		tmp = (((double) M_PI) / b) * t_0;
	}
	return tmp;
}
public static double code(double a, double b) {
	double t_0 = 0.5 / (b * a);
	double tmp;
	if (a <= -1.2e+109) {
		tmp = (Math.PI / -a) * t_0;
	} else {
		tmp = (Math.PI / b) * t_0;
	}
	return tmp;
}
def code(a, b):
	t_0 = 0.5 / (b * a)
	tmp = 0
	if a <= -1.2e+109:
		tmp = (math.pi / -a) * t_0
	else:
		tmp = (math.pi / b) * t_0
	return tmp
function code(a, b)
	t_0 = Float64(0.5 / Float64(b * a))
	tmp = 0.0
	if (a <= -1.2e+109)
		tmp = Float64(Float64(pi / Float64(-a)) * t_0);
	else
		tmp = Float64(Float64(pi / b) * t_0);
	end
	return tmp
end
function tmp_2 = code(a, b)
	t_0 = 0.5 / (b * a);
	tmp = 0.0;
	if (a <= -1.2e+109)
		tmp = (pi / -a) * t_0;
	else
		tmp = (pi / b) * t_0;
	end
	tmp_2 = tmp;
end
code[a_, b_] := Block[{t$95$0 = N[(0.5 / N[(b * a), $MachinePrecision]), $MachinePrecision]}, If[LessEqual[a, -1.2e+109], N[(N[(Pi / (-a)), $MachinePrecision] * t$95$0), $MachinePrecision], N[(N[(Pi / b), $MachinePrecision] * t$95$0), $MachinePrecision]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \frac{0.5}{b \cdot a}\\
\mathbf{if}\;a \leq -1.2 \cdot 10^{+109}:\\
\;\;\;\;\frac{\pi}{-a} \cdot t\_0\\

\mathbf{else}:\\
\;\;\;\;\frac{\pi}{b} \cdot t\_0\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if a < -1.19999999999999994e109

    1. Initial program 62.6%

      \[\left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \]
    2. Step-by-step derivation
      1. associate-*l*62.5%

        \[\leadsto \color{blue}{\frac{\pi}{2} \cdot \left(\frac{1}{b \cdot b - a \cdot a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)\right)} \]
      2. *-rgt-identity62.5%

        \[\leadsto \frac{\color{blue}{\pi \cdot 1}}{2} \cdot \left(\frac{1}{b \cdot b - a \cdot a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)\right) \]
      3. associate-/l*62.5%

        \[\leadsto \color{blue}{\left(\pi \cdot \frac{1}{2}\right)} \cdot \left(\frac{1}{b \cdot b - a \cdot a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)\right) \]
      4. metadata-eval62.5%

        \[\leadsto \left(\pi \cdot \color{blue}{0.5}\right) \cdot \left(\frac{1}{b \cdot b - a \cdot a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)\right) \]
      5. associate-*l/62.6%

        \[\leadsto \left(\pi \cdot 0.5\right) \cdot \color{blue}{\frac{1 \cdot \left(\frac{1}{a} - \frac{1}{b}\right)}{b \cdot b - a \cdot a}} \]
      6. *-lft-identity62.6%

        \[\leadsto \left(\pi \cdot 0.5\right) \cdot \frac{\color{blue}{\frac{1}{a} - \frac{1}{b}}}{b \cdot b - a \cdot a} \]
      7. sub-neg62.6%

        \[\leadsto \left(\pi \cdot 0.5\right) \cdot \frac{\color{blue}{\frac{1}{a} + \left(-\frac{1}{b}\right)}}{b \cdot b - a \cdot a} \]
      8. distribute-neg-frac62.6%

        \[\leadsto \left(\pi \cdot 0.5\right) \cdot \frac{\frac{1}{a} + \color{blue}{\frac{-1}{b}}}{b \cdot b - a \cdot a} \]
      9. metadata-eval62.6%

        \[\leadsto \left(\pi \cdot 0.5\right) \cdot \frac{\frac{1}{a} + \frac{\color{blue}{-1}}{b}}{b \cdot b - a \cdot a} \]
    3. Simplified62.6%

      \[\leadsto \color{blue}{\left(\pi \cdot 0.5\right) \cdot \frac{\frac{1}{a} + \frac{-1}{b}}{b \cdot b - a \cdot a}} \]
    4. Add Preprocessing
    5. Step-by-step derivation
      1. metadata-eval62.6%

        \[\leadsto \left(\pi \cdot \color{blue}{\frac{1}{2}}\right) \cdot \frac{\frac{1}{a} + \frac{-1}{b}}{b \cdot b - a \cdot a} \]
      2. div-inv62.6%

        \[\leadsto \color{blue}{\frac{\pi}{2}} \cdot \frac{\frac{1}{a} + \frac{-1}{b}}{b \cdot b - a \cdot a} \]
      3. associate-*r/62.6%

        \[\leadsto \color{blue}{\frac{\frac{\pi}{2} \cdot \left(\frac{1}{a} + \frac{-1}{b}\right)}{b \cdot b - a \cdot a}} \]
      4. *-commutative62.6%

        \[\leadsto \frac{\color{blue}{\left(\frac{1}{a} + \frac{-1}{b}\right) \cdot \frac{\pi}{2}}}{b \cdot b - a \cdot a} \]
      5. difference-of-squares76.9%

        \[\leadsto \frac{\left(\frac{1}{a} + \frac{-1}{b}\right) \cdot \frac{\pi}{2}}{\color{blue}{\left(b + a\right) \cdot \left(b - a\right)}} \]
      6. associate-/r*99.8%

        \[\leadsto \color{blue}{\frac{\frac{\left(\frac{1}{a} + \frac{-1}{b}\right) \cdot \frac{\pi}{2}}{b + a}}{b - a}} \]
    6. Applied egg-rr68.1%

      \[\leadsto \color{blue}{\frac{\frac{\left(\frac{1}{a} + \frac{1}{b}\right) \cdot \left(\pi \cdot 0.5\right)}{b + a}}{b - a}} \]
    7. Taylor expanded in a around 0 68.1%

      \[\leadsto \frac{\color{blue}{0.5 \cdot \frac{\pi}{a \cdot b}}}{b - a} \]
    8. Step-by-step derivation
      1. associate-*r/68.1%

        \[\leadsto \frac{\color{blue}{\frac{0.5 \cdot \pi}{a \cdot b}}}{b - a} \]
    9. Simplified68.1%

      \[\leadsto \frac{\color{blue}{\frac{0.5 \cdot \pi}{a \cdot b}}}{b - a} \]
    10. Step-by-step derivation
      1. *-un-lft-identity68.1%

        \[\leadsto \color{blue}{1 \cdot \frac{\frac{0.5 \cdot \pi}{a \cdot b}}{b - a}} \]
      2. associate-/l/68.1%

        \[\leadsto 1 \cdot \color{blue}{\frac{0.5 \cdot \pi}{\left(b - a\right) \cdot \left(a \cdot b\right)}} \]
      3. *-commutative68.1%

        \[\leadsto 1 \cdot \frac{\color{blue}{\pi \cdot 0.5}}{\left(b - a\right) \cdot \left(a \cdot b\right)} \]
      4. *-commutative68.1%

        \[\leadsto 1 \cdot \frac{\pi \cdot 0.5}{\left(b - a\right) \cdot \color{blue}{\left(b \cdot a\right)}} \]
    11. Applied egg-rr68.1%

      \[\leadsto \color{blue}{1 \cdot \frac{\pi \cdot 0.5}{\left(b - a\right) \cdot \left(b \cdot a\right)}} \]
    12. Step-by-step derivation
      1. *-lft-identity68.1%

        \[\leadsto \color{blue}{\frac{\pi \cdot 0.5}{\left(b - a\right) \cdot \left(b \cdot a\right)}} \]
      2. times-frac68.1%

        \[\leadsto \color{blue}{\frac{\pi}{b - a} \cdot \frac{0.5}{b \cdot a}} \]
      3. *-commutative68.1%

        \[\leadsto \frac{\pi}{b - a} \cdot \frac{0.5}{\color{blue}{a \cdot b}} \]
    13. Simplified68.1%

      \[\leadsto \color{blue}{\frac{\pi}{b - a} \cdot \frac{0.5}{a \cdot b}} \]
    14. Taylor expanded in b around 0 68.1%

      \[\leadsto \color{blue}{\left(-1 \cdot \frac{\pi}{a}\right)} \cdot \frac{0.5}{a \cdot b} \]
    15. Step-by-step derivation
      1. neg-mul-168.1%

        \[\leadsto \color{blue}{\left(-\frac{\pi}{a}\right)} \cdot \frac{0.5}{a \cdot b} \]
      2. distribute-neg-frac268.1%

        \[\leadsto \color{blue}{\frac{\pi}{-a}} \cdot \frac{0.5}{a \cdot b} \]
    16. Simplified68.1%

      \[\leadsto \color{blue}{\frac{\pi}{-a}} \cdot \frac{0.5}{a \cdot b} \]

    if -1.19999999999999994e109 < a

    1. Initial program 80.5%

      \[\left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \]
    2. Step-by-step derivation
      1. associate-*l*80.5%

        \[\leadsto \color{blue}{\frac{\pi}{2} \cdot \left(\frac{1}{b \cdot b - a \cdot a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)\right)} \]
      2. *-rgt-identity80.5%

        \[\leadsto \frac{\color{blue}{\pi \cdot 1}}{2} \cdot \left(\frac{1}{b \cdot b - a \cdot a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)\right) \]
      3. associate-/l*80.5%

        \[\leadsto \color{blue}{\left(\pi \cdot \frac{1}{2}\right)} \cdot \left(\frac{1}{b \cdot b - a \cdot a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)\right) \]
      4. metadata-eval80.5%

        \[\leadsto \left(\pi \cdot \color{blue}{0.5}\right) \cdot \left(\frac{1}{b \cdot b - a \cdot a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)\right) \]
      5. associate-*l/80.6%

        \[\leadsto \left(\pi \cdot 0.5\right) \cdot \color{blue}{\frac{1 \cdot \left(\frac{1}{a} - \frac{1}{b}\right)}{b \cdot b - a \cdot a}} \]
      6. *-lft-identity80.6%

        \[\leadsto \left(\pi \cdot 0.5\right) \cdot \frac{\color{blue}{\frac{1}{a} - \frac{1}{b}}}{b \cdot b - a \cdot a} \]
      7. sub-neg80.6%

        \[\leadsto \left(\pi \cdot 0.5\right) \cdot \frac{\color{blue}{\frac{1}{a} + \left(-\frac{1}{b}\right)}}{b \cdot b - a \cdot a} \]
      8. distribute-neg-frac80.6%

        \[\leadsto \left(\pi \cdot 0.5\right) \cdot \frac{\frac{1}{a} + \color{blue}{\frac{-1}{b}}}{b \cdot b - a \cdot a} \]
      9. metadata-eval80.6%

        \[\leadsto \left(\pi \cdot 0.5\right) \cdot \frac{\frac{1}{a} + \frac{\color{blue}{-1}}{b}}{b \cdot b - a \cdot a} \]
    3. Simplified80.6%

      \[\leadsto \color{blue}{\left(\pi \cdot 0.5\right) \cdot \frac{\frac{1}{a} + \frac{-1}{b}}{b \cdot b - a \cdot a}} \]
    4. Add Preprocessing
    5. Step-by-step derivation
      1. metadata-eval80.6%

        \[\leadsto \left(\pi \cdot \color{blue}{\frac{1}{2}}\right) \cdot \frac{\frac{1}{a} + \frac{-1}{b}}{b \cdot b - a \cdot a} \]
      2. div-inv80.6%

        \[\leadsto \color{blue}{\frac{\pi}{2}} \cdot \frac{\frac{1}{a} + \frac{-1}{b}}{b \cdot b - a \cdot a} \]
      3. associate-*r/80.6%

        \[\leadsto \color{blue}{\frac{\frac{\pi}{2} \cdot \left(\frac{1}{a} + \frac{-1}{b}\right)}{b \cdot b - a \cdot a}} \]
      4. *-commutative80.6%

        \[\leadsto \frac{\color{blue}{\left(\frac{1}{a} + \frac{-1}{b}\right) \cdot \frac{\pi}{2}}}{b \cdot b - a \cdot a} \]
      5. difference-of-squares88.8%

        \[\leadsto \frac{\left(\frac{1}{a} + \frac{-1}{b}\right) \cdot \frac{\pi}{2}}{\color{blue}{\left(b + a\right) \cdot \left(b - a\right)}} \]
      6. associate-/r*99.6%

        \[\leadsto \color{blue}{\frac{\frac{\left(\frac{1}{a} + \frac{-1}{b}\right) \cdot \frac{\pi}{2}}{b + a}}{b - a}} \]
    6. Applied egg-rr63.6%

      \[\leadsto \color{blue}{\frac{\frac{\left(\frac{1}{a} + \frac{1}{b}\right) \cdot \left(\pi \cdot 0.5\right)}{b + a}}{b - a}} \]
    7. Taylor expanded in a around 0 63.6%

      \[\leadsto \frac{\color{blue}{0.5 \cdot \frac{\pi}{a \cdot b}}}{b - a} \]
    8. Step-by-step derivation
      1. associate-*r/63.6%

        \[\leadsto \frac{\color{blue}{\frac{0.5 \cdot \pi}{a \cdot b}}}{b - a} \]
    9. Simplified63.6%

      \[\leadsto \frac{\color{blue}{\frac{0.5 \cdot \pi}{a \cdot b}}}{b - a} \]
    10. Step-by-step derivation
      1. *-un-lft-identity63.6%

        \[\leadsto \color{blue}{1 \cdot \frac{\frac{0.5 \cdot \pi}{a \cdot b}}{b - a}} \]
      2. associate-/l/63.4%

        \[\leadsto 1 \cdot \color{blue}{\frac{0.5 \cdot \pi}{\left(b - a\right) \cdot \left(a \cdot b\right)}} \]
      3. *-commutative63.4%

        \[\leadsto 1 \cdot \frac{\color{blue}{\pi \cdot 0.5}}{\left(b - a\right) \cdot \left(a \cdot b\right)} \]
      4. *-commutative63.4%

        \[\leadsto 1 \cdot \frac{\pi \cdot 0.5}{\left(b - a\right) \cdot \color{blue}{\left(b \cdot a\right)}} \]
    11. Applied egg-rr63.4%

      \[\leadsto \color{blue}{1 \cdot \frac{\pi \cdot 0.5}{\left(b - a\right) \cdot \left(b \cdot a\right)}} \]
    12. Step-by-step derivation
      1. *-lft-identity63.4%

        \[\leadsto \color{blue}{\frac{\pi \cdot 0.5}{\left(b - a\right) \cdot \left(b \cdot a\right)}} \]
      2. times-frac63.5%

        \[\leadsto \color{blue}{\frac{\pi}{b - a} \cdot \frac{0.5}{b \cdot a}} \]
      3. *-commutative63.5%

        \[\leadsto \frac{\pi}{b - a} \cdot \frac{0.5}{\color{blue}{a \cdot b}} \]
    13. Simplified63.5%

      \[\leadsto \color{blue}{\frac{\pi}{b - a} \cdot \frac{0.5}{a \cdot b}} \]
    14. Taylor expanded in b around inf 67.9%

      \[\leadsto \color{blue}{\frac{\pi}{b}} \cdot \frac{0.5}{a \cdot b} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification67.9%

    \[\leadsto \begin{array}{l} \mathbf{if}\;a \leq -1.2 \cdot 10^{+109}:\\ \;\;\;\;\frac{\pi}{-a} \cdot \frac{0.5}{b \cdot a}\\ \mathbf{else}:\\ \;\;\;\;\frac{\pi}{b} \cdot \frac{0.5}{b \cdot a}\\ \end{array} \]
  5. Add Preprocessing

Alternative 3: 99.6% accurate, 1.9× speedup?

\[\begin{array}{l} \\ \frac{0.5}{b + a} \cdot \frac{\frac{\pi}{b}}{a} \end{array} \]
(FPCore (a b) :precision binary64 (* (/ 0.5 (+ b a)) (/ (/ PI b) a)))
double code(double a, double b) {
	return (0.5 / (b + a)) * ((((double) M_PI) / b) / a);
}
public static double code(double a, double b) {
	return (0.5 / (b + a)) * ((Math.PI / b) / a);
}
def code(a, b):
	return (0.5 / (b + a)) * ((math.pi / b) / a)
function code(a, b)
	return Float64(Float64(0.5 / Float64(b + a)) * Float64(Float64(pi / b) / a))
end
function tmp = code(a, b)
	tmp = (0.5 / (b + a)) * ((pi / b) / a);
end
code[a_, b_] := N[(N[(0.5 / N[(b + a), $MachinePrecision]), $MachinePrecision] * N[(N[(Pi / b), $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{0.5}{b + a} \cdot \frac{\frac{\pi}{b}}{a}
\end{array}
Derivation
  1. Initial program 77.1%

    \[\left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \]
  2. Step-by-step derivation
    1. *-commutative77.1%

      \[\leadsto \color{blue}{\left(\frac{1}{a} - \frac{1}{b}\right) \cdot \left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right)} \]
    2. associate-*r*77.1%

      \[\leadsto \color{blue}{\left(\left(\frac{1}{a} - \frac{1}{b}\right) \cdot \frac{\pi}{2}\right) \cdot \frac{1}{b \cdot b - a \cdot a}} \]
    3. associate-*r/77.1%

      \[\leadsto \color{blue}{\frac{\left(\left(\frac{1}{a} - \frac{1}{b}\right) \cdot \frac{\pi}{2}\right) \cdot 1}{b \cdot b - a \cdot a}} \]
    4. associate-*r*77.1%

      \[\leadsto \frac{\color{blue}{\left(\frac{1}{a} - \frac{1}{b}\right) \cdot \left(\frac{\pi}{2} \cdot 1\right)}}{b \cdot b - a \cdot a} \]
    5. *-rgt-identity77.1%

      \[\leadsto \frac{\left(\frac{1}{a} - \frac{1}{b}\right) \cdot \color{blue}{\frac{\pi}{2}}}{b \cdot b - a \cdot a} \]
    6. sub-neg77.1%

      \[\leadsto \frac{\color{blue}{\left(\frac{1}{a} + \left(-\frac{1}{b}\right)\right)} \cdot \frac{\pi}{2}}{b \cdot b - a \cdot a} \]
    7. distribute-neg-frac77.1%

      \[\leadsto \frac{\left(\frac{1}{a} + \color{blue}{\frac{-1}{b}}\right) \cdot \frac{\pi}{2}}{b \cdot b - a \cdot a} \]
    8. metadata-eval77.1%

      \[\leadsto \frac{\left(\frac{1}{a} + \frac{\color{blue}{-1}}{b}\right) \cdot \frac{\pi}{2}}{b \cdot b - a \cdot a} \]
  3. Simplified77.1%

    \[\leadsto \color{blue}{\frac{\left(\frac{1}{a} + \frac{-1}{b}\right) \cdot \frac{\pi}{2}}{b \cdot b - a \cdot a}} \]
  4. Add Preprocessing
  5. Taylor expanded in a around 0 54.5%

    \[\leadsto \frac{\color{blue}{0.5 \cdot \frac{\pi}{a}}}{b \cdot b - a \cdot a} \]
  6. Step-by-step derivation
    1. associate-*r/54.5%

      \[\leadsto \frac{\color{blue}{\frac{0.5 \cdot \pi}{a}}}{b \cdot b - a \cdot a} \]
  7. Simplified54.5%

    \[\leadsto \frac{\color{blue}{\frac{0.5 \cdot \pi}{a}}}{b \cdot b - a \cdot a} \]
  8. Step-by-step derivation
    1. associate-/l*54.5%

      \[\leadsto \frac{\color{blue}{0.5 \cdot \frac{\pi}{a}}}{b \cdot b - a \cdot a} \]
    2. difference-of-squares60.8%

      \[\leadsto \frac{0.5 \cdot \frac{\pi}{a}}{\color{blue}{\left(b + a\right) \cdot \left(b - a\right)}} \]
    3. times-frac65.8%

      \[\leadsto \color{blue}{\frac{0.5}{b + a} \cdot \frac{\frac{\pi}{a}}{b - a}} \]
  9. Applied egg-rr65.8%

    \[\leadsto \color{blue}{\frac{0.5}{b + a} \cdot \frac{\frac{\pi}{a}}{b - a}} \]
  10. Taylor expanded in a around 0 99.7%

    \[\leadsto \frac{0.5}{b + a} \cdot \color{blue}{\frac{\pi}{a \cdot b}} \]
  11. Step-by-step derivation
    1. associate-/l/99.6%

      \[\leadsto \frac{0.5}{b + a} \cdot \color{blue}{\frac{\frac{\pi}{b}}{a}} \]
  12. Simplified99.6%

    \[\leadsto \frac{0.5}{b + a} \cdot \color{blue}{\frac{\frac{\pi}{b}}{a}} \]
  13. Final simplification99.6%

    \[\leadsto \frac{0.5}{b + a} \cdot \frac{\frac{\pi}{b}}{a} \]
  14. Add Preprocessing

Alternative 4: 62.8% accurate, 2.3× speedup?

\[\begin{array}{l} \\ \frac{\pi}{b} \cdot \frac{0.5}{b \cdot a} \end{array} \]
(FPCore (a b) :precision binary64 (* (/ PI b) (/ 0.5 (* b a))))
double code(double a, double b) {
	return (((double) M_PI) / b) * (0.5 / (b * a));
}
public static double code(double a, double b) {
	return (Math.PI / b) * (0.5 / (b * a));
}
def code(a, b):
	return (math.pi / b) * (0.5 / (b * a))
function code(a, b)
	return Float64(Float64(pi / b) * Float64(0.5 / Float64(b * a)))
end
function tmp = code(a, b)
	tmp = (pi / b) * (0.5 / (b * a));
end
code[a_, b_] := N[(N[(Pi / b), $MachinePrecision] * N[(0.5 / N[(b * a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\pi}{b} \cdot \frac{0.5}{b \cdot a}
\end{array}
Derivation
  1. Initial program 77.1%

    \[\left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \]
  2. Step-by-step derivation
    1. associate-*l*77.1%

      \[\leadsto \color{blue}{\frac{\pi}{2} \cdot \left(\frac{1}{b \cdot b - a \cdot a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)\right)} \]
    2. *-rgt-identity77.1%

      \[\leadsto \frac{\color{blue}{\pi \cdot 1}}{2} \cdot \left(\frac{1}{b \cdot b - a \cdot a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)\right) \]
    3. associate-/l*77.1%

      \[\leadsto \color{blue}{\left(\pi \cdot \frac{1}{2}\right)} \cdot \left(\frac{1}{b \cdot b - a \cdot a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)\right) \]
    4. metadata-eval77.1%

      \[\leadsto \left(\pi \cdot \color{blue}{0.5}\right) \cdot \left(\frac{1}{b \cdot b - a \cdot a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)\right) \]
    5. associate-*l/77.1%

      \[\leadsto \left(\pi \cdot 0.5\right) \cdot \color{blue}{\frac{1 \cdot \left(\frac{1}{a} - \frac{1}{b}\right)}{b \cdot b - a \cdot a}} \]
    6. *-lft-identity77.1%

      \[\leadsto \left(\pi \cdot 0.5\right) \cdot \frac{\color{blue}{\frac{1}{a} - \frac{1}{b}}}{b \cdot b - a \cdot a} \]
    7. sub-neg77.1%

      \[\leadsto \left(\pi \cdot 0.5\right) \cdot \frac{\color{blue}{\frac{1}{a} + \left(-\frac{1}{b}\right)}}{b \cdot b - a \cdot a} \]
    8. distribute-neg-frac77.1%

      \[\leadsto \left(\pi \cdot 0.5\right) \cdot \frac{\frac{1}{a} + \color{blue}{\frac{-1}{b}}}{b \cdot b - a \cdot a} \]
    9. metadata-eval77.1%

      \[\leadsto \left(\pi \cdot 0.5\right) \cdot \frac{\frac{1}{a} + \frac{\color{blue}{-1}}{b}}{b \cdot b - a \cdot a} \]
  3. Simplified77.1%

    \[\leadsto \color{blue}{\left(\pi \cdot 0.5\right) \cdot \frac{\frac{1}{a} + \frac{-1}{b}}{b \cdot b - a \cdot a}} \]
  4. Add Preprocessing
  5. Step-by-step derivation
    1. metadata-eval77.1%

      \[\leadsto \left(\pi \cdot \color{blue}{\frac{1}{2}}\right) \cdot \frac{\frac{1}{a} + \frac{-1}{b}}{b \cdot b - a \cdot a} \]
    2. div-inv77.1%

      \[\leadsto \color{blue}{\frac{\pi}{2}} \cdot \frac{\frac{1}{a} + \frac{-1}{b}}{b \cdot b - a \cdot a} \]
    3. associate-*r/77.1%

      \[\leadsto \color{blue}{\frac{\frac{\pi}{2} \cdot \left(\frac{1}{a} + \frac{-1}{b}\right)}{b \cdot b - a \cdot a}} \]
    4. *-commutative77.1%

      \[\leadsto \frac{\color{blue}{\left(\frac{1}{a} + \frac{-1}{b}\right) \cdot \frac{\pi}{2}}}{b \cdot b - a \cdot a} \]
    5. difference-of-squares86.5%

      \[\leadsto \frac{\left(\frac{1}{a} + \frac{-1}{b}\right) \cdot \frac{\pi}{2}}{\color{blue}{\left(b + a\right) \cdot \left(b - a\right)}} \]
    6. associate-/r*99.6%

      \[\leadsto \color{blue}{\frac{\frac{\left(\frac{1}{a} + \frac{-1}{b}\right) \cdot \frac{\pi}{2}}{b + a}}{b - a}} \]
  6. Applied egg-rr64.4%

    \[\leadsto \color{blue}{\frac{\frac{\left(\frac{1}{a} + \frac{1}{b}\right) \cdot \left(\pi \cdot 0.5\right)}{b + a}}{b - a}} \]
  7. Taylor expanded in a around 0 64.4%

    \[\leadsto \frac{\color{blue}{0.5 \cdot \frac{\pi}{a \cdot b}}}{b - a} \]
  8. Step-by-step derivation
    1. associate-*r/64.4%

      \[\leadsto \frac{\color{blue}{\frac{0.5 \cdot \pi}{a \cdot b}}}{b - a} \]
  9. Simplified64.4%

    \[\leadsto \frac{\color{blue}{\frac{0.5 \cdot \pi}{a \cdot b}}}{b - a} \]
  10. Step-by-step derivation
    1. *-un-lft-identity64.4%

      \[\leadsto \color{blue}{1 \cdot \frac{\frac{0.5 \cdot \pi}{a \cdot b}}{b - a}} \]
    2. associate-/l/64.3%

      \[\leadsto 1 \cdot \color{blue}{\frac{0.5 \cdot \pi}{\left(b - a\right) \cdot \left(a \cdot b\right)}} \]
    3. *-commutative64.3%

      \[\leadsto 1 \cdot \frac{\color{blue}{\pi \cdot 0.5}}{\left(b - a\right) \cdot \left(a \cdot b\right)} \]
    4. *-commutative64.3%

      \[\leadsto 1 \cdot \frac{\pi \cdot 0.5}{\left(b - a\right) \cdot \color{blue}{\left(b \cdot a\right)}} \]
  11. Applied egg-rr64.3%

    \[\leadsto \color{blue}{1 \cdot \frac{\pi \cdot 0.5}{\left(b - a\right) \cdot \left(b \cdot a\right)}} \]
  12. Step-by-step derivation
    1. *-lft-identity64.3%

      \[\leadsto \color{blue}{\frac{\pi \cdot 0.5}{\left(b - a\right) \cdot \left(b \cdot a\right)}} \]
    2. times-frac64.4%

      \[\leadsto \color{blue}{\frac{\pi}{b - a} \cdot \frac{0.5}{b \cdot a}} \]
    3. *-commutative64.4%

      \[\leadsto \frac{\pi}{b - a} \cdot \frac{0.5}{\color{blue}{a \cdot b}} \]
  13. Simplified64.4%

    \[\leadsto \color{blue}{\frac{\pi}{b - a} \cdot \frac{0.5}{a \cdot b}} \]
  14. Taylor expanded in b around inf 63.4%

    \[\leadsto \color{blue}{\frac{\pi}{b}} \cdot \frac{0.5}{a \cdot b} \]
  15. Final simplification63.4%

    \[\leadsto \frac{\pi}{b} \cdot \frac{0.5}{b \cdot a} \]
  16. Add Preprocessing

Reproduce

?
herbie shell --seed 2024053 
(FPCore (a b)
  :name "NMSE Section 6.1 mentioned, B"
  :precision binary64
  (* (* (/ PI 2.0) (/ 1.0 (- (* b b) (* a a)))) (- (/ 1.0 a) (/ 1.0 b))))