Ian Simplification

Percentage Accurate: 6.7% → 8.2%
Time: 30.0s
Alternatives: 10
Speedup: 1.0×

Specification

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

\\
\frac{\pi}{2} - 2 \cdot \sin^{-1} \left(\sqrt{\frac{1 - x}{2}}\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 10 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: 6.7% accurate, 1.0× speedup?

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

\\
\frac{\pi}{2} - 2 \cdot \sin^{-1} \left(\sqrt{\frac{1 - x}{2}}\right)
\end{array}

Alternative 1: 8.2% accurate, 0.1× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right)\\ t_1 := \pi \cdot 0.5 - \cos^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right)\\ t_2 := {t_1}^{3} \cdot 8\\ t_3 := {t_1}^{9}\\ \frac{\frac{\frac{\mathsf{fma}\left({\left({\pi}^{9}\right)}^{3}, 7.450580596923828 \cdot 10^{-9}, {t_3}^{3} \cdot -134217728\right)}{{\pi}^{18} \cdot 3.814697265625 \cdot 10^{-6} + \mathsf{fma}\left({\pi}^{9}, t_3, {t_1}^{18} \cdot 262144\right)}}{{\pi}^{6} \cdot 0.015625 + \left({t_2}^{2} + t_2 \cdot \left({\pi}^{3} \cdot 0.125\right)\right)}}{\mathsf{fma}\left(2 \cdot t_0, \mathsf{fma}\left(2, t_0, \pi \cdot 0.5\right), {\pi}^{2} \cdot 0.25\right)} \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (let* ((t_0 (asin (sqrt (- 0.5 (* 0.5 x)))))
        (t_1 (- (* PI 0.5) (acos (sqrt (fma x -0.5 0.5)))))
        (t_2 (* (pow t_1 3.0) 8.0))
        (t_3 (pow t_1 9.0)))
   (/
    (/
     (/
      (fma
       (pow (pow PI 9.0) 3.0)
       7.450580596923828e-9
       (* (pow t_3 3.0) -134217728.0))
      (+
       (* (pow PI 18.0) 3.814697265625e-6)
       (fma (pow PI 9.0) t_3 (* (pow t_1 18.0) 262144.0))))
     (+
      (* (pow PI 6.0) 0.015625)
      (+ (pow t_2 2.0) (* t_2 (* (pow PI 3.0) 0.125)))))
    (fma (* 2.0 t_0) (fma 2.0 t_0 (* PI 0.5)) (* (pow PI 2.0) 0.25)))))
double code(double x) {
	double t_0 = asin(sqrt((0.5 - (0.5 * x))));
	double t_1 = (((double) M_PI) * 0.5) - acos(sqrt(fma(x, -0.5, 0.5)));
	double t_2 = pow(t_1, 3.0) * 8.0;
	double t_3 = pow(t_1, 9.0);
	return ((fma(pow(pow(((double) M_PI), 9.0), 3.0), 7.450580596923828e-9, (pow(t_3, 3.0) * -134217728.0)) / ((pow(((double) M_PI), 18.0) * 3.814697265625e-6) + fma(pow(((double) M_PI), 9.0), t_3, (pow(t_1, 18.0) * 262144.0)))) / ((pow(((double) M_PI), 6.0) * 0.015625) + (pow(t_2, 2.0) + (t_2 * (pow(((double) M_PI), 3.0) * 0.125))))) / fma((2.0 * t_0), fma(2.0, t_0, (((double) M_PI) * 0.5)), (pow(((double) M_PI), 2.0) * 0.25));
}
function code(x)
	t_0 = asin(sqrt(Float64(0.5 - Float64(0.5 * x))))
	t_1 = Float64(Float64(pi * 0.5) - acos(sqrt(fma(x, -0.5, 0.5))))
	t_2 = Float64((t_1 ^ 3.0) * 8.0)
	t_3 = t_1 ^ 9.0
	return Float64(Float64(Float64(fma(((pi ^ 9.0) ^ 3.0), 7.450580596923828e-9, Float64((t_3 ^ 3.0) * -134217728.0)) / Float64(Float64((pi ^ 18.0) * 3.814697265625e-6) + fma((pi ^ 9.0), t_3, Float64((t_1 ^ 18.0) * 262144.0)))) / Float64(Float64((pi ^ 6.0) * 0.015625) + Float64((t_2 ^ 2.0) + Float64(t_2 * Float64((pi ^ 3.0) * 0.125))))) / fma(Float64(2.0 * t_0), fma(2.0, t_0, Float64(pi * 0.5)), Float64((pi ^ 2.0) * 0.25)))
end
code[x_] := Block[{t$95$0 = N[ArcSin[N[Sqrt[N[(0.5 - N[(0.5 * x), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]}, Block[{t$95$1 = N[(N[(Pi * 0.5), $MachinePrecision] - N[ArcCos[N[Sqrt[N[(x * -0.5 + 0.5), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, Block[{t$95$2 = N[(N[Power[t$95$1, 3.0], $MachinePrecision] * 8.0), $MachinePrecision]}, Block[{t$95$3 = N[Power[t$95$1, 9.0], $MachinePrecision]}, N[(N[(N[(N[(N[Power[N[Power[Pi, 9.0], $MachinePrecision], 3.0], $MachinePrecision] * 7.450580596923828e-9 + N[(N[Power[t$95$3, 3.0], $MachinePrecision] * -134217728.0), $MachinePrecision]), $MachinePrecision] / N[(N[(N[Power[Pi, 18.0], $MachinePrecision] * 3.814697265625e-6), $MachinePrecision] + N[(N[Power[Pi, 9.0], $MachinePrecision] * t$95$3 + N[(N[Power[t$95$1, 18.0], $MachinePrecision] * 262144.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(N[(N[Power[Pi, 6.0], $MachinePrecision] * 0.015625), $MachinePrecision] + N[(N[Power[t$95$2, 2.0], $MachinePrecision] + N[(t$95$2 * N[(N[Power[Pi, 3.0], $MachinePrecision] * 0.125), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(N[(2.0 * t$95$0), $MachinePrecision] * N[(2.0 * t$95$0 + N[(Pi * 0.5), $MachinePrecision]), $MachinePrecision] + N[(N[Power[Pi, 2.0], $MachinePrecision] * 0.25), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right)\\
t_1 := \pi \cdot 0.5 - \cos^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right)\\
t_2 := {t_1}^{3} \cdot 8\\
t_3 := {t_1}^{9}\\
\frac{\frac{\frac{\mathsf{fma}\left({\left({\pi}^{9}\right)}^{3}, 7.450580596923828 \cdot 10^{-9}, {t_3}^{3} \cdot -134217728\right)}{{\pi}^{18} \cdot 3.814697265625 \cdot 10^{-6} + \mathsf{fma}\left({\pi}^{9}, t_3, {t_1}^{18} \cdot 262144\right)}}{{\pi}^{6} \cdot 0.015625 + \left({t_2}^{2} + t_2 \cdot \left({\pi}^{3} \cdot 0.125\right)\right)}}{\mathsf{fma}\left(2 \cdot t_0, \mathsf{fma}\left(2, t_0, \pi \cdot 0.5\right), {\pi}^{2} \cdot 0.25\right)}
\end{array}
\end{array}
Derivation
    &prev;&pcontext;&pcontext2;&ctx;
  1. Add Preprocessing

Alternative 2: 8.1% accurate, 0.1× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right)\\ t_1 := \pi \cdot 0.5 - \cos^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right)\\ t_2 := {t_1}^{3} \cdot 8\\ \frac{\frac{\log \left(e^{{\pi}^{9} \cdot 0.001953125 - {t_1}^{9} \cdot 512}\right)}{{\pi}^{6} \cdot 0.015625 + \left({t_2}^{2} + t_2 \cdot \left({\pi}^{3} \cdot 0.125\right)\right)}}{\mathsf{fma}\left(2 \cdot t_0, \mathsf{fma}\left(2, t_0, \pi \cdot 0.5\right), {\pi}^{2} \cdot 0.25\right)} \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (let* ((t_0 (asin (sqrt (- 0.5 (* 0.5 x)))))
        (t_1 (- (* PI 0.5) (acos (sqrt (fma x -0.5 0.5)))))
        (t_2 (* (pow t_1 3.0) 8.0)))
   (/
    (/
     (log (exp (- (* (pow PI 9.0) 0.001953125) (* (pow t_1 9.0) 512.0))))
     (+
      (* (pow PI 6.0) 0.015625)
      (+ (pow t_2 2.0) (* t_2 (* (pow PI 3.0) 0.125)))))
    (fma (* 2.0 t_0) (fma 2.0 t_0 (* PI 0.5)) (* (pow PI 2.0) 0.25)))))
double code(double x) {
	double t_0 = asin(sqrt((0.5 - (0.5 * x))));
	double t_1 = (((double) M_PI) * 0.5) - acos(sqrt(fma(x, -0.5, 0.5)));
	double t_2 = pow(t_1, 3.0) * 8.0;
	return (log(exp(((pow(((double) M_PI), 9.0) * 0.001953125) - (pow(t_1, 9.0) * 512.0)))) / ((pow(((double) M_PI), 6.0) * 0.015625) + (pow(t_2, 2.0) + (t_2 * (pow(((double) M_PI), 3.0) * 0.125))))) / fma((2.0 * t_0), fma(2.0, t_0, (((double) M_PI) * 0.5)), (pow(((double) M_PI), 2.0) * 0.25));
}
function code(x)
	t_0 = asin(sqrt(Float64(0.5 - Float64(0.5 * x))))
	t_1 = Float64(Float64(pi * 0.5) - acos(sqrt(fma(x, -0.5, 0.5))))
	t_2 = Float64((t_1 ^ 3.0) * 8.0)
	return Float64(Float64(log(exp(Float64(Float64((pi ^ 9.0) * 0.001953125) - Float64((t_1 ^ 9.0) * 512.0)))) / Float64(Float64((pi ^ 6.0) * 0.015625) + Float64((t_2 ^ 2.0) + Float64(t_2 * Float64((pi ^ 3.0) * 0.125))))) / fma(Float64(2.0 * t_0), fma(2.0, t_0, Float64(pi * 0.5)), Float64((pi ^ 2.0) * 0.25)))
end
code[x_] := Block[{t$95$0 = N[ArcSin[N[Sqrt[N[(0.5 - N[(0.5 * x), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]}, Block[{t$95$1 = N[(N[(Pi * 0.5), $MachinePrecision] - N[ArcCos[N[Sqrt[N[(x * -0.5 + 0.5), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, Block[{t$95$2 = N[(N[Power[t$95$1, 3.0], $MachinePrecision] * 8.0), $MachinePrecision]}, N[(N[(N[Log[N[Exp[N[(N[(N[Power[Pi, 9.0], $MachinePrecision] * 0.001953125), $MachinePrecision] - N[(N[Power[t$95$1, 9.0], $MachinePrecision] * 512.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision] / N[(N[(N[Power[Pi, 6.0], $MachinePrecision] * 0.015625), $MachinePrecision] + N[(N[Power[t$95$2, 2.0], $MachinePrecision] + N[(t$95$2 * N[(N[Power[Pi, 3.0], $MachinePrecision] * 0.125), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(N[(2.0 * t$95$0), $MachinePrecision] * N[(2.0 * t$95$0 + N[(Pi * 0.5), $MachinePrecision]), $MachinePrecision] + N[(N[Power[Pi, 2.0], $MachinePrecision] * 0.25), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right)\\
t_1 := \pi \cdot 0.5 - \cos^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right)\\
t_2 := {t_1}^{3} \cdot 8\\
\frac{\frac{\log \left(e^{{\pi}^{9} \cdot 0.001953125 - {t_1}^{9} \cdot 512}\right)}{{\pi}^{6} \cdot 0.015625 + \left({t_2}^{2} + t_2 \cdot \left({\pi}^{3} \cdot 0.125\right)\right)}}{\mathsf{fma}\left(2 \cdot t_0, \mathsf{fma}\left(2, t_0, \pi \cdot 0.5\right), {\pi}^{2} \cdot 0.25\right)}
\end{array}
\end{array}
Derivation
    &prev;&pcontext;&pcontext2;&ctx;
  1. Add Preprocessing

Alternative 3: 8.2% accurate, 0.1× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right)\\ t_1 := \pi \cdot 0.5 - \cos^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right)\\ t_2 := {t_1}^{3} \cdot 8\\ \frac{\frac{{\pi}^{9} \cdot 0.001953125 - {t_1}^{9} \cdot 512}{{\pi}^{6} \cdot 0.015625 + \left({t_2}^{2} + t_2 \cdot \left({\pi}^{3} \cdot 0.125\right)\right)}}{\mathsf{fma}\left(2 \cdot t_0, \mathsf{fma}\left(2, t_0, \pi \cdot 0.5\right), {\pi}^{2} \cdot 0.25\right)} \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (let* ((t_0 (asin (sqrt (- 0.5 (* 0.5 x)))))
        (t_1 (- (* PI 0.5) (acos (sqrt (fma x -0.5 0.5)))))
        (t_2 (* (pow t_1 3.0) 8.0)))
   (/
    (/
     (- (* (pow PI 9.0) 0.001953125) (* (pow t_1 9.0) 512.0))
     (+
      (* (pow PI 6.0) 0.015625)
      (+ (pow t_2 2.0) (* t_2 (* (pow PI 3.0) 0.125)))))
    (fma (* 2.0 t_0) (fma 2.0 t_0 (* PI 0.5)) (* (pow PI 2.0) 0.25)))))
double code(double x) {
	double t_0 = asin(sqrt((0.5 - (0.5 * x))));
	double t_1 = (((double) M_PI) * 0.5) - acos(sqrt(fma(x, -0.5, 0.5)));
	double t_2 = pow(t_1, 3.0) * 8.0;
	return (((pow(((double) M_PI), 9.0) * 0.001953125) - (pow(t_1, 9.0) * 512.0)) / ((pow(((double) M_PI), 6.0) * 0.015625) + (pow(t_2, 2.0) + (t_2 * (pow(((double) M_PI), 3.0) * 0.125))))) / fma((2.0 * t_0), fma(2.0, t_0, (((double) M_PI) * 0.5)), (pow(((double) M_PI), 2.0) * 0.25));
}
function code(x)
	t_0 = asin(sqrt(Float64(0.5 - Float64(0.5 * x))))
	t_1 = Float64(Float64(pi * 0.5) - acos(sqrt(fma(x, -0.5, 0.5))))
	t_2 = Float64((t_1 ^ 3.0) * 8.0)
	return Float64(Float64(Float64(Float64((pi ^ 9.0) * 0.001953125) - Float64((t_1 ^ 9.0) * 512.0)) / Float64(Float64((pi ^ 6.0) * 0.015625) + Float64((t_2 ^ 2.0) + Float64(t_2 * Float64((pi ^ 3.0) * 0.125))))) / fma(Float64(2.0 * t_0), fma(2.0, t_0, Float64(pi * 0.5)), Float64((pi ^ 2.0) * 0.25)))
end
code[x_] := Block[{t$95$0 = N[ArcSin[N[Sqrt[N[(0.5 - N[(0.5 * x), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]}, Block[{t$95$1 = N[(N[(Pi * 0.5), $MachinePrecision] - N[ArcCos[N[Sqrt[N[(x * -0.5 + 0.5), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, Block[{t$95$2 = N[(N[Power[t$95$1, 3.0], $MachinePrecision] * 8.0), $MachinePrecision]}, N[(N[(N[(N[(N[Power[Pi, 9.0], $MachinePrecision] * 0.001953125), $MachinePrecision] - N[(N[Power[t$95$1, 9.0], $MachinePrecision] * 512.0), $MachinePrecision]), $MachinePrecision] / N[(N[(N[Power[Pi, 6.0], $MachinePrecision] * 0.015625), $MachinePrecision] + N[(N[Power[t$95$2, 2.0], $MachinePrecision] + N[(t$95$2 * N[(N[Power[Pi, 3.0], $MachinePrecision] * 0.125), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(N[(2.0 * t$95$0), $MachinePrecision] * N[(2.0 * t$95$0 + N[(Pi * 0.5), $MachinePrecision]), $MachinePrecision] + N[(N[Power[Pi, 2.0], $MachinePrecision] * 0.25), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right)\\
t_1 := \pi \cdot 0.5 - \cos^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right)\\
t_2 := {t_1}^{3} \cdot 8\\
\frac{\frac{{\pi}^{9} \cdot 0.001953125 - {t_1}^{9} \cdot 512}{{\pi}^{6} \cdot 0.015625 + \left({t_2}^{2} + t_2 \cdot \left({\pi}^{3} \cdot 0.125\right)\right)}}{\mathsf{fma}\left(2 \cdot t_0, \mathsf{fma}\left(2, t_0, \pi \cdot 0.5\right), {\pi}^{2} \cdot 0.25\right)}
\end{array}
\end{array}
Derivation
    &prev;&pcontext;&pcontext2;&ctx;
  1. Add Preprocessing

Alternative 4: 8.2% accurate, 0.2× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right)\\ \frac{\log \left(e^{{\pi}^{3} \cdot 0.125 - {\left(\pi \cdot 0.5 - \cos^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right)\right)}^{3} \cdot 8}\right)}{\mathsf{fma}\left(2 \cdot t_0, \mathsf{fma}\left(2, t_0, \pi \cdot 0.5\right), {\pi}^{2} \cdot 0.25\right)} \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (let* ((t_0 (asin (sqrt (- 0.5 (* 0.5 x))))))
   (/
    (log
     (exp
      (-
       (* (pow PI 3.0) 0.125)
       (* (pow (- (* PI 0.5) (acos (sqrt (fma x -0.5 0.5)))) 3.0) 8.0))))
    (fma (* 2.0 t_0) (fma 2.0 t_0 (* PI 0.5)) (* (pow PI 2.0) 0.25)))))
double code(double x) {
	double t_0 = asin(sqrt((0.5 - (0.5 * x))));
	return log(exp(((pow(((double) M_PI), 3.0) * 0.125) - (pow(((((double) M_PI) * 0.5) - acos(sqrt(fma(x, -0.5, 0.5)))), 3.0) * 8.0)))) / fma((2.0 * t_0), fma(2.0, t_0, (((double) M_PI) * 0.5)), (pow(((double) M_PI), 2.0) * 0.25));
}
function code(x)
	t_0 = asin(sqrt(Float64(0.5 - Float64(0.5 * x))))
	return Float64(log(exp(Float64(Float64((pi ^ 3.0) * 0.125) - Float64((Float64(Float64(pi * 0.5) - acos(sqrt(fma(x, -0.5, 0.5)))) ^ 3.0) * 8.0)))) / fma(Float64(2.0 * t_0), fma(2.0, t_0, Float64(pi * 0.5)), Float64((pi ^ 2.0) * 0.25)))
end
code[x_] := Block[{t$95$0 = N[ArcSin[N[Sqrt[N[(0.5 - N[(0.5 * x), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]}, N[(N[Log[N[Exp[N[(N[(N[Power[Pi, 3.0], $MachinePrecision] * 0.125), $MachinePrecision] - N[(N[Power[N[(N[(Pi * 0.5), $MachinePrecision] - N[ArcCos[N[Sqrt[N[(x * -0.5 + 0.5), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]), $MachinePrecision], 3.0], $MachinePrecision] * 8.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision] / N[(N[(2.0 * t$95$0), $MachinePrecision] * N[(2.0 * t$95$0 + N[(Pi * 0.5), $MachinePrecision]), $MachinePrecision] + N[(N[Power[Pi, 2.0], $MachinePrecision] * 0.25), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right)\\
\frac{\log \left(e^{{\pi}^{3} \cdot 0.125 - {\left(\pi \cdot 0.5 - \cos^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right)\right)}^{3} \cdot 8}\right)}{\mathsf{fma}\left(2 \cdot t_0, \mathsf{fma}\left(2, t_0, \pi \cdot 0.5\right), {\pi}^{2} \cdot 0.25\right)}
\end{array}
\end{array}
Derivation
    &prev;&pcontext;&pcontext2;&ctx;
  1. Add Preprocessing

Alternative 5: 8.2% accurate, 0.2× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \pi \cdot 0.5 - \cos^{-1} \left(\sqrt{0.5 + x \cdot -0.5}\right)\\ \frac{{\pi}^{3} \cdot 0.125 - 8 \cdot {t_0}^{3}}{\mathsf{fma}\left(2 \cdot t_0, \mathsf{fma}\left(2, \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right), \pi \cdot 0.5\right), {\pi}^{2} \cdot 0.25\right)} \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (let* ((t_0 (- (* PI 0.5) (acos (sqrt (+ 0.5 (* x -0.5)))))))
   (/
    (- (* (pow PI 3.0) 0.125) (* 8.0 (pow t_0 3.0)))
    (fma
     (* 2.0 t_0)
     (fma 2.0 (asin (sqrt (- 0.5 (* 0.5 x)))) (* PI 0.5))
     (* (pow PI 2.0) 0.25)))))
double code(double x) {
	double t_0 = (((double) M_PI) * 0.5) - acos(sqrt((0.5 + (x * -0.5))));
	return ((pow(((double) M_PI), 3.0) * 0.125) - (8.0 * pow(t_0, 3.0))) / fma((2.0 * t_0), fma(2.0, asin(sqrt((0.5 - (0.5 * x)))), (((double) M_PI) * 0.5)), (pow(((double) M_PI), 2.0) * 0.25));
}
function code(x)
	t_0 = Float64(Float64(pi * 0.5) - acos(sqrt(Float64(0.5 + Float64(x * -0.5)))))
	return Float64(Float64(Float64((pi ^ 3.0) * 0.125) - Float64(8.0 * (t_0 ^ 3.0))) / fma(Float64(2.0 * t_0), fma(2.0, asin(sqrt(Float64(0.5 - Float64(0.5 * x)))), Float64(pi * 0.5)), Float64((pi ^ 2.0) * 0.25)))
end
code[x_] := Block[{t$95$0 = N[(N[(Pi * 0.5), $MachinePrecision] - N[ArcCos[N[Sqrt[N[(0.5 + N[(x * -0.5), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, N[(N[(N[(N[Power[Pi, 3.0], $MachinePrecision] * 0.125), $MachinePrecision] - N[(8.0 * N[Power[t$95$0, 3.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(N[(2.0 * t$95$0), $MachinePrecision] * N[(2.0 * N[ArcSin[N[Sqrt[N[(0.5 - N[(0.5 * x), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision] + N[(Pi * 0.5), $MachinePrecision]), $MachinePrecision] + N[(N[Power[Pi, 2.0], $MachinePrecision] * 0.25), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \pi \cdot 0.5 - \cos^{-1} \left(\sqrt{0.5 + x \cdot -0.5}\right)\\
\frac{{\pi}^{3} \cdot 0.125 - 8 \cdot {t_0}^{3}}{\mathsf{fma}\left(2 \cdot t_0, \mathsf{fma}\left(2, \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right), \pi \cdot 0.5\right), {\pi}^{2} \cdot 0.25\right)}
\end{array}
\end{array}
Derivation
    &prev;&pcontext;&pcontext2;&ctx;
  1. Add Preprocessing

Alternative 6: 8.2% accurate, 0.2× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right)\\ \frac{{\pi}^{3} \cdot 0.125 - 8 \cdot {\left(\pi \cdot 0.5 - \cos^{-1} \left(\sqrt{0.5 + x \cdot -0.5}\right)\right)}^{3}}{\mathsf{fma}\left(2 \cdot t_0, \mathsf{fma}\left(2, t_0, \pi \cdot 0.5\right), {\pi}^{2} \cdot 0.25\right)} \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (let* ((t_0 (asin (sqrt (- 0.5 (* 0.5 x))))))
   (/
    (-
     (* (pow PI 3.0) 0.125)
     (* 8.0 (pow (- (* PI 0.5) (acos (sqrt (+ 0.5 (* x -0.5))))) 3.0)))
    (fma (* 2.0 t_0) (fma 2.0 t_0 (* PI 0.5)) (* (pow PI 2.0) 0.25)))))
double code(double x) {
	double t_0 = asin(sqrt((0.5 - (0.5 * x))));
	return ((pow(((double) M_PI), 3.0) * 0.125) - (8.0 * pow(((((double) M_PI) * 0.5) - acos(sqrt((0.5 + (x * -0.5))))), 3.0))) / fma((2.0 * t_0), fma(2.0, t_0, (((double) M_PI) * 0.5)), (pow(((double) M_PI), 2.0) * 0.25));
}
function code(x)
	t_0 = asin(sqrt(Float64(0.5 - Float64(0.5 * x))))
	return Float64(Float64(Float64((pi ^ 3.0) * 0.125) - Float64(8.0 * (Float64(Float64(pi * 0.5) - acos(sqrt(Float64(0.5 + Float64(x * -0.5))))) ^ 3.0))) / fma(Float64(2.0 * t_0), fma(2.0, t_0, Float64(pi * 0.5)), Float64((pi ^ 2.0) * 0.25)))
end
code[x_] := Block[{t$95$0 = N[ArcSin[N[Sqrt[N[(0.5 - N[(0.5 * x), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]}, N[(N[(N[(N[Power[Pi, 3.0], $MachinePrecision] * 0.125), $MachinePrecision] - N[(8.0 * N[Power[N[(N[(Pi * 0.5), $MachinePrecision] - N[ArcCos[N[Sqrt[N[(0.5 + N[(x * -0.5), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]), $MachinePrecision], 3.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(N[(2.0 * t$95$0), $MachinePrecision] * N[(2.0 * t$95$0 + N[(Pi * 0.5), $MachinePrecision]), $MachinePrecision] + N[(N[Power[Pi, 2.0], $MachinePrecision] * 0.25), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right)\\
\frac{{\pi}^{3} \cdot 0.125 - 8 \cdot {\left(\pi \cdot 0.5 - \cos^{-1} \left(\sqrt{0.5 + x \cdot -0.5}\right)\right)}^{3}}{\mathsf{fma}\left(2 \cdot t_0, \mathsf{fma}\left(2, t_0, \pi \cdot 0.5\right), {\pi}^{2} \cdot 0.25\right)}
\end{array}
\end{array}
Derivation
    &prev;&pcontext;&pcontext2;&ctx;
  1. Add Preprocessing

Alternative 7: 8.2% accurate, 0.3× speedup?

\[\begin{array}{l} \\ \frac{1}{\frac{\mathsf{fma}\left(2, \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right), \pi \cdot 0.5\right)}{{\pi}^{2} \cdot 0.25 - {\left(\pi \cdot 0.5 - \cos^{-1} \left(\sqrt{0.5 + x \cdot -0.5}\right)\right)}^{2} \cdot 4}} \end{array} \]
(FPCore (x)
 :precision binary64
 (/
  1.0
  (/
   (fma 2.0 (asin (sqrt (- 0.5 (* 0.5 x)))) (* PI 0.5))
   (-
    (* (pow PI 2.0) 0.25)
    (* (pow (- (* PI 0.5) (acos (sqrt (+ 0.5 (* x -0.5))))) 2.0) 4.0)))))
double code(double x) {
	return 1.0 / (fma(2.0, asin(sqrt((0.5 - (0.5 * x)))), (((double) M_PI) * 0.5)) / ((pow(((double) M_PI), 2.0) * 0.25) - (pow(((((double) M_PI) * 0.5) - acos(sqrt((0.5 + (x * -0.5))))), 2.0) * 4.0)));
}
function code(x)
	return Float64(1.0 / Float64(fma(2.0, asin(sqrt(Float64(0.5 - Float64(0.5 * x)))), Float64(pi * 0.5)) / Float64(Float64((pi ^ 2.0) * 0.25) - Float64((Float64(Float64(pi * 0.5) - acos(sqrt(Float64(0.5 + Float64(x * -0.5))))) ^ 2.0) * 4.0))))
end
code[x_] := N[(1.0 / N[(N[(2.0 * N[ArcSin[N[Sqrt[N[(0.5 - N[(0.5 * x), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision] + N[(Pi * 0.5), $MachinePrecision]), $MachinePrecision] / N[(N[(N[Power[Pi, 2.0], $MachinePrecision] * 0.25), $MachinePrecision] - N[(N[Power[N[(N[(Pi * 0.5), $MachinePrecision] - N[ArcCos[N[Sqrt[N[(0.5 + N[(x * -0.5), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]), $MachinePrecision], 2.0], $MachinePrecision] * 4.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{1}{\frac{\mathsf{fma}\left(2, \sin^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right), \pi \cdot 0.5\right)}{{\pi}^{2} \cdot 0.25 - {\left(\pi \cdot 0.5 - \cos^{-1} \left(\sqrt{0.5 + x \cdot -0.5}\right)\right)}^{2} \cdot 4}}
\end{array}
Derivation
    &prev;&pcontext;&pcontext2;&ctx;
  1. Add Preprocessing

Alternative 8: 8.2% accurate, 0.8× speedup?

\[\begin{array}{l} \\ \frac{\pi}{2} + 2 \cdot \left(\cos^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right) - \pi \cdot 0.5\right) \end{array} \]
(FPCore (x)
 :precision binary64
 (+ (/ PI 2.0) (* 2.0 (- (acos (sqrt (- 0.5 (* 0.5 x)))) (* PI 0.5)))))
double code(double x) {
	return (((double) M_PI) / 2.0) + (2.0 * (acos(sqrt((0.5 - (0.5 * x)))) - (((double) M_PI) * 0.5)));
}
public static double code(double x) {
	return (Math.PI / 2.0) + (2.0 * (Math.acos(Math.sqrt((0.5 - (0.5 * x)))) - (Math.PI * 0.5)));
}
def code(x):
	return (math.pi / 2.0) + (2.0 * (math.acos(math.sqrt((0.5 - (0.5 * x)))) - (math.pi * 0.5)))
function code(x)
	return Float64(Float64(pi / 2.0) + Float64(2.0 * Float64(acos(sqrt(Float64(0.5 - Float64(0.5 * x)))) - Float64(pi * 0.5))))
end
function tmp = code(x)
	tmp = (pi / 2.0) + (2.0 * (acos(sqrt((0.5 - (0.5 * x)))) - (pi * 0.5)));
end
code[x_] := N[(N[(Pi / 2.0), $MachinePrecision] + N[(2.0 * N[(N[ArcCos[N[Sqrt[N[(0.5 - N[(0.5 * x), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision] - N[(Pi * 0.5), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\pi}{2} + 2 \cdot \left(\cos^{-1} \left(\sqrt{0.5 - 0.5 \cdot x}\right) - \pi \cdot 0.5\right)
\end{array}
Derivation
    &prev;&pcontext;&pcontext2;&ctx;
  1. Add Preprocessing

Alternative 9: 3.8% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \pi \cdot 0.5 + 2 \cdot \sin^{-1} \left(\sqrt{0.5 + x \cdot -0.5}\right) \end{array} \]
(FPCore (x)
 :precision binary64
 (+ (* PI 0.5) (* 2.0 (asin (sqrt (+ 0.5 (* x -0.5)))))))
double code(double x) {
	return (((double) M_PI) * 0.5) + (2.0 * asin(sqrt((0.5 + (x * -0.5)))));
}
public static double code(double x) {
	return (Math.PI * 0.5) + (2.0 * Math.asin(Math.sqrt((0.5 + (x * -0.5)))));
}
def code(x):
	return (math.pi * 0.5) + (2.0 * math.asin(math.sqrt((0.5 + (x * -0.5)))))
function code(x)
	return Float64(Float64(pi * 0.5) + Float64(2.0 * asin(sqrt(Float64(0.5 + Float64(x * -0.5))))))
end
function tmp = code(x)
	tmp = (pi * 0.5) + (2.0 * asin(sqrt((0.5 + (x * -0.5)))));
end
code[x_] := N[(N[(Pi * 0.5), $MachinePrecision] + N[(2.0 * N[ArcSin[N[Sqrt[N[(0.5 + N[(x * -0.5), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\pi \cdot 0.5 + 2 \cdot \sin^{-1} \left(\sqrt{0.5 + x \cdot -0.5}\right)
\end{array}
Derivation
    &prev;&pcontext;&pcontext2;&ctx;
  1. Add Preprocessing

Alternative 10: 6.7% accurate, 1.0× speedup?

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

\\
\frac{\pi}{2} - 2 \cdot \sin^{-1} \left(\sqrt{\frac{1 - x}{2}}\right)
\end{array}
Derivation
    &prev;&pcontext;&pcontext2;&ctx;
  1. Add Preprocessing

Developer target: 100.0% accurate, 3.1× speedup?

\[\begin{array}{l} \\ \sin^{-1} x \end{array} \]
(FPCore (x) :precision binary64 (asin x))
double code(double x) {
	return asin(x);
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = asin(x)
end function
public static double code(double x) {
	return Math.asin(x);
}
def code(x):
	return math.asin(x)
function code(x)
	return asin(x)
end
function tmp = code(x)
	tmp = asin(x);
end
code[x_] := N[ArcSin[x], $MachinePrecision]
\begin{array}{l}

\\
\sin^{-1} x
\end{array}

Reproduce

?
herbie shell --seed 2024003 
(FPCore (x)
  :name "Ian Simplification"
  :precision binary64

  :herbie-target
  (asin x)

  (- (/ PI 2.0) (* 2.0 (asin (sqrt (/ (- 1.0 x) 2.0))))))