
(FPCore (x)
:precision binary64
(let* ((t_0 (/ 1.0 (fabs x)))
(t_1 (* (* t_0 t_0) t_0))
(t_2 (* (* t_1 t_0) t_0)))
(*
(* (/ 1.0 (sqrt PI)) (exp (* (fabs x) (fabs x))))
(+
(+ (+ t_0 (* (/ 1.0 2.0) t_1)) (* (/ 3.0 4.0) t_2))
(* (/ 15.0 8.0) (* (* t_2 t_0) t_0))))))
double code(double x) {
double t_0 = 1.0 / fabs(x);
double t_1 = (t_0 * t_0) * t_0;
double t_2 = (t_1 * t_0) * t_0;
return ((1.0 / sqrt(((double) M_PI))) * exp((fabs(x) * fabs(x)))) * (((t_0 + ((1.0 / 2.0) * t_1)) + ((3.0 / 4.0) * t_2)) + ((15.0 / 8.0) * ((t_2 * t_0) * t_0)));
}
public static double code(double x) {
double t_0 = 1.0 / Math.abs(x);
double t_1 = (t_0 * t_0) * t_0;
double t_2 = (t_1 * t_0) * t_0;
return ((1.0 / Math.sqrt(Math.PI)) * Math.exp((Math.abs(x) * Math.abs(x)))) * (((t_0 + ((1.0 / 2.0) * t_1)) + ((3.0 / 4.0) * t_2)) + ((15.0 / 8.0) * ((t_2 * t_0) * t_0)));
}
def code(x): t_0 = 1.0 / math.fabs(x) t_1 = (t_0 * t_0) * t_0 t_2 = (t_1 * t_0) * t_0 return ((1.0 / math.sqrt(math.pi)) * math.exp((math.fabs(x) * math.fabs(x)))) * (((t_0 + ((1.0 / 2.0) * t_1)) + ((3.0 / 4.0) * t_2)) + ((15.0 / 8.0) * ((t_2 * t_0) * t_0)))
function code(x) t_0 = Float64(1.0 / abs(x)) t_1 = Float64(Float64(t_0 * t_0) * t_0) t_2 = Float64(Float64(t_1 * t_0) * t_0) return Float64(Float64(Float64(1.0 / sqrt(pi)) * exp(Float64(abs(x) * abs(x)))) * Float64(Float64(Float64(t_0 + Float64(Float64(1.0 / 2.0) * t_1)) + Float64(Float64(3.0 / 4.0) * t_2)) + Float64(Float64(15.0 / 8.0) * Float64(Float64(t_2 * t_0) * t_0)))) end
function tmp = code(x) t_0 = 1.0 / abs(x); t_1 = (t_0 * t_0) * t_0; t_2 = (t_1 * t_0) * t_0; tmp = ((1.0 / sqrt(pi)) * exp((abs(x) * abs(x)))) * (((t_0 + ((1.0 / 2.0) * t_1)) + ((3.0 / 4.0) * t_2)) + ((15.0 / 8.0) * ((t_2 * t_0) * t_0))); end
code[x_] := Block[{t$95$0 = N[(1.0 / N[Abs[x], $MachinePrecision]), $MachinePrecision]}, Block[{t$95$1 = N[(N[(t$95$0 * t$95$0), $MachinePrecision] * t$95$0), $MachinePrecision]}, Block[{t$95$2 = N[(N[(t$95$1 * t$95$0), $MachinePrecision] * t$95$0), $MachinePrecision]}, N[(N[(N[(1.0 / N[Sqrt[Pi], $MachinePrecision]), $MachinePrecision] * N[Exp[N[(N[Abs[x], $MachinePrecision] * N[Abs[x], $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * N[(N[(N[(t$95$0 + N[(N[(1.0 / 2.0), $MachinePrecision] * t$95$1), $MachinePrecision]), $MachinePrecision] + N[(N[(3.0 / 4.0), $MachinePrecision] * t$95$2), $MachinePrecision]), $MachinePrecision] + N[(N[(15.0 / 8.0), $MachinePrecision] * N[(N[(t$95$2 * t$95$0), $MachinePrecision] * t$95$0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{\left|x\right|}\\
t_1 := \left(t\_0 \cdot t\_0\right) \cdot t\_0\\
t_2 := \left(t\_1 \cdot t\_0\right) \cdot t\_0\\
\left(\frac{1}{\sqrt{\pi}} \cdot e^{\left|x\right| \cdot \left|x\right|}\right) \cdot \left(\left(\left(t\_0 + \frac{1}{2} \cdot t\_1\right) + \frac{3}{4} \cdot t\_2\right) + \frac{15}{8} \cdot \left(\left(t\_2 \cdot t\_0\right) \cdot t\_0\right)\right)
\end{array}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 9 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (x)
:precision binary64
(let* ((t_0 (/ 1.0 (fabs x)))
(t_1 (* (* t_0 t_0) t_0))
(t_2 (* (* t_1 t_0) t_0)))
(*
(* (/ 1.0 (sqrt PI)) (exp (* (fabs x) (fabs x))))
(+
(+ (+ t_0 (* (/ 1.0 2.0) t_1)) (* (/ 3.0 4.0) t_2))
(* (/ 15.0 8.0) (* (* t_2 t_0) t_0))))))
double code(double x) {
double t_0 = 1.0 / fabs(x);
double t_1 = (t_0 * t_0) * t_0;
double t_2 = (t_1 * t_0) * t_0;
return ((1.0 / sqrt(((double) M_PI))) * exp((fabs(x) * fabs(x)))) * (((t_0 + ((1.0 / 2.0) * t_1)) + ((3.0 / 4.0) * t_2)) + ((15.0 / 8.0) * ((t_2 * t_0) * t_0)));
}
public static double code(double x) {
double t_0 = 1.0 / Math.abs(x);
double t_1 = (t_0 * t_0) * t_0;
double t_2 = (t_1 * t_0) * t_0;
return ((1.0 / Math.sqrt(Math.PI)) * Math.exp((Math.abs(x) * Math.abs(x)))) * (((t_0 + ((1.0 / 2.0) * t_1)) + ((3.0 / 4.0) * t_2)) + ((15.0 / 8.0) * ((t_2 * t_0) * t_0)));
}
def code(x): t_0 = 1.0 / math.fabs(x) t_1 = (t_0 * t_0) * t_0 t_2 = (t_1 * t_0) * t_0 return ((1.0 / math.sqrt(math.pi)) * math.exp((math.fabs(x) * math.fabs(x)))) * (((t_0 + ((1.0 / 2.0) * t_1)) + ((3.0 / 4.0) * t_2)) + ((15.0 / 8.0) * ((t_2 * t_0) * t_0)))
function code(x) t_0 = Float64(1.0 / abs(x)) t_1 = Float64(Float64(t_0 * t_0) * t_0) t_2 = Float64(Float64(t_1 * t_0) * t_0) return Float64(Float64(Float64(1.0 / sqrt(pi)) * exp(Float64(abs(x) * abs(x)))) * Float64(Float64(Float64(t_0 + Float64(Float64(1.0 / 2.0) * t_1)) + Float64(Float64(3.0 / 4.0) * t_2)) + Float64(Float64(15.0 / 8.0) * Float64(Float64(t_2 * t_0) * t_0)))) end
function tmp = code(x) t_0 = 1.0 / abs(x); t_1 = (t_0 * t_0) * t_0; t_2 = (t_1 * t_0) * t_0; tmp = ((1.0 / sqrt(pi)) * exp((abs(x) * abs(x)))) * (((t_0 + ((1.0 / 2.0) * t_1)) + ((3.0 / 4.0) * t_2)) + ((15.0 / 8.0) * ((t_2 * t_0) * t_0))); end
code[x_] := Block[{t$95$0 = N[(1.0 / N[Abs[x], $MachinePrecision]), $MachinePrecision]}, Block[{t$95$1 = N[(N[(t$95$0 * t$95$0), $MachinePrecision] * t$95$0), $MachinePrecision]}, Block[{t$95$2 = N[(N[(t$95$1 * t$95$0), $MachinePrecision] * t$95$0), $MachinePrecision]}, N[(N[(N[(1.0 / N[Sqrt[Pi], $MachinePrecision]), $MachinePrecision] * N[Exp[N[(N[Abs[x], $MachinePrecision] * N[Abs[x], $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * N[(N[(N[(t$95$0 + N[(N[(1.0 / 2.0), $MachinePrecision] * t$95$1), $MachinePrecision]), $MachinePrecision] + N[(N[(3.0 / 4.0), $MachinePrecision] * t$95$2), $MachinePrecision]), $MachinePrecision] + N[(N[(15.0 / 8.0), $MachinePrecision] * N[(N[(t$95$2 * t$95$0), $MachinePrecision] * t$95$0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{\left|x\right|}\\
t_1 := \left(t\_0 \cdot t\_0\right) \cdot t\_0\\
t_2 := \left(t\_1 \cdot t\_0\right) \cdot t\_0\\
\left(\frac{1}{\sqrt{\pi}} \cdot e^{\left|x\right| \cdot \left|x\right|}\right) \cdot \left(\left(\left(t\_0 + \frac{1}{2} \cdot t\_1\right) + \frac{3}{4} \cdot t\_2\right) + \frac{15}{8} \cdot \left(\left(t\_2 \cdot t\_0\right) \cdot t\_0\right)\right)
\end{array}
\end{array}
(FPCore (x)
:precision binary64
(let* ((t_0 (* (fabs x) (* (* x x) (* x x)))))
(*
(* (/ 1.0 (sqrt PI)) (exp (* (fabs x) (fabs x))))
(+
(/ (+ 1.0 (/ 0.5 (* x x))) (fabs x))
(+ (/ 0.75 t_0) (/ 1.875 (* (* x x) t_0)))))))
double code(double x) {
double t_0 = fabs(x) * ((x * x) * (x * x));
return ((1.0 / sqrt(((double) M_PI))) * exp((fabs(x) * fabs(x)))) * (((1.0 + (0.5 / (x * x))) / fabs(x)) + ((0.75 / t_0) + (1.875 / ((x * x) * t_0))));
}
public static double code(double x) {
double t_0 = Math.abs(x) * ((x * x) * (x * x));
return ((1.0 / Math.sqrt(Math.PI)) * Math.exp((Math.abs(x) * Math.abs(x)))) * (((1.0 + (0.5 / (x * x))) / Math.abs(x)) + ((0.75 / t_0) + (1.875 / ((x * x) * t_0))));
}
def code(x): t_0 = math.fabs(x) * ((x * x) * (x * x)) return ((1.0 / math.sqrt(math.pi)) * math.exp((math.fabs(x) * math.fabs(x)))) * (((1.0 + (0.5 / (x * x))) / math.fabs(x)) + ((0.75 / t_0) + (1.875 / ((x * x) * t_0))))
function code(x) t_0 = Float64(abs(x) * Float64(Float64(x * x) * Float64(x * x))) return Float64(Float64(Float64(1.0 / sqrt(pi)) * exp(Float64(abs(x) * abs(x)))) * Float64(Float64(Float64(1.0 + Float64(0.5 / Float64(x * x))) / abs(x)) + Float64(Float64(0.75 / t_0) + Float64(1.875 / Float64(Float64(x * x) * t_0))))) end
function tmp = code(x) t_0 = abs(x) * ((x * x) * (x * x)); tmp = ((1.0 / sqrt(pi)) * exp((abs(x) * abs(x)))) * (((1.0 + (0.5 / (x * x))) / abs(x)) + ((0.75 / t_0) + (1.875 / ((x * x) * t_0)))); end
code[x_] := Block[{t$95$0 = N[(N[Abs[x], $MachinePrecision] * N[(N[(x * x), $MachinePrecision] * N[(x * x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]}, N[(N[(N[(1.0 / N[Sqrt[Pi], $MachinePrecision]), $MachinePrecision] * N[Exp[N[(N[Abs[x], $MachinePrecision] * N[Abs[x], $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * N[(N[(N[(1.0 + N[(0.5 / N[(x * x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[Abs[x], $MachinePrecision]), $MachinePrecision] + N[(N[(0.75 / t$95$0), $MachinePrecision] + N[(1.875 / N[(N[(x * x), $MachinePrecision] * t$95$0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left|x\right| \cdot \left(\left(x \cdot x\right) \cdot \left(x \cdot x\right)\right)\\
\left(\frac{1}{\sqrt{\pi}} \cdot e^{\left|x\right| \cdot \left|x\right|}\right) \cdot \left(\frac{1 + \frac{0.5}{x \cdot x}}{\left|x\right|} + \left(\frac{0.75}{t\_0} + \frac{1.875}{\left(x \cdot x\right) \cdot t\_0}\right)\right)
\end{array}
\end{array}
Initial program 99.9%
Applied egg-rr99.9%
Final simplification99.9%
(FPCore (x)
:precision binary64
(let* ((t_0 (* x (fma (* x x) 0.16666666666666666 0.5))) (t_1 (* x t_0)))
(if (<= (fabs x) 1e+76)
(*
(fma x (/ (* x (fma t_1 t_1 -1.0)) (fma x t_0 -1.0)) 1.0)
(/ (sqrt (/ 1.0 PI)) (fabs x)))
(/ (fma x (fma x (* 0.5 (* x x)) x) 1.0) (* (sqrt PI) (fabs x))))))
double code(double x) {
double t_0 = x * fma((x * x), 0.16666666666666666, 0.5);
double t_1 = x * t_0;
double tmp;
if (fabs(x) <= 1e+76) {
tmp = fma(x, ((x * fma(t_1, t_1, -1.0)) / fma(x, t_0, -1.0)), 1.0) * (sqrt((1.0 / ((double) M_PI))) / fabs(x));
} else {
tmp = fma(x, fma(x, (0.5 * (x * x)), x), 1.0) / (sqrt(((double) M_PI)) * fabs(x));
}
return tmp;
}
function code(x) t_0 = Float64(x * fma(Float64(x * x), 0.16666666666666666, 0.5)) t_1 = Float64(x * t_0) tmp = 0.0 if (abs(x) <= 1e+76) tmp = Float64(fma(x, Float64(Float64(x * fma(t_1, t_1, -1.0)) / fma(x, t_0, -1.0)), 1.0) * Float64(sqrt(Float64(1.0 / pi)) / abs(x))); else tmp = Float64(fma(x, fma(x, Float64(0.5 * Float64(x * x)), x), 1.0) / Float64(sqrt(pi) * abs(x))); end return tmp end
code[x_] := Block[{t$95$0 = N[(x * N[(N[(x * x), $MachinePrecision] * 0.16666666666666666 + 0.5), $MachinePrecision]), $MachinePrecision]}, Block[{t$95$1 = N[(x * t$95$0), $MachinePrecision]}, If[LessEqual[N[Abs[x], $MachinePrecision], 1e+76], N[(N[(x * N[(N[(x * N[(t$95$1 * t$95$1 + -1.0), $MachinePrecision]), $MachinePrecision] / N[(x * t$95$0 + -1.0), $MachinePrecision]), $MachinePrecision] + 1.0), $MachinePrecision] * N[(N[Sqrt[N[(1.0 / Pi), $MachinePrecision]], $MachinePrecision] / N[Abs[x], $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(N[(x * N[(x * N[(0.5 * N[(x * x), $MachinePrecision]), $MachinePrecision] + x), $MachinePrecision] + 1.0), $MachinePrecision] / N[(N[Sqrt[Pi], $MachinePrecision] * N[Abs[x], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := x \cdot \mathsf{fma}\left(x \cdot x, 0.16666666666666666, 0.5\right)\\
t_1 := x \cdot t\_0\\
\mathbf{if}\;\left|x\right| \leq 10^{+76}:\\
\;\;\;\;\mathsf{fma}\left(x, \frac{x \cdot \mathsf{fma}\left(t\_1, t\_1, -1\right)}{\mathsf{fma}\left(x, t\_0, -1\right)}, 1\right) \cdot \frac{\sqrt{\frac{1}{\pi}}}{\left|x\right|}\\
\mathbf{else}:\\
\;\;\;\;\frac{\mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5 \cdot \left(x \cdot x\right), x\right), 1\right)}{\sqrt{\pi} \cdot \left|x\right|}\\
\end{array}
\end{array}
if (fabs.f64 x) < 1e76Initial program 99.9%
Applied egg-rr99.9%
Taylor expanded in x around inf
associate-*r/N/A
*-commutativeN/A
associate-/l*N/A
lower-*.f64N/A
unpow2N/A
sqr-absN/A
unpow2N/A
lower-exp.f64N/A
unpow2N/A
lower-*.f64N/A
lower-/.f64N/A
lower-sqrt.f64N/A
lower-/.f64N/A
lower-PI.f64N/A
lower-fabs.f6498.5
Simplified98.5%
Taylor expanded in x around 0
+-commutativeN/A
unpow2N/A
associate-*l*N/A
lower-fma.f64N/A
lower-*.f64N/A
+-commutativeN/A
lower-fma.f64N/A
unpow2N/A
lower-*.f64N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
unpow2N/A
lower-*.f6435.2
Simplified35.2%
lift-*.f64N/A
lift-*.f64N/A
lift-fma.f64N/A
lift-fma.f64N/A
*-commutativeN/A
lift-fma.f64N/A
flip-+N/A
associate-*l/N/A
lower-/.f64N/A
Applied egg-rr56.6%
if 1e76 < (fabs.f64 x) Initial program 100.0%
Applied egg-rr100.0%
Taylor expanded in x around inf
associate-*r/N/A
*-commutativeN/A
associate-/l*N/A
lower-*.f64N/A
unpow2N/A
sqr-absN/A
unpow2N/A
lower-exp.f64N/A
unpow2N/A
lower-*.f64N/A
lower-/.f64N/A
lower-sqrt.f64N/A
lower-/.f64N/A
lower-PI.f64N/A
lower-fabs.f64100.0
Simplified100.0%
lift-*.f64N/A
lift-exp.f64N/A
lift-PI.f64N/A
lift-/.f64N/A
lift-sqrt.f64N/A
lift-fabs.f64N/A
clear-numN/A
un-div-invN/A
*-lft-identityN/A
lift-*.f64N/A
sqr-absN/A
lift-fabs.f64N/A
lift-fabs.f64N/A
lift-*.f64N/A
lower-/.f64N/A
Applied egg-rr99.9%
Taylor expanded in x around 0
+-commutativeN/A
unpow2N/A
associate-*l*N/A
lower-fma.f64N/A
+-commutativeN/A
distribute-lft-inN/A
*-rgt-identityN/A
lower-fma.f64N/A
*-commutativeN/A
lower-*.f64N/A
unpow2N/A
lower-*.f6499.5
Simplified99.5%
Final simplification88.8%
herbie shell --seed 2024218
(FPCore (x)
:name "Jmat.Real.erfi, branch x greater than or equal to 5"
:precision binary64
:pre (>= x 0.5)
(* (* (/ 1.0 (sqrt PI)) (exp (* (fabs x) (fabs x)))) (+ (+ (+ (/ 1.0 (fabs x)) (* (/ 1.0 2.0) (* (* (/ 1.0 (fabs x)) (/ 1.0 (fabs x))) (/ 1.0 (fabs x))))) (* (/ 3.0 4.0) (* (* (* (* (/ 1.0 (fabs x)) (/ 1.0 (fabs x))) (/ 1.0 (fabs x))) (/ 1.0 (fabs x))) (/ 1.0 (fabs x))))) (* (/ 15.0 8.0) (* (* (* (* (* (* (/ 1.0 (fabs x)) (/ 1.0 (fabs x))) (/ 1.0 (fabs x))) (/ 1.0 (fabs x))) (/ 1.0 (fabs x))) (/ 1.0 (fabs x))) (/ 1.0 (fabs x)))))))