
(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))))))\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{\mathsf{PI}\left(\right)}} \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 8 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))))))\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{\mathsf{PI}\left(\right)}} \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 (/ 1.0 (fabs x))))
(*
(* (/ 1.0 (sqrt (PI))) (pow (exp x) x))
(+
(+
(- t_0 (/ -0.5 (* (* x x) x)))
(* (/ 3.0 4.0) (* (/ -1.0 (* (* x x) (* x x))) (- t_0))))
(* (pow x -7.0) 1.875)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{\left|x\right|}\\
\left(\frac{1}{\sqrt{\mathsf{PI}\left(\right)}} \cdot {\left(e^{x}\right)}^{x}\right) \cdot \left(\left(\left(t\_0 - \frac{-0.5}{\left(x \cdot x\right) \cdot x}\right) + \frac{3}{4} \cdot \left(\frac{-1}{\left(x \cdot x\right) \cdot \left(x \cdot x\right)} \cdot \left(-t\_0\right)\right)\right) + {x}^{-7} \cdot 1.875\right)
\end{array}
\end{array}
Initial program 100.0%
lift-exp.f64N/A
lift-*.f64N/A
lift-fabs.f64N/A
lift-fabs.f64N/A
sqr-absN/A
exp-prodN/A
lower-pow.f64N/A
lower-exp.f64100.0
Applied rewrites100.0%
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
frac-timesN/A
metadata-evalN/A
sqr-abs-revN/A
pow2N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
frac-timesN/A
metadata-evalN/A
sqr-abs-revN/A
pow2N/A
frac-2negN/A
Applied rewrites100.0%
lift-*.f64N/A
lift-/.f64N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lower-*.f64N/A
pow3N/A
cube-divN/A
metadata-evalN/A
associate-*r/N/A
sqr-powN/A
pow-prod-downN/A
sqr-abs-revN/A
pow-prod-downN/A
Applied rewrites100.0%
Taylor expanded in x around 0
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
associate-*r/N/A
*-commutativeN/A
lower-*.f64N/A
pow-flipN/A
rem-sqrt-square-revN/A
pow2N/A
sqrt-pow1N/A
metadata-evalN/A
unpow1N/A
lower-pow.f64N/A
metadata-evalN/A
metadata-eval100.0
Applied rewrites100.0%
Final simplification100.0%
(FPCore (x)
:precision binary64
(let* ((t_0 (/ 1.0 (fabs x))))
(*
(* (/ 1.0 (sqrt (PI))) (exp (* x x)))
(+
(+
(- t_0 (/ -0.5 (* (* x x) x)))
(* (/ 3.0 4.0) (* (/ -1.0 (* (* x x) (* x x))) (- t_0))))
(* (/ 15.0 8.0) (* (* (* (* (* (* t_0 t_0) t_0) t_0) t_0) t_0) t_0))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{\left|x\right|}\\
\left(\frac{1}{\sqrt{\mathsf{PI}\left(\right)}} \cdot e^{x \cdot x}\right) \cdot \left(\left(\left(t\_0 - \frac{-0.5}{\left(x \cdot x\right) \cdot x}\right) + \frac{3}{4} \cdot \left(\frac{-1}{\left(x \cdot x\right) \cdot \left(x \cdot x\right)} \cdot \left(-t\_0\right)\right)\right) + \frac{15}{8} \cdot \left(\left(\left(\left(\left(\left(t\_0 \cdot t\_0\right) \cdot t\_0\right) \cdot t\_0\right) \cdot t\_0\right) \cdot t\_0\right) \cdot t\_0\right)\right)
\end{array}
\end{array}
Initial program 100.0%
lift-exp.f64N/A
lift-*.f64N/A
lift-fabs.f64N/A
lift-fabs.f64N/A
sqr-absN/A
exp-prodN/A
lower-pow.f64N/A
lower-exp.f64100.0
Applied rewrites100.0%
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
frac-timesN/A
metadata-evalN/A
sqr-abs-revN/A
pow2N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
frac-timesN/A
metadata-evalN/A
sqr-abs-revN/A
pow2N/A
frac-2negN/A
Applied rewrites100.0%
lift-*.f64N/A
lift-/.f64N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lower-*.f64N/A
pow3N/A
cube-divN/A
metadata-evalN/A
associate-*r/N/A
sqr-powN/A
pow-prod-downN/A
sqr-abs-revN/A
pow-prod-downN/A
Applied rewrites100.0%
lift-exp.f64N/A
lift-pow.f64N/A
pow-expN/A
pow2N/A
lower-exp.f64N/A
pow2N/A
lift-*.f64100.0
Applied rewrites100.0%
Final simplification100.0%
(FPCore (x) :precision binary64 (* (* (/ 1.0 (sqrt (PI))) (exp (* x x))) (fma 0.5 (pow x -3.0) (pow x -1.0))))
\begin{array}{l}
\\
\left(\frac{1}{\sqrt{\mathsf{PI}\left(\right)}} \cdot e^{x \cdot x}\right) \cdot \mathsf{fma}\left(0.5, {x}^{-3}, {x}^{-1}\right)
\end{array}
Initial program 100.0%
lift-*.f64N/A
lift-/.f64N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
associate-*r/N/A
*-rgt-identityN/A
associate-*r/N/A
lower-/.f64N/A
Applied rewrites100.0%
lift-+.f64N/A
lift-/.f64N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
+-commutativeN/A
lift-/.f64N/A
lift-fabs.f64N/A
frac-addN/A
sqr-abs-revN/A
pow2N/A
lower-/.f64N/A
Applied rewrites46.5%
Taylor expanded in x around 0
Applied rewrites99.7%
Final simplification99.7%
(FPCore (x)
:precision binary64
(let* ((t_0 (/ 1.0 (sqrt (PI)))) (t_1 (/ 1.0 (fabs x))))
(if (<= x 5e+51)
(* (* t_0 (exp (* x x))) (* (pow x -3.0) 0.5))
(*
(*
t_0
(fma
(fma (fma 0.16666666666666666 (* x x) 0.5) (* x x) 1.0)
(* x x)
1.0))
(+
(+
(- t_1 (/ -0.5 (* (* x x) x)))
(* (/ 3.0 4.0) (* (/ -1.0 (* (* x x) (* x x))) (- t_1))))
(*
(/ 15.0 8.0)
(* (* (* (* (* (* t_1 t_1) t_1) t_1) t_1) t_1) t_1)))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{\sqrt{\mathsf{PI}\left(\right)}}\\
t_1 := \frac{1}{\left|x\right|}\\
\mathbf{if}\;x \leq 5 \cdot 10^{+51}:\\
\;\;\;\;\left(t\_0 \cdot e^{x \cdot x}\right) \cdot \left({x}^{-3} \cdot 0.5\right)\\
\mathbf{else}:\\
\;\;\;\;\left(t\_0 \cdot \mathsf{fma}\left(\mathsf{fma}\left(\mathsf{fma}\left(0.16666666666666666, x \cdot x, 0.5\right), x \cdot x, 1\right), x \cdot x, 1\right)\right) \cdot \left(\left(\left(t\_1 - \frac{-0.5}{\left(x \cdot x\right) \cdot x}\right) + \frac{3}{4} \cdot \left(\frac{-1}{\left(x \cdot x\right) \cdot \left(x \cdot x\right)} \cdot \left(-t\_1\right)\right)\right) + \frac{15}{8} \cdot \left(\left(\left(\left(\left(\left(t\_1 \cdot t\_1\right) \cdot t\_1\right) \cdot t\_1\right) \cdot t\_1\right) \cdot t\_1\right) \cdot t\_1\right)\right)\\
\end{array}
\end{array}
if x < 5e51Initial program 99.9%
lift-*.f64N/A
lift-/.f64N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
associate-*r/N/A
*-rgt-identityN/A
associate-*r/N/A
lower-/.f64N/A
Applied rewrites99.9%
Taylor expanded in x around 0
Applied rewrites97.9%
if 5e51 < x Initial program 100.0%
lift-exp.f64N/A
lift-*.f64N/A
lift-fabs.f64N/A
lift-fabs.f64N/A
sqr-absN/A
exp-prodN/A
lower-pow.f64N/A
lower-exp.f64100.0
Applied rewrites100.0%
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
frac-timesN/A
metadata-evalN/A
sqr-abs-revN/A
pow2N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
frac-timesN/A
metadata-evalN/A
sqr-abs-revN/A
pow2N/A
frac-2negN/A
Applied rewrites100.0%
lift-*.f64N/A
lift-/.f64N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lower-*.f64N/A
pow3N/A
cube-divN/A
metadata-evalN/A
associate-*r/N/A
sqr-powN/A
pow-prod-downN/A
sqr-abs-revN/A
pow-prod-downN/A
Applied rewrites100.0%
Taylor expanded in x around 0
metadata-evalN/A
pow-expN/A
sqr-abs-revN/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
Applied rewrites100.0%
Final simplification99.7%
(FPCore (x)
:precision binary64
(let* ((t_0 (/ 1.0 (fabs x))) (t_1 (sqrt (PI))))
(if (<= x 5.1e+107)
(* (* (/ 1.0 t_1) (exp (* x x))) (* (pow x -3.0) 0.5))
(*
(/ (fma x x 1.0) t_1)
(+
(+
(- t_0 (/ -0.5 (* (* x x) x)))
(* (/ 3.0 4.0) (* (* (* (* t_0 t_0) t_0) t_0) t_0)))
(* (pow x -7.0) 1.875))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{\left|x\right|}\\
t_1 := \sqrt{\mathsf{PI}\left(\right)}\\
\mathbf{if}\;x \leq 5.1 \cdot 10^{+107}:\\
\;\;\;\;\left(\frac{1}{t\_1} \cdot e^{x \cdot x}\right) \cdot \left({x}^{-3} \cdot 0.5\right)\\
\mathbf{else}:\\
\;\;\;\;\frac{\mathsf{fma}\left(x, x, 1\right)}{t\_1} \cdot \left(\left(\left(t\_0 - \frac{-0.5}{\left(x \cdot x\right) \cdot x}\right) + \frac{3}{4} \cdot \left(\left(\left(\left(t\_0 \cdot t\_0\right) \cdot t\_0\right) \cdot t\_0\right) \cdot t\_0\right)\right) + {x}^{-7} \cdot 1.875\right)\\
\end{array}
\end{array}
if x < 5.1000000000000002e107Initial program 100.0%
lift-*.f64N/A
lift-/.f64N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
associate-*r/N/A
*-rgt-identityN/A
associate-*r/N/A
lower-/.f64N/A
Applied rewrites100.0%
Taylor expanded in x around 0
Applied rewrites99.0%
if 5.1000000000000002e107 < x Initial program 100.0%
lift-*.f64N/A
lift-/.f64N/A
lift-exp.f64N/A
lift-*.f64N/A
lift-fabs.f64N/A
lift-fabs.f64N/A
pow2N/A
associate-*l/N/A
*-lft-identityN/A
lower-/.f64N/A
pow2N/A
sqr-absN/A
exp-prodN/A
lower-pow.f64N/A
lower-exp.f64100.0
Applied rewrites100.0%
Taylor expanded in x around 0
+-commutativeN/A
pow2N/A
sqr-abs-revN/A
lower-fma.f64N/A
rem-sqrt-square-revN/A
pow2N/A
sqrt-pow1N/A
metadata-evalN/A
unpow1N/A
rem-sqrt-square-revN/A
pow2N/A
sqrt-pow1N/A
metadata-evalN/A
unpow180.5
Applied rewrites80.5%
lift-*.f64N/A
lift-/.f64N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lower-*.f64N/A
pow3N/A
cube-divN/A
metadata-evalN/A
associate-*r/N/A
sqr-powN/A
pow-prod-downN/A
sqr-abs-revN/A
pow-prod-downN/A
Applied rewrites80.5%
Taylor expanded in x around 0
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
associate-*r/N/A
*-commutativeN/A
lower-*.f64N/A
pow-flipN/A
rem-sqrt-square-revN/A
pow2N/A
sqrt-pow1N/A
metadata-evalN/A
unpow1N/A
lower-pow.f64N/A
metadata-evalN/A
metadata-eval80.5
Applied rewrites80.5%
Final simplification86.6%
(FPCore (x) :precision binary64 (* (* (/ 1.0 (sqrt (PI))) (exp (* x x))) (* (pow x -3.0) 0.5)))
\begin{array}{l}
\\
\left(\frac{1}{\sqrt{\mathsf{PI}\left(\right)}} \cdot e^{x \cdot x}\right) \cdot \left({x}^{-3} \cdot 0.5\right)
\end{array}
Initial program 100.0%
lift-*.f64N/A
lift-/.f64N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
associate-*r/N/A
*-rgt-identityN/A
associate-*r/N/A
lower-/.f64N/A
Applied rewrites100.0%
Taylor expanded in x around 0
Applied rewrites32.5%
Final simplification32.5%
(FPCore (x) :precision binary64 (/ 0.5 (* (pow x 3.0) (sqrt (PI)))))
\begin{array}{l}
\\
\frac{0.5}{{x}^{3} \cdot \sqrt{\mathsf{PI}\left(\right)}}
\end{array}
Initial program 100.0%
lift-*.f64N/A
lift-/.f64N/A
lift-exp.f64N/A
lift-*.f64N/A
lift-fabs.f64N/A
lift-fabs.f64N/A
pow2N/A
associate-*l/N/A
*-lft-identityN/A
lower-/.f64N/A
pow2N/A
sqr-absN/A
exp-prodN/A
lower-pow.f64N/A
lower-exp.f64100.0
Applied rewrites100.0%
Taylor expanded in x around 0
+-commutativeN/A
pow2N/A
sqr-abs-revN/A
lower-fma.f64N/A
rem-sqrt-square-revN/A
pow2N/A
sqrt-pow1N/A
metadata-evalN/A
unpow1N/A
rem-sqrt-square-revN/A
pow2N/A
sqrt-pow1N/A
metadata-evalN/A
unpow155.3
Applied rewrites55.3%
lift-*.f64N/A
lift-/.f64N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lower-*.f64N/A
pow3N/A
cube-divN/A
metadata-evalN/A
associate-*r/N/A
sqr-powN/A
pow-prod-downN/A
sqr-abs-revN/A
pow-prod-downN/A
Applied rewrites55.3%
Taylor expanded in x around 0
metadata-evalN/A
pow-flipN/A
metadata-evalN/A
associate-*r*N/A
Applied rewrites1.8%
(FPCore (x) :precision binary64 (/ 0.75 (* (pow x 5.0) (sqrt (PI)))))
\begin{array}{l}
\\
\frac{0.75}{{x}^{5} \cdot \sqrt{\mathsf{PI}\left(\right)}}
\end{array}
Initial program 100.0%
lift-exp.f64N/A
lift-*.f64N/A
lift-fabs.f64N/A
lift-fabs.f64N/A
sqr-absN/A
exp-prodN/A
lower-pow.f64N/A
lower-exp.f64100.0
Applied rewrites100.0%
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
frac-timesN/A
metadata-evalN/A
sqr-abs-revN/A
pow2N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
frac-timesN/A
metadata-evalN/A
sqr-abs-revN/A
pow2N/A
frac-2negN/A
Applied rewrites100.0%
Taylor expanded in x around 0
Applied rewrites1.7%
herbie shell --seed 2025073
(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)))))))