
(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 10 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 (exp (- x))))
(*
(* (/ 1.0 (sqrt (PI))) (pow (* t_0 t_0) (/ (- x) 2.0)))
(fma
(pow x -7.0)
1.875
(/ (- (/ (fma (pow x -2.0) 0.75 0.5) (* x x)) -1.0) x)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := e^{-x}\\
\left(\frac{1}{\sqrt{\mathsf{PI}\left(\right)}} \cdot {\left(t\_0 \cdot t\_0\right)}^{\left(\frac{-x}{2}\right)}\right) \cdot \mathsf{fma}\left({x}^{-7}, 1.875, \frac{\frac{\mathsf{fma}\left({x}^{-2}, 0.75, 0.5\right)}{x \cdot x} - -1}{x}\right)
\end{array}
\end{array}
Initial program 99.9%
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%
Applied rewrites100.0%
Taylor expanded in x around -inf
Applied rewrites100.0%
lift-exp.f64N/A
lift-pow.f64N/A
pow-expN/A
sqr-abs-revN/A
sqr-neg-revN/A
pow-expN/A
sqr-powN/A
pow-prod-downN/A
lower-pow.f64N/A
Applied rewrites100.0%
Final simplification100.0%
(FPCore (x) :precision binary64 (* (* (/ 1.0 (sqrt (PI))) (pow (exp (- x)) (- x))) (fma (pow x -7.0) 1.875 (/ (- (/ (fma (pow x -2.0) 0.75 0.5) (* x x)) -1.0) x))))
\begin{array}{l}
\\
\left(\frac{1}{\sqrt{\mathsf{PI}\left(\right)}} \cdot {\left(e^{-x}\right)}^{\left(-x\right)}\right) \cdot \mathsf{fma}\left({x}^{-7}, 1.875, \frac{\frac{\mathsf{fma}\left({x}^{-2}, 0.75, 0.5\right)}{x \cdot x} - -1}{x}\right)
\end{array}
Initial program 99.9%
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%
Applied rewrites100.0%
Taylor expanded in x around -inf
Applied rewrites100.0%
lift-exp.f64N/A
lift-pow.f64N/A
pow-expN/A
sqr-abs-revN/A
sqr-neg-revN/A
pow-expN/A
lower-pow.f64N/A
lower-exp.f64N/A
rem-sqrt-square-revN/A
pow2N/A
sqrt-pow1N/A
metadata-evalN/A
unpow1N/A
lower-neg.f64N/A
rem-sqrt-square-revN/A
pow2N/A
sqrt-pow1N/A
metadata-evalN/A
unpow1N/A
lower-neg.f64100.0
Applied rewrites100.0%
Final simplification100.0%
(FPCore (x) :precision binary64 (* (* (/ 1.0 (sqrt (PI))) (pow (exp x) x)) (fma (pow x -7.0) 1.875 (/ (- (/ (fma (/ 1.0 (* x x)) 0.75 0.5) (* x x)) -1.0) x))))
\begin{array}{l}
\\
\left(\frac{1}{\sqrt{\mathsf{PI}\left(\right)}} \cdot {\left(e^{x}\right)}^{x}\right) \cdot \mathsf{fma}\left({x}^{-7}, 1.875, \frac{\frac{\mathsf{fma}\left(\frac{1}{x \cdot x}, 0.75, 0.5\right)}{x \cdot x} - -1}{x}\right)
\end{array}
Initial program 99.9%
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%
Applied rewrites100.0%
Taylor expanded in x around -inf
Applied rewrites100.0%
lift-pow.f64N/A
metadata-evalN/A
pow-flipN/A
lower-/.f64N/A
pow2N/A
lift-*.f64100.0
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)) (fabs 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{\frac{0.5}{x \cdot x}}{\left|x\right|}\right) + \frac{3}{4} \cdot \left(\frac{1}{\left(x \cdot x\right) \cdot \left(x \cdot x\right)} \cdot t\_0\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 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%
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
lift-/.f64N/A
lift-fabs.f64N/A
associate-*l*N/A
frac-timesN/A
metadata-evalN/A
sqr-abs-revN/A
pow2N/A
frac-timesN/A
Applied rewrites99.9%
Final simplification99.9%
(FPCore (x) :precision binary64 (* (* (/ 1.0 (sqrt (PI))) (pow (exp x) x)) (pow x -1.0)))
\begin{array}{l}
\\
\left(\frac{1}{\sqrt{\mathsf{PI}\left(\right)}} \cdot {\left(e^{x}\right)}^{x}\right) \cdot {x}^{-1}
\end{array}
Initial program 99.9%
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%
Applied rewrites100.0%
Taylor expanded in x around -inf
Applied rewrites100.0%
Taylor expanded in x around inf
inv-powN/A
lower-pow.f6499.2
Applied rewrites99.2%
(FPCore (x)
:precision binary64
(let* ((t_0 (sqrt (PI))))
(if (<= x 1.15e+77)
(*
(* (/ 1.0 t_0) (exp (* x x)))
(/ (fma (/ (* x x) x) 0.5 (/ 0.75 x)) (pow x 4.0)))
(*
(/ (fma (fma (* x x) 0.5 1.0) (* x x) 1.0) t_0)
(/ (fma (pow x -2.0) 0.5 1.0) x)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{\mathsf{PI}\left(\right)}\\
\mathbf{if}\;x \leq 1.15 \cdot 10^{+77}:\\
\;\;\;\;\left(\frac{1}{t\_0} \cdot e^{x \cdot x}\right) \cdot \frac{\mathsf{fma}\left(\frac{x \cdot x}{x}, 0.5, \frac{0.75}{x}\right)}{{x}^{4}}\\
\mathbf{else}:\\
\;\;\;\;\frac{\mathsf{fma}\left(\mathsf{fma}\left(x \cdot x, 0.5, 1\right), x \cdot x, 1\right)}{t\_0} \cdot \frac{\mathsf{fma}\left({x}^{-2}, 0.5, 1\right)}{x}\\
\end{array}
\end{array}
if x < 1.14999999999999997e77Initial program 99.6%
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 rewrites99.6%
Taylor expanded in x around 0
lower-/.f64N/A
Applied rewrites99.6%
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
lift-/.f64N/A
lift-fabs.f64N/A
associate-*l*N/A
frac-timesN/A
metadata-evalN/A
sqr-abs-revN/A
pow2N/A
frac-timesN/A
Applied rewrites99.6%
Taylor expanded in x around 0
Applied rewrites96.3%
if 1.14999999999999997e77 < 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
pow-expN/A
sqr-abs-revN/A
sqr-neg-revN/A
lift-fabs.f64N/A
lift-neg.f64N/A
lift-fabs.f64N/A
lift-neg.f64N/A
pow-expN/A
lift-neg.f64N/A
lift-fabs.f64N/A
lift-neg.f64N/A
lift-fabs.f64N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
Applied rewrites100.0%
lift-+.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-*.f64N/A
lift-/.f64N/A
metadata-evalN/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
+-commutativeN/A
Applied rewrites32.6%
Taylor expanded in x around 0
metadata-evalN/A
div-addN/A
pow-divN/A
metadata-evalN/A
inv-powN/A
+-commutativeN/A
metadata-evalN/A
pow-plusN/A
unpow1N/A
metadata-evalN/A
sqrt-pow1N/A
pow2N/A
rem-sqrt-square-revN/A
Applied rewrites100.0%
Final simplification99.0%
(FPCore (x)
:precision binary64
(let* ((t_0 (sqrt (PI))))
(if (<= x 1e+77)
(* (* (/ 1.0 t_0) (exp (* x x))) (/ -0.5 (* (* (- x) x) x)))
(*
(/ (fma (fma (* x x) 0.5 1.0) (* x x) 1.0) t_0)
(/ (fma (pow x -2.0) 0.5 1.0) x)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{\mathsf{PI}\left(\right)}\\
\mathbf{if}\;x \leq 10^{+77}:\\
\;\;\;\;\left(\frac{1}{t\_0} \cdot e^{x \cdot x}\right) \cdot \frac{-0.5}{\left(\left(-x\right) \cdot x\right) \cdot x}\\
\mathbf{else}:\\
\;\;\;\;\frac{\mathsf{fma}\left(\mathsf{fma}\left(x \cdot x, 0.5, 1\right), x \cdot x, 1\right)}{t\_0} \cdot \frac{\mathsf{fma}\left({x}^{-2}, 0.5, 1\right)}{x}\\
\end{array}
\end{array}
if x < 9.99999999999999983e76Initial program 99.6%
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 rewrites99.6%
Taylor expanded in x around 0
Applied rewrites96.3%
lift-*.f64N/A
lift-pow.f64N/A
metadata-evalN/A
pow-flipN/A
associate-*r/N/A
unpow3N/A
pow2N/A
frac-timesN/A
frac-2negN/A
metadata-evalN/A
frac-timesN/A
metadata-evalN/A
lower-/.f64N/A
lower-*.f64N/A
lower-neg.f64N/A
pow2N/A
lift-*.f6496.3
Applied rewrites96.3%
if 9.99999999999999983e76 < 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
pow-expN/A
sqr-abs-revN/A
sqr-neg-revN/A
lift-fabs.f64N/A
lift-neg.f64N/A
lift-fabs.f64N/A
lift-neg.f64N/A
pow-expN/A
lift-neg.f64N/A
lift-fabs.f64N/A
lift-neg.f64N/A
lift-fabs.f64N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
Applied rewrites100.0%
lift-+.f64N/A
lift-/.f64N/A
lift-fabs.f64N/A
lift-*.f64N/A
lift-/.f64N/A
metadata-evalN/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
+-commutativeN/A
Applied rewrites32.6%
Taylor expanded in x around 0
metadata-evalN/A
div-addN/A
pow-divN/A
metadata-evalN/A
inv-powN/A
+-commutativeN/A
metadata-evalN/A
pow-plusN/A
unpow1N/A
metadata-evalN/A
sqrt-pow1N/A
pow2N/A
rem-sqrt-square-revN/A
Applied rewrites100.0%
Final simplification99.0%
(FPCore (x) :precision binary64 (* (* (/ 1.0 (sqrt (PI))) (exp (* x x))) (/ -0.5 (* (* (- x) x) x))))
\begin{array}{l}
\\
\left(\frac{1}{\sqrt{\mathsf{PI}\left(\right)}} \cdot e^{x \cdot x}\right) \cdot \frac{-0.5}{\left(\left(-x\right) \cdot x\right) \cdot x}
\end{array}
Initial 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 rewrites38.1%
lift-*.f64N/A
lift-pow.f64N/A
metadata-evalN/A
pow-flipN/A
associate-*r/N/A
unpow3N/A
pow2N/A
frac-timesN/A
frac-2negN/A
metadata-evalN/A
frac-timesN/A
metadata-evalN/A
lower-/.f64N/A
lower-*.f64N/A
lower-neg.f64N/A
pow2N/A
lift-*.f6435.7
Applied rewrites35.7%
Final simplification35.7%
(FPCore (x) :precision binary64 (/ (* (pow x -5.0) 0.75) (sqrt (PI))))
\begin{array}{l}
\\
\frac{{x}^{-5} \cdot 0.75}{\sqrt{\mathsf{PI}\left(\right)}}
\end{array}
Initial program 99.9%
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%
Applied rewrites100.0%
Taylor expanded in x around 0
Applied rewrites1.7%
Applied rewrites1.7%
(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 99.9%
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%
Applied rewrites100.0%
Taylor expanded in x around 0
Applied rewrites1.7%
herbie shell --seed 2025028
(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)))))))