
(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 7 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
(*
(pow (exp x) x)
(*
(+
(* (pow (fabs x) -5.0) 0.75)
(+ (* (pow (fabs x) -7.0) 1.875) (/ (+ (/ 0.5 (* x x)) 1.0) (fabs x))))
(sqrt (/ 1.0 (PI))))))\begin{array}{l}
\\
{\left(e^{x}\right)}^{x} \cdot \left(\left({\left(\left|x\right|\right)}^{-5} \cdot 0.75 + \left({\left(\left|x\right|\right)}^{-7} \cdot 1.875 + \frac{\frac{0.5}{x \cdot x} + 1}{\left|x\right|}\right)\right) \cdot \sqrt{\frac{1}{\mathsf{PI}\left(\right)}}\right)
\end{array}
Initial program 100.0%
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
lift-*.f64N/A
pow3N/A
Applied rewrites100.0%
Taylor expanded in x around 0
Applied rewrites100.0%
Applied rewrites100.0%
Applied rewrites100.0%
Final simplification100.0%
(FPCore (x)
:precision binary64
(*
(+
(* (/ 15.0 8.0) (pow (fabs x) -7.0))
(-
(/ (+ (/ 0.5 (* x x)) 1.0) (fabs x))
(* (* (/ -1.0 (* (* x x) (* x x))) (/ 1.0 (fabs x))) (/ 3.0 4.0))))
(* (exp (* (fabs x) (fabs x))) (/ 1.0 (sqrt (PI))))))\begin{array}{l}
\\
\left(\frac{15}{8} \cdot {\left(\left|x\right|\right)}^{-7} + \left(\frac{\frac{0.5}{x \cdot x} + 1}{\left|x\right|} - \left(\frac{-1}{\left(x \cdot x\right) \cdot \left(x \cdot x\right)} \cdot \frac{1}{\left|x\right|}\right) \cdot \frac{3}{4}\right)\right) \cdot \left(e^{\left|x\right| \cdot \left|x\right|} \cdot \frac{1}{\sqrt{\mathsf{PI}\left(\right)}}\right)
\end{array}
Initial program 100.0%
Taylor expanded in x around 0
+-commutativeN/A
unpow3N/A
unpow2N/A
associate-/r*N/A
associate-*r/N/A
*-lft-identityN/A
associate-*l/N/A
*-rgt-identityN/A
distribute-lft-inN/A
associate-*l/N/A
*-commutativeN/A
*-rgt-identityN/A
lower-/.f64N/A
Applied rewrites100.0%
lift-*.f64N/A
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
Applied rewrites100.0%
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
pow2N/A
lift-*.f64N/A
lift-/.f64N/A
lift-/.f64N/A
frac-timesN/A
metadata-evalN/A
lift-fabs.f64N/A
lift-fabs.f64N/A
sqr-absN/A
lift-*.f64N/A
inv-powN/A
pow-powN/A
metadata-evalN/A
metadata-evalN/A
pow-prod-upN/A
Applied rewrites100.0%
Final simplification100.0%
(FPCore (x)
:precision binary64
(let* ((t_0 (/ 1.0 (fabs x))))
(*
(-
(-
(/ (+ (/ 0.5 (* x x)) 1.0) (fabs x))
(* (* (* (/ t_0 (fabs x)) (/ -1.0 (* x x))) t_0) (/ 3.0 4.0)))
(* (* (* (* (/ -1.0 (* (* x x) (* x x))) t_0) t_0) t_0) (/ 15.0 8.0)))
(* (exp (* (fabs x) (fabs x))) (/ 1.0 (sqrt (PI)))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{\left|x\right|}\\
\left(\left(\frac{\frac{0.5}{x \cdot x} + 1}{\left|x\right|} - \left(\left(\frac{t\_0}{\left|x\right|} \cdot \frac{-1}{x \cdot x}\right) \cdot t\_0\right) \cdot \frac{3}{4}\right) - \left(\left(\left(\frac{-1}{\left(x \cdot x\right) \cdot \left(x \cdot x\right)} \cdot t\_0\right) \cdot t\_0\right) \cdot t\_0\right) \cdot \frac{15}{8}\right) \cdot \left(e^{\left|x\right| \cdot \left|x\right|} \cdot \frac{1}{\sqrt{\mathsf{PI}\left(\right)}}\right)
\end{array}
\end{array}
Initial program 100.0%
Taylor expanded in x around 0
+-commutativeN/A
unpow3N/A
unpow2N/A
associate-/r*N/A
associate-*r/N/A
*-lft-identityN/A
associate-*l/N/A
*-rgt-identityN/A
distribute-lft-inN/A
associate-*l/N/A
*-commutativeN/A
*-rgt-identityN/A
lower-/.f64N/A
Applied rewrites100.0%
lift-*.f64N/A
lift-/.f64N/A
un-div-invN/A
lift-*.f64N/A
associate-*r/N/A
lift-*.f64N/A
lift-/.f64N/A
lift-/.f64N/A
frac-timesN/A
metadata-evalN/A
lift-fabs.f64N/A
lift-fabs.f64N/A
sqr-absN/A
lift-*.f64N/A
frac-timesN/A
Applied rewrites100.0%
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
pow2N/A
lift-*.f64N/A
lift-/.f64N/A
lift-/.f64N/A
frac-timesN/A
metadata-evalN/A
lift-fabs.f64N/A
lift-fabs.f64N/A
sqr-absN/A
lift-*.f64N/A
inv-powN/A
pow-powN/A
metadata-evalN/A
metadata-evalN/A
pow-prod-upN/A
Applied rewrites100.0%
Final simplification100.0%
(FPCore (x) :precision binary64 (* (/ (/ (/ 0.5 (sqrt (PI))) (* x x)) (fabs x)) (pow (exp x) x)))
\begin{array}{l}
\\
\frac{\frac{\frac{0.5}{\sqrt{\mathsf{PI}\left(\right)}}}{x \cdot x}}{\left|x\right|} \cdot {\left(e^{x}\right)}^{x}
\end{array}
Initial program 100.0%
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
lift-*.f64N/A
pow3N/A
Applied rewrites100.0%
Taylor expanded in x around 0
Applied rewrites100.0%
Taylor expanded in x around 0
Applied rewrites32.5%
Applied rewrites34.0%
(FPCore (x) :precision binary64 (* (* (pow x -5.0) 0.75) (* (exp (* (fabs x) (fabs x))) (/ 1.0 (sqrt (PI))))))
\begin{array}{l}
\\
\left({x}^{-5} \cdot 0.75\right) \cdot \left(e^{\left|x\right| \cdot \left|x\right|} \cdot \frac{1}{\sqrt{\mathsf{PI}\left(\right)}}\right)
\end{array}
Initial program 100.0%
Taylor expanded in x around 0
+-commutativeN/A
unpow3N/A
unpow2N/A
associate-/r*N/A
associate-*r/N/A
*-lft-identityN/A
associate-*l/N/A
*-rgt-identityN/A
distribute-lft-inN/A
associate-*l/N/A
*-commutativeN/A
*-rgt-identityN/A
lower-/.f64N/A
Applied rewrites100.0%
lift-*.f64N/A
lift-/.f64N/A
un-div-invN/A
lift-*.f64N/A
associate-*r/N/A
lift-*.f64N/A
lift-/.f64N/A
lift-/.f64N/A
frac-timesN/A
metadata-evalN/A
lift-fabs.f64N/A
lift-fabs.f64N/A
sqr-absN/A
lift-*.f64N/A
frac-timesN/A
Applied rewrites100.0%
Taylor expanded in x around 0
*-commutativeN/A
cube-multN/A
sqr-absN/A
unpow2N/A
associate-*l*N/A
*-commutativeN/A
unpow2N/A
sqr-absN/A
unpow2N/A
unpow2N/A
sqr-absN/A
unpow2N/A
pow-sqrN/A
metadata-evalN/A
pow-plusN/A
metadata-evalN/A
lower-/.f64N/A
lower-pow.f64N/A
lower-fabs.f6419.2
Applied rewrites19.2%
Applied rewrites20.8%
Final simplification20.8%
(FPCore (x) :precision binary64 (/ (* (+ (/ 0.75 (pow (fabs x) 3.0)) (fma 1.5 (fabs x) (/ 0.5 (fabs x)))) (sqrt (/ 1.0 (PI)))) (* x x)))
\begin{array}{l}
\\
\frac{\left(\frac{0.75}{{\left(\left|x\right|\right)}^{3}} + \mathsf{fma}\left(1.5, \left|x\right|, \frac{0.5}{\left|x\right|}\right)\right) \cdot \sqrt{\frac{1}{\mathsf{PI}\left(\right)}}}{x \cdot x}
\end{array}
Initial program 100.0%
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
lift-*.f64N/A
pow3N/A
Applied rewrites100.0%
Taylor expanded in x around 0
Applied rewrites100.0%
Taylor expanded in x around 0
Applied rewrites2.1%
Taylor expanded in x around 0
Applied rewrites2.1%
Final simplification2.1%
(FPCore (x) :precision binary64 (/ (/ (/ 0.5 (sqrt (PI))) (fabs x)) (* x x)))
\begin{array}{l}
\\
\frac{\frac{\frac{0.5}{\sqrt{\mathsf{PI}\left(\right)}}}{\left|x\right|}}{x \cdot x}
\end{array}
Initial program 100.0%
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
lift-*.f64N/A
lift-*.f64N/A
pow3N/A
Applied rewrites100.0%
Taylor expanded in x around 0
Applied rewrites100.0%
Taylor expanded in x around 0
Applied rewrites1.8%
Applied rewrites1.8%
herbie shell --seed 2024250
(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)))))))