
(FPCore (s r) :precision binary32 (+ (/ (* 0.25 (exp (/ (- r) s))) (* (* (* 2.0 (PI)) s) r)) (/ (* 0.75 (exp (/ (- r) (* 3.0 s)))) (* (* (* 6.0 (PI)) s) r))))
\begin{array}{l}
\\
\frac{0.25 \cdot e^{\frac{-r}{s}}}{\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r} + \frac{0.75 \cdot e^{\frac{-r}{3 \cdot s}}}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 18 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (s r) :precision binary32 (+ (/ (* 0.25 (exp (/ (- r) s))) (* (* (* 2.0 (PI)) s) r)) (/ (* 0.75 (exp (/ (- r) (* 3.0 s)))) (* (* (* 6.0 (PI)) s) r))))
\begin{array}{l}
\\
\frac{0.25 \cdot e^{\frac{-r}{s}}}{\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r} + \frac{0.75 \cdot e^{\frac{-r}{3 \cdot s}}}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}
\end{array}
(FPCore (s r) :precision binary32 (fma (/ (/ (exp (/ (/ r -3.0) s)) (* (PI) 6.0)) r) (/ 0.75 s) (* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r)))))
\begin{array}{l}
\\
\mathsf{fma}\left(\frac{\frac{e^{\frac{\frac{r}{-3}}{s}}}{\mathsf{PI}\left(\right) \cdot 6}}{r}, \frac{0.75}{s}, 0.125 \cdot \frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r}\right)
\end{array}
Initial program 99.3%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
times-fracN/A
lower-fma.f32N/A
Applied rewrites99.3%
lift-/.f32N/A
Applied rewrites99.4%
(FPCore (s r) :precision binary32 (fma (/ (exp (/ (/ r -3.0) s)) (* r (* 6.0 (PI)))) (/ 0.75 s) (* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r)))))
\begin{array}{l}
\\
\mathsf{fma}\left(\frac{e^{\frac{\frac{r}{-3}}{s}}}{r \cdot \left(6 \cdot \mathsf{PI}\left(\right)\right)}, \frac{0.75}{s}, 0.125 \cdot \frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r}\right)
\end{array}
Initial program 99.3%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
times-fracN/A
lower-fma.f32N/A
Applied rewrites99.3%
(FPCore (s r) :precision binary32 (/ (fma (/ (exp (/ (/ r -3.0) s)) (PI)) 0.125 (* (/ (exp (/ (- r) s)) (PI)) 0.125)) (* s r)))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{e^{\frac{\frac{r}{-3}}{s}}}{\mathsf{PI}\left(\right)}, 0.125, \frac{e^{\frac{-r}{s}}}{\mathsf{PI}\left(\right)} \cdot 0.125\right)}{s \cdot r}
\end{array}
Initial program 99.3%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-/r*N/A
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-/r*N/A
Applied rewrites99.3%
(FPCore (s r) :precision binary32 (/ (fma (/ (exp (/ (- r) s)) (PI)) 0.125 (* (exp (/ (/ r -3.0) s)) (/ 0.125 (PI)))) (* s r)))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{e^{\frac{-r}{s}}}{\mathsf{PI}\left(\right)}, 0.125, e^{\frac{\frac{r}{-3}}{s}} \cdot \frac{0.125}{\mathsf{PI}\left(\right)}\right)}{s \cdot r}
\end{array}
Initial program 99.3%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-/r*N/A
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-/r*N/A
Applied rewrites99.3%
lift-fma.f32N/A
+-commutativeN/A
lift-*.f32N/A
lower-fma.f32N/A
lift-/.f32N/A
associate-*l/N/A
lift-/.f32N/A
lift-/.f32N/A
frac-2negN/A
lift-neg.f32N/A
metadata-evalN/A
associate-/r*N/A
lift-*.f32N/A
lift-/.f32N/A
Applied rewrites99.3%
(FPCore (s r) :precision binary32 (/ (fma (/ (exp (/ r (* s -3.0))) (PI)) 0.125 (* (/ (exp (/ (- r) s)) (PI)) 0.125)) (* s r)))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{e^{\frac{r}{s \cdot -3}}}{\mathsf{PI}\left(\right)}, 0.125, \frac{e^{\frac{-r}{s}}}{\mathsf{PI}\left(\right)} \cdot 0.125\right)}{s \cdot r}
\end{array}
Initial program 99.3%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-/r*N/A
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-/r*N/A
Applied rewrites99.3%
lift-/.f32N/A
lift-/.f32N/A
associate-/l/N/A
metadata-evalN/A
distribute-lft-neg-inN/A
lift-*.f32N/A
lower-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
distribute-rgt-neg-inN/A
metadata-evalN/A
lower-*.f3299.3
Applied rewrites99.3%
(FPCore (s r) :precision binary32 (/ (* (/ (+ (exp (/ (/ r -3.0) s)) (exp (/ (- r) s))) (PI)) 0.125) (* s r)))
\begin{array}{l}
\\
\frac{\frac{e^{\frac{\frac{r}{-3}}{s}} + e^{\frac{-r}{s}}}{\mathsf{PI}\left(\right)} \cdot 0.125}{s \cdot r}
\end{array}
Initial program 99.3%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-/r*N/A
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-/r*N/A
Applied rewrites99.3%
Applied rewrites99.2%
(FPCore (s r)
:precision binary32
(fma
(/
(-
1.0
(/ (fma 0.3333333333333333 r (* -0.05555555555555555 (* r (/ r s)))) s))
(* r (* 6.0 (PI))))
(/ 0.75 s)
(* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r)))))\begin{array}{l}
\\
\mathsf{fma}\left(\frac{1 - \frac{\mathsf{fma}\left(0.3333333333333333, r, -0.05555555555555555 \cdot \left(r \cdot \frac{r}{s}\right)\right)}{s}}{r \cdot \left(6 \cdot \mathsf{PI}\left(\right)\right)}, \frac{0.75}{s}, 0.125 \cdot \frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r}\right)
\end{array}
Initial program 99.3%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
times-fracN/A
lower-fma.f32N/A
Applied rewrites99.3%
Taylor expanded in s around -inf
fp-cancel-sign-sub-invN/A
metadata-evalN/A
*-lft-identityN/A
lower--.f32N/A
lower-/.f32N/A
+-commutativeN/A
lower-fma.f32N/A
lower-*.f32N/A
unpow2N/A
associate-/l*N/A
lower-*.f32N/A
lower-/.f3210.8
Applied rewrites10.8%
(FPCore (s r)
:precision binary32
(/
(fma
(/
(fma
(- (* (/ r (* s s)) 0.05555555555555555) (/ 0.3333333333333333 s))
r
1.0)
(PI))
0.125
(* (/ (exp (/ (- r) s)) (PI)) 0.125))
(* s r)))\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{\mathsf{fma}\left(\frac{r}{s \cdot s} \cdot 0.05555555555555555 - \frac{0.3333333333333333}{s}, r, 1\right)}{\mathsf{PI}\left(\right)}, 0.125, \frac{e^{\frac{-r}{s}}}{\mathsf{PI}\left(\right)} \cdot 0.125\right)}{s \cdot r}
\end{array}
Initial program 99.3%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-/r*N/A
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-/r*N/A
Applied rewrites99.3%
Taylor expanded in r around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-/.f32N/A
unpow2N/A
lower-*.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f3210.8
Applied rewrites10.8%
(FPCore (s r) :precision binary32 (/ (fma (/ r (* (* s s) (PI))) 0.06944444444444445 (/ (fma -0.16666666666666666 (/ 1.0 s) (/ 0.25 r)) (PI))) s))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{r}{\left(s \cdot s\right) \cdot \mathsf{PI}\left(\right)}, 0.06944444444444445, \frac{\mathsf{fma}\left(-0.16666666666666666, \frac{1}{s}, \frac{0.25}{r}\right)}{\mathsf{PI}\left(\right)}\right)}{s}
\end{array}
Initial program 99.3%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites10.4%
(FPCore (s r) :precision binary32 (/ (- (fma (/ r (* (* s s) (PI))) 0.06944444444444445 (/ 0.25 (* (PI) r))) (/ 0.16666666666666666 (* (PI) s))) s))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{r}{\left(s \cdot s\right) \cdot \mathsf{PI}\left(\right)}, 0.06944444444444445, \frac{0.25}{\mathsf{PI}\left(\right) \cdot r}\right) - \frac{0.16666666666666666}{\mathsf{PI}\left(\right) \cdot s}}{s}
\end{array}
Initial program 99.3%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
times-fracN/A
lower-fma.f32N/A
Applied rewrites99.3%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites10.4%
(FPCore (s r) :precision binary32 (/ (/ (fma -0.16666666666666666 (/ 1.0 s) (/ 0.25 r)) (PI)) s))
\begin{array}{l}
\\
\frac{\frac{\mathsf{fma}\left(-0.16666666666666666, \frac{1}{s}, \frac{0.25}{r}\right)}{\mathsf{PI}\left(\right)}}{s}
\end{array}
Initial program 99.3%
Taylor expanded in s around inf
lower-/.f32N/A
fp-cancel-sub-sign-invN/A
+-commutativeN/A
metadata-evalN/A
associate-/r*N/A
associate-*r/N/A
associate-*r/N/A
metadata-evalN/A
associate-/r*N/A
div-add-revN/A
lower-/.f32N/A
lower-fma.f32N/A
lower-/.f32N/A
lower-/.f32N/A
lower-PI.f329.6
Applied rewrites9.6%
(FPCore (s r) :precision binary32 (/ (- (/ 0.25 (* (PI) r)) (/ 0.16666666666666666 (* (PI) s))) s))
\begin{array}{l}
\\
\frac{\frac{0.25}{\mathsf{PI}\left(\right) \cdot r} - \frac{0.16666666666666666}{\mathsf{PI}\left(\right) \cdot s}}{s}
\end{array}
Initial program 99.3%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
times-fracN/A
lower-fma.f32N/A
Applied rewrites99.3%
Taylor expanded in s around inf
lower-/.f32N/A
associate-*r/N/A
metadata-evalN/A
lower--.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f32N/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f329.5
Applied rewrites9.5%
(FPCore (s r) :precision binary32 (/ (/ (/ 0.25 s) (PI)) r))
\begin{array}{l}
\\
\frac{\frac{\frac{0.25}{s}}{\mathsf{PI}\left(\right)}}{r}
\end{array}
Initial program 99.3%
Taylor expanded in s around inf
*-commutativeN/A
associate-/r*N/A
metadata-evalN/A
associate-*r/N/A
lower-/.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f329.3
Applied rewrites9.3%
Applied rewrites9.3%
(FPCore (s r) :precision binary32 (/ (/ 0.25 (* (PI) s)) r))
\begin{array}{l}
\\
\frac{\frac{0.25}{\mathsf{PI}\left(\right) \cdot s}}{r}
\end{array}
Initial program 99.3%
Taylor expanded in s around inf
*-commutativeN/A
associate-/r*N/A
metadata-evalN/A
associate-*r/N/A
lower-/.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f329.3
Applied rewrites9.3%
(FPCore (s r) :precision binary32 (/ (/ 0.25 (PI)) (* s r)))
\begin{array}{l}
\\
\frac{\frac{0.25}{\mathsf{PI}\left(\right)}}{s \cdot r}
\end{array}
Initial program 99.3%
Taylor expanded in s around inf
*-commutativeN/A
associate-/r*N/A
metadata-evalN/A
associate-*r/N/A
lower-/.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f329.3
Applied rewrites9.3%
Applied rewrites9.3%
(FPCore (s r) :precision binary32 (/ 0.25 (* (* (PI) s) r)))
\begin{array}{l}
\\
\frac{0.25}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r}
\end{array}
Initial program 99.3%
Taylor expanded in s around inf
*-commutativeN/A
associate-/r*N/A
metadata-evalN/A
associate-*r/N/A
lower-/.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f329.3
Applied rewrites9.3%
Applied rewrites9.3%
(FPCore (s r) :precision binary32 (/ 0.25 (* (* (PI) r) s)))
\begin{array}{l}
\\
\frac{0.25}{\left(\mathsf{PI}\left(\right) \cdot r\right) \cdot s}
\end{array}
Initial program 99.3%
Taylor expanded in s around inf
*-commutativeN/A
associate-/r*N/A
metadata-evalN/A
associate-*r/N/A
lower-/.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f329.3
Applied rewrites9.3%
Applied rewrites9.3%
Applied rewrites9.3%
(FPCore (s r) :precision binary32 (/ 0.25 (* (* s r) (PI))))
\begin{array}{l}
\\
\frac{0.25}{\left(s \cdot r\right) \cdot \mathsf{PI}\left(\right)}
\end{array}
Initial program 99.3%
Taylor expanded in s around inf
*-commutativeN/A
associate-/r*N/A
metadata-evalN/A
associate-*r/N/A
lower-/.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f329.3
Applied rewrites9.3%
Applied rewrites9.3%
Applied rewrites9.3%
herbie shell --seed 2025017
(FPCore (s r)
:name "Disney BSSRDF, PDF of scattering profile"
:precision binary32
:pre (and (and (<= 0.0 s) (<= s 256.0)) (and (< 1e-6 r) (< r 1000000.0)))
(+ (/ (* 0.25 (exp (/ (- r) s))) (* (* (* 2.0 (PI)) s) r)) (/ (* 0.75 (exp (/ (- r) (* 3.0 s)))) (* (* (* 6.0 (PI)) s) r))))