
(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 15 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 (+ (* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r))) (/ (* 0.75 (exp (/ r (* -3.0 s)))) (* (* (* 6.0 (PI)) s) r))))
\begin{array}{l}
\\
0.125 \cdot \frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\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}
Initial program 99.8%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-*l*N/A
times-fracN/A
lower-*.f32N/A
metadata-evalN/A
lower-/.f32N/A
lower-*.f32N/A
lower-*.f3299.8
Applied rewrites99.8%
lift-/.f32N/A
frac-2negN/A
lift-neg.f32N/A
remove-double-negN/A
lower-/.f32N/A
lift-*.f32N/A
distribute-lft-neg-inN/A
metadata-evalN/A
lower-*.f3299.8
Applied rewrites99.8%
(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 99.8%
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 rewrites99.7%
(FPCore (s r) :precision binary32 (* (/ (+ (exp (/ (/ r -3.0) s)) (exp (/ (- r) s))) (* (* (PI) s) r)) 0.125))
\begin{array}{l}
\\
\frac{e^{\frac{\frac{r}{-3}}{s}} + e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r} \cdot 0.125
\end{array}
Initial program 99.8%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-*l*N/A
times-fracN/A
lower-*.f32N/A
metadata-evalN/A
lower-/.f32N/A
lower-*.f32N/A
lower-*.f3299.8
Applied rewrites99.8%
Applied rewrites99.7%
(FPCore (s r) :precision binary32 (+ (* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r))) (/ (fma (/ (fma 0.041666666666666664 (/ r s) -0.25) s) r 0.75) (* (* (* 6.0 (PI)) s) r))))
\begin{array}{l}
\\
0.125 \cdot \frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r} + \frac{\mathsf{fma}\left(\frac{\mathsf{fma}\left(0.041666666666666664, \frac{r}{s}, -0.25\right)}{s}, r, 0.75\right)}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}
\end{array}
Initial program 99.8%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-*l*N/A
times-fracN/A
lower-*.f32N/A
metadata-evalN/A
lower-/.f32N/A
lower-*.f32N/A
lower-*.f3299.8
Applied rewrites99.8%
lift-/.f32N/A
frac-2negN/A
lift-neg.f32N/A
remove-double-negN/A
lower-/.f32N/A
lift-*.f32N/A
distribute-lft-neg-inN/A
metadata-evalN/A
lower-*.f3299.8
Applied rewrites99.8%
Taylor expanded in r around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
fp-cancel-sub-sign-invN/A
associate-*r/N/A
unpow2N/A
associate-/r*N/A
associate-*r/N/A
metadata-evalN/A
metadata-evalN/A
associate-*r/N/A
metadata-evalN/A
div-add-revN/A
lower-/.f32N/A
metadata-evalN/A
lower-fma.f32N/A
lower-/.f329.9
Applied rewrites9.9%
(FPCore (s r)
:precision binary32
(/
(/
(fma
(fma
(/ r (* (* s s) (PI)))
-0.06944444444444445
(/ (/ 0.16666666666666666 (PI)) s))
r
(/ -0.25 (PI)))
r)
(- s)))\begin{array}{l}
\\
\frac{\frac{\mathsf{fma}\left(\mathsf{fma}\left(\frac{r}{\left(s \cdot s\right) \cdot \mathsf{PI}\left(\right)}, -0.06944444444444445, \frac{\frac{0.16666666666666666}{\mathsf{PI}\left(\right)}}{s}\right), r, \frac{-0.25}{\mathsf{PI}\left(\right)}\right)}{r}}{-s}
\end{array}
Initial program 99.8%
Taylor expanded in s around -inf
Applied rewrites9.1%
Taylor expanded in r around 0
Applied rewrites9.4%
(FPCore (s r)
:precision binary32
(let* ((t_0 (* (PI) s)))
(/
(/
(fma
(/ 0.25 (PI))
t_0
(* r (fma (/ 0.06944444444444445 s) r -0.16666666666666666)))
(* t_0 r))
s)))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \mathsf{PI}\left(\right) \cdot s\\
\frac{\frac{\mathsf{fma}\left(\frac{0.25}{\mathsf{PI}\left(\right)}, t\_0, r \cdot \mathsf{fma}\left(\frac{0.06944444444444445}{s}, r, -0.16666666666666666\right)\right)}{t\_0 \cdot r}}{s}
\end{array}
\end{array}
Initial program 99.8%
Taylor expanded in s around -inf
Applied rewrites9.1%
Taylor expanded in s around inf
Applied rewrites9.4%
Applied rewrites9.4%
Applied rewrites9.4%
(FPCore (s r) :precision binary32 (+ (/ (/ (fma (/ 0.06944444444444445 s) r -0.16666666666666666) (PI)) (* s s)) (/ (/ 0.25 (* (PI) r)) s)))
\begin{array}{l}
\\
\frac{\frac{\mathsf{fma}\left(\frac{0.06944444444444445}{s}, r, -0.16666666666666666\right)}{\mathsf{PI}\left(\right)}}{s \cdot s} + \frac{\frac{0.25}{\mathsf{PI}\left(\right) \cdot r}}{s}
\end{array}
Initial program 99.8%
Taylor expanded in s around -inf
Applied rewrites9.1%
Taylor expanded in s around inf
Applied rewrites9.4%
Applied rewrites9.4%
(FPCore (s r) :precision binary32 (/ (+ (/ 0.25 (* (PI) r)) (/ (/ (+ -0.16666666666666666 (* (/ 0.06944444444444445 s) r)) (PI)) s)) s))
\begin{array}{l}
\\
\frac{\frac{0.25}{\mathsf{PI}\left(\right) \cdot r} + \frac{\frac{-0.16666666666666666 + \frac{0.06944444444444445}{s} \cdot r}{\mathsf{PI}\left(\right)}}{s}}{s}
\end{array}
Initial program 99.8%
Taylor expanded in s around -inf
Applied rewrites9.1%
Taylor expanded in s around inf
Applied rewrites9.4%
Applied rewrites9.4%
(FPCore (s r) :precision binary32 (/ (+ (/ (/ (fma (/ 0.06944444444444445 s) r -0.16666666666666666) (PI)) s) (/ 0.25 (* (PI) r))) s))
\begin{array}{l}
\\
\frac{\frac{\frac{\mathsf{fma}\left(\frac{0.06944444444444445}{s}, r, -0.16666666666666666\right)}{\mathsf{PI}\left(\right)}}{s} + \frac{0.25}{\mathsf{PI}\left(\right) \cdot r}}{s}
\end{array}
Initial program 99.8%
Taylor expanded in s around -inf
Applied rewrites9.1%
Taylor expanded in s around inf
Applied rewrites9.4%
Applied rewrites9.4%
(FPCore (s r) :precision binary32 (/ (+ (/ 0.25 (* (PI) r)) (/ (/ (fma 0.06944444444444445 r (* -0.16666666666666666 s)) (* (PI) s)) s)) s))
\begin{array}{l}
\\
\frac{\frac{0.25}{\mathsf{PI}\left(\right) \cdot r} + \frac{\frac{\mathsf{fma}\left(0.06944444444444445, r, -0.16666666666666666 \cdot s\right)}{\mathsf{PI}\left(\right) \cdot s}}{s}}{s}
\end{array}
Initial program 99.8%
Taylor expanded in s around -inf
Applied rewrites9.1%
Taylor expanded in s around inf
Applied rewrites9.4%
Taylor expanded in s around 0
Applied rewrites9.4%
(FPCore (s r) :precision binary32 (let* ((t_0 (sqrt (PI)))) (/ (/ (/ 0.25 (* s r)) t_0) t_0)))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{\mathsf{PI}\left(\right)}\\
\frac{\frac{\frac{0.25}{s \cdot r}}{t\_0}}{t\_0}
\end{array}
\end{array}
Initial program 99.8%
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.f328.6
Applied rewrites8.6%
Applied rewrites8.6%
Applied rewrites8.6%
Applied rewrites8.6%
(FPCore (s r) :precision binary32 (let* ((t_0 (sqrt (PI)))) (/ (/ 0.25 (* (* s t_0) t_0)) r)))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{\mathsf{PI}\left(\right)}\\
\frac{\frac{0.25}{\left(s \cdot t\_0\right) \cdot t\_0}}{r}
\end{array}
\end{array}
Initial program 99.8%
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.f328.6
Applied rewrites8.6%
Applied rewrites8.6%
(FPCore (s r) :precision binary32 (/ (/ 0.25 s) (* (PI) r)))
\begin{array}{l}
\\
\frac{\frac{0.25}{s}}{\mathsf{PI}\left(\right) \cdot r}
\end{array}
Initial program 99.8%
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.f328.6
Applied rewrites8.6%
Applied rewrites8.6%
Applied rewrites8.6%
Applied rewrites8.6%
(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 99.8%
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.f328.6
Applied rewrites8.6%
Applied rewrites8.6%
Applied rewrites8.6%
(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 99.8%
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.f328.6
Applied rewrites8.6%
Applied rewrites8.6%
Applied rewrites8.6%
herbie shell --seed 2025016
(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))))