
(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 16 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)) (* (* (* 6.0 (PI)) s) r)) 0.75 (* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r)))))
\begin{array}{l}
\\
\mathsf{fma}\left(\frac{e^{\frac{\frac{r}{-3}}{s}}}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}, 0.75, 0.125 \cdot \frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r}\right)
\end{array}
Initial program 99.6%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites99.7%
(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 99.6%
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-*.f3299.6
Applied rewrites99.6%
lift-/.f32N/A
lift-neg.f32N/A
distribute-frac-negN/A
distribute-neg-frac2N/A
lower-/.f32N/A
lift-*.f32N/A
distribute-lft-neg-inN/A
lower-*.f32N/A
metadata-eval99.6
Applied rewrites99.6%
(FPCore (s r)
:precision binary32
(let* ((t_0 (* (* (PI) s) r)))
(fma
0.125
(/ (exp (/ (/ r -3.0) s)) t_0)
(* 0.125 (/ (exp (/ (- r) s)) t_0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r\\
\mathsf{fma}\left(0.125, \frac{e^{\frac{\frac{r}{-3}}{s}}}{t\_0}, 0.125 \cdot \frac{e^{\frac{-r}{s}}}{t\_0}\right)
\end{array}
\end{array}
Initial program 99.6%
lift-+.f32N/A
+-commutativeN/A
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
metadata-evalN/A
metadata-evalN/A
Applied rewrites99.6%
(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 99.6%
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 rewrites99.5%
(FPCore (s r)
:precision binary32
(+
(/ (* 0.25 (exp (/ (- r) s))) (* (* (* 2.0 (PI)) s) r))
(/
(+
(/ 0.125 (* (PI) r))
(/ (/ (fma (/ r s) 0.006944444444444444 -0.041666666666666664) (PI)) s))
s)))\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{\frac{0.125}{\mathsf{PI}\left(\right) \cdot r} + \frac{\frac{\mathsf{fma}\left(\frac{r}{s}, 0.006944444444444444, -0.041666666666666664\right)}{\mathsf{PI}\left(\right)}}{s}}{s}
\end{array}
Initial program 99.6%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites11.5%
(FPCore (s r) :precision binary32 (fma (/ (fma (/ (fma 0.05555555555555555 (/ r s) -0.3333333333333333) s) r 1.0) (* (* (* 6.0 (PI)) s) r)) 0.75 (* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r)))))
\begin{array}{l}
\\
\mathsf{fma}\left(\frac{\mathsf{fma}\left(\frac{\mathsf{fma}\left(0.05555555555555555, \frac{r}{s}, -0.3333333333333333\right)}{s}, r, 1\right)}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}, 0.75, 0.125 \cdot \frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r}\right)
\end{array}
Initial program 99.6%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites99.7%
Taylor expanded in r around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
metadata-evalN/A
fp-cancel-sign-sub-invN/A
associate-*r/N/A
unpow2N/A
associate-/r*N/A
associate-*r/N/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-/.f3211.5
Applied rewrites11.5%
(FPCore (s r)
:precision binary32
(let* ((t_0 (* (PI) s)))
(fma
(+
(/ 0.16666666666666666 r)
(/ (fma 0.009259259259259259 (/ r s) -0.05555555555555555) s))
(/ 0.75 t_0)
(* 0.125 (/ (exp (/ (- r) s)) (* t_0 r))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \mathsf{PI}\left(\right) \cdot s\\
\mathsf{fma}\left(\frac{0.16666666666666666}{r} + \frac{\mathsf{fma}\left(0.009259259259259259, \frac{r}{s}, -0.05555555555555555\right)}{s}, \frac{0.75}{t\_0}, 0.125 \cdot \frac{e^{\frac{-r}{s}}}{t\_0 \cdot r}\right)
\end{array}
\end{array}
Initial program 99.6%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-*r*N/A
times-fracN/A
Applied rewrites99.6%
Taylor expanded in s around inf
+-commutativeN/A
associate--l+N/A
lower-+.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
fp-cancel-sub-sign-invN/A
associate-*r/N/A
unpow2N/A
associate-/r*N/A
metadata-evalN/A
associate-*r/N/A
metadata-evalN/A
div-add-revN/A
lower-/.f32N/A
associate-*r/N/A
lower-fma.f32N/A
lower-/.f3211.4
Applied rewrites11.4%
(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 99.6%
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-*.f3299.6
Applied rewrites99.6%
Taylor expanded in r around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
fp-cancel-sub-sign-invN/A
unpow2N/A
associate-/r*N/A
associate-/l*N/A
metadata-evalN/A
associate-*r/N/A
metadata-evalN/A
div-add-revN/A
lower-/.f32N/A
lower-fma.f32N/A
lower-/.f3211.4
Applied rewrites11.4%
(FPCore (s r)
:precision binary32
(/
(+
(/
(- (/ (* 0.06944444444444445 (/ r (PI))) s) (/ 0.16666666666666666 (PI)))
s)
(/ 0.25 (* (PI) r)))
s))\begin{array}{l}
\\
\frac{\frac{\frac{0.06944444444444445 \cdot \frac{r}{\mathsf{PI}\left(\right)}}{s} - \frac{0.16666666666666666}{\mathsf{PI}\left(\right)}}{s} + \frac{0.25}{\mathsf{PI}\left(\right) \cdot r}}{s}
\end{array}
Initial program 99.6%
Taylor expanded in s around -inf
mul-1-negN/A
distribute-neg-frac2N/A
lower-/.f32N/A
Applied rewrites11.1%
Final simplification11.1%
(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 99.6%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites11.1%
(FPCore (s r) :precision binary32 (/ (/ (fma (/ (/ r s) s) -0.16666666666666666 (/ 0.25 s)) (PI)) r))
\begin{array}{l}
\\
\frac{\frac{\mathsf{fma}\left(\frac{\frac{r}{s}}{s}, -0.16666666666666666, \frac{0.25}{s}\right)}{\mathsf{PI}\left(\right)}}{r}
\end{array}
Initial program 99.6%
Taylor expanded in r around 0
lower-/.f32N/A
Applied rewrites10.3%
(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 99.6%
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.f3210.3
Applied rewrites10.3%
(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 99.6%
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.f3210.1
Applied rewrites10.1%
Applied rewrites10.1%
(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 99.6%
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.f3210.1
Applied rewrites10.1%
(FPCore (s r) :precision binary32 (/ (/ 0.25 r) (* (PI) s)))
\begin{array}{l}
\\
\frac{\frac{0.25}{r}}{\mathsf{PI}\left(\right) \cdot s}
\end{array}
Initial program 99.6%
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.f3210.1
Applied rewrites10.1%
Applied rewrites10.1%
(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 99.6%
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.f3210.1
Applied rewrites10.1%
Applied rewrites10.1%
Applied rewrites10.1%
herbie shell --seed 2024360
(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))))