
(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 21 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 (+ (/ (* 0.25 (exp (/ (- r) s))) (* (* (* 2.0 (PI)) s) r)) (/ (* 0.75 (/ (exp (/ (/ r -3.0) s)) r)) (* (* 6.0 (PI)) 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{0.75 \cdot \frac{e^{\frac{\frac{r}{-3}}{s}}}{r}}{\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s}
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
(FPCore (s r)
:precision binary32
(let* ((t_0 (* (PI) s)))
(fma
0.125
(/ (/ (exp (/ (/ r -3.0) s)) r) 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(0.125, \frac{\frac{e^{\frac{\frac{r}{-3}}{s}}}{r}}{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
Applied rewrites99.6%
(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%
(FPCore (s r) :precision binary32 (fma 0.125 (/ (exp (/ (/ r -3.0) s)) (* (PI) (* s r))) (* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r)))))
\begin{array}{l}
\\
\mathsf{fma}\left(0.125, \frac{e^{\frac{\frac{r}{-3}}{s}}}{\mathsf{PI}\left(\right) \cdot \left(s \cdot r\right)}, 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
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lift-*.f32N/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)) 6.0) 0.75 (* 0.125 (exp (/ (- r) s)))) (* (* s r) (PI))))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{e^{\frac{\frac{r}{-3}}{s}}}{6}, 0.75, 0.125 \cdot e^{\frac{-r}{s}}\right)}{\left(s \cdot r\right) \cdot \mathsf{PI}\left(\right)}
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
Applied rewrites99.6%
(FPCore (s r) :precision binary32 (* (/ (+ (exp (/ (- r) s)) (exp (/ (/ r -3.0) s))) (* r (PI))) (/ 0.125 s)))
\begin{array}{l}
\\
\frac{e^{\frac{-r}{s}} + e^{\frac{\frac{r}{-3}}{s}}}{r \cdot \mathsf{PI}\left(\right)} \cdot \frac{0.125}{s}
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
Applied rewrites99.5%
lift-*.f32N/A
lift-/.f32N/A
associate-*l/N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lift-*.f32N/A
*-commutativeN/A
times-fracN/A
lower-*.f32N/A
lower-/.f32N/A
lower-/.f3299.6
Applied rewrites99.6%
(FPCore (s r) :precision binary32 (* (/ (+ (exp (/ (- r) s)) (exp (/ (/ r -3.0) s))) (* (* s (PI)) r)) 0.125))
\begin{array}{l}
\\
\frac{e^{\frac{-r}{s}} + e^{\frac{\frac{r}{-3}}{s}}}{\left(s \cdot \mathsf{PI}\left(\right)\right) \cdot r} \cdot 0.125
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
Applied rewrites99.5%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*l*N/A
lift-*.f32N/A
lift-*.f3299.5
lift-*.f32N/A
*-commutativeN/A
lift-*.f3299.5
Applied rewrites99.5%
(FPCore (s r) :precision binary32 (* (/ (+ (exp (/ (- r) s)) (exp (/ (/ r -3.0) s))) (* (* s r) (PI))) 0.125))
\begin{array}{l}
\\
\frac{e^{\frac{-r}{s}} + e^{\frac{\frac{r}{-3}}{s}}}{\left(s \cdot r\right) \cdot \mathsf{PI}\left(\right)} \cdot 0.125
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
Applied rewrites99.5%
(FPCore (s r) :precision binary32 (* (/ (+ (exp (/ (- r) s)) (exp (/ r (* -3.0 s)))) (* (* s r) (PI))) 0.125))
\begin{array}{l}
\\
\frac{e^{\frac{-r}{s}} + e^{\frac{r}{-3 \cdot s}}}{\left(s \cdot r\right) \cdot \mathsf{PI}\left(\right)} \cdot 0.125
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
Applied rewrites99.5%
lift-/.f32N/A
lift-/.f32N/A
associate-/l/N/A
metadata-evalN/A
distribute-lft-neg-inN/A
lower-/.f32N/A
distribute-lft-neg-inN/A
metadata-evalN/A
lower-*.f3299.5
Applied rewrites99.5%
(FPCore (s r) :precision binary32 (* (/ (+ (exp (/ (- r) s)) (exp (* -0.3333333333333333 (/ r s)))) (* (* s r) (PI))) 0.125))
\begin{array}{l}
\\
\frac{e^{\frac{-r}{s}} + e^{-0.3333333333333333 \cdot \frac{r}{s}}}{\left(s \cdot r\right) \cdot \mathsf{PI}\left(\right)} \cdot 0.125
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
Applied rewrites99.5%
Taylor expanded in s around 0
Applied rewrites99.5%
(FPCore (s r)
:precision binary32
(/
(+
(-
(fma (/ (/ r s) s) 0.006944444444444444 (/ 0.125 r))
(/ 0.041666666666666664 s))
(/ (* 0.125 (exp (/ (- r) s))) r))
(* (PI) s)))\begin{array}{l}
\\
\frac{\left(\mathsf{fma}\left(\frac{\frac{r}{s}}{s}, 0.006944444444444444, \frac{0.125}{r}\right) - \frac{0.041666666666666664}{s}\right) + \frac{0.125 \cdot e^{\frac{-r}{s}}}{r}}{\mathsf{PI}\left(\right) \cdot s}
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
Applied rewrites99.6%
Taylor expanded in s around inf
Applied rewrites9.6%
(FPCore (s r)
:precision binary32
(/
(+
(/
(-
0.125
(/
(fma (* r (/ r s)) -0.006944444444444444 (* 0.041666666666666664 r))
s))
r)
(/ (* 0.125 (exp (/ (- r) s))) r))
(* (PI) s)))\begin{array}{l}
\\
\frac{\frac{0.125 - \frac{\mathsf{fma}\left(r \cdot \frac{r}{s}, -0.006944444444444444, 0.041666666666666664 \cdot r\right)}{s}}{r} + \frac{0.125 \cdot e^{\frac{-r}{s}}}{r}}{\mathsf{PI}\left(\right) \cdot s}
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
Applied rewrites99.6%
Taylor expanded in s around inf
Applied rewrites9.6%
(FPCore (s r)
:precision binary32
(/
(+
(fma
(/ (fma -0.006944444444444444 (/ r s) 0.041666666666666664) s)
-1.0
(/ 0.125 r))
(/ (* 0.125 (exp (/ (- r) s))) r))
(* (PI) s)))\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{\mathsf{fma}\left(-0.006944444444444444, \frac{r}{s}, 0.041666666666666664\right)}{s}, -1, \frac{0.125}{r}\right) + \frac{0.125 \cdot e^{\frac{-r}{s}}}{r}}{\mathsf{PI}\left(\right) \cdot s}
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
Applied rewrites99.6%
Taylor expanded in s around -inf
Applied rewrites9.6%
(FPCore (s r) :precision binary32 (/ (- (fma 0.06944444444444445 (/ (/ r s) s) (/ 0.25 r)) (/ 0.16666666666666666 s)) (* (PI) s)))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(0.06944444444444445, \frac{\frac{r}{s}}{s}, \frac{0.25}{r}\right) - \frac{0.16666666666666666}{s}}{\mathsf{PI}\left(\right) \cdot s}
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
Applied rewrites99.6%
Taylor expanded in s around inf
Applied rewrites8.9%
(FPCore (s r) :precision binary32 (/ (fma (fma 0.06944444444444445 (/ r (* s s)) (/ -0.16666666666666666 s)) 1.0 (/ 0.25 r)) (* (PI) s)))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\mathsf{fma}\left(0.06944444444444445, \frac{r}{s \cdot s}, \frac{-0.16666666666666666}{s}\right), 1, \frac{0.25}{r}\right)}{\mathsf{PI}\left(\right) \cdot s}
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
Applied rewrites99.6%
Taylor expanded in r around 0
Applied rewrites8.9%
Applied rewrites8.9%
(FPCore (s r) :precision binary32 (/ (fma (/ (- 0.16666666666666666 (/ (* r 0.06944444444444445) s)) s) -1.0 (/ 0.25 r)) (* (PI) s)))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{0.16666666666666666 - \frac{r \cdot 0.06944444444444445}{s}}{s}, -1, \frac{0.25}{r}\right)}{\mathsf{PI}\left(\right) \cdot s}
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
Applied rewrites99.6%
Taylor expanded in s around -inf
Applied rewrites8.9%
(FPCore (s r) :precision binary32 (/ (+ (/ (fma (/ r s) 0.06944444444444445 -0.16666666666666666) s) (/ 0.25 r)) (* (PI) s)))
\begin{array}{l}
\\
\frac{\frac{\mathsf{fma}\left(\frac{r}{s}, 0.06944444444444445, -0.16666666666666666\right)}{s} + \frac{0.25}{r}}{\mathsf{PI}\left(\right) \cdot s}
\end{array}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites99.6%
Applied rewrites99.6%
Taylor expanded in r around 0
Applied rewrites8.9%
Applied rewrites8.9%
(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 99.6%
Taylor expanded in s around inf
Applied rewrites7.9%
Applied rewrites7.9%
(FPCore (s r) :precision binary32 (let* ((t_0 (sqrt (PI)))) (/ 0.25 (* (* (* r s) t_0) t_0))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{\mathsf{PI}\left(\right)}\\
\frac{0.25}{\left(\left(r \cdot s\right) \cdot t\_0\right) \cdot t\_0}
\end{array}
\end{array}
Initial program 99.6%
Taylor expanded in s around inf
Applied rewrites7.9%
Applied rewrites7.9%
Applied rewrites7.9%
(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 99.6%
Taylor expanded in s around inf
Applied rewrites7.9%
Applied rewrites7.9%
(FPCore (s r) :precision binary32 (/ 0.25 (* (* r (PI)) s)))
\begin{array}{l}
\\
\frac{0.25}{\left(r \cdot \mathsf{PI}\left(\right)\right) \cdot s}
\end{array}
Initial program 99.6%
Taylor expanded in s around inf
Applied rewrites7.9%
Applied rewrites7.9%
Applied rewrites7.9%
herbie shell --seed 2025021
(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))))