
(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 17 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
(/ 0.125 (* (PI) s))
(exp (/ (- r) s))
(*
(/ 0.125 (* (* (cbrt (* (PI) (PI))) s) (cbrt (PI))))
(exp (/ (/ r -3.0) s))))
r))\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{0.125}{\mathsf{PI}\left(\right) \cdot s}, e^{\frac{-r}{s}}, \frac{0.125}{\left(\sqrt[3]{\mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)} \cdot s\right) \cdot \sqrt[3]{\mathsf{PI}\left(\right)}} \cdot e^{\frac{\frac{r}{-3}}{s}}\right)}{r}
\end{array}
Initial program 99.7%
Applied rewrites99.6%
lift-*.f32N/A
*-commutativeN/A
lift-PI.f32N/A
add-cube-cbrtN/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
pow2N/A
lower-pow.f32N/A
lift-PI.f32N/A
lower-cbrt.f32N/A
lift-PI.f32N/A
lower-cbrt.f3299.7
Applied rewrites99.7%
Taylor expanded in s around 0
*-commutativeN/A
lower-*.f32N/A
lower-cbrt.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f3299.7
Applied rewrites99.7%
(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 99.7%
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)) (exp (/ (/ r -3.0) s)))) (* (PI) s)) r))
\begin{array}{l}
\\
\frac{\frac{0.125 \cdot \left(e^{\frac{-r}{s}} + e^{\frac{\frac{r}{-3}}{s}}\right)}{\mathsf{PI}\left(\right) \cdot s}}{r}
\end{array}
Initial program 99.7%
Applied rewrites99.6%
lift-fma.f32N/A
lift-*.f32N/A
distribute-lft-outN/A
lift-/.f32N/A
associate-*l/N/A
lower-/.f32N/A
lower-*.f32N/A
lower-+.f3299.7
Applied rewrites99.7%
(FPCore (s r) :precision binary32 (* (/ 0.125 (* (PI) s)) (/ (+ (exp (/ (- r) s)) (exp (/ (/ r -3.0) s))) r)))
\begin{array}{l}
\\
\frac{0.125}{\mathsf{PI}\left(\right) \cdot s} \cdot \frac{e^{\frac{-r}{s}} + e^{\frac{\frac{r}{-3}}{s}}}{r}
\end{array}
Initial program 99.7%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites99.7%
Applied rewrites99.7%
(FPCore (s r)
:precision binary32
(fma
(/
(-
(/
(+
(/
(fma
0.00102880658436214
(* r (/ (/ r s) (PI)))
(* -0.009259259259259259 (/ r (PI))))
s)
(/ 0.05555555555555555 (PI)))
s)
(/ 0.16666666666666666 (* (PI) r)))
(- s))
0.75
(* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r)))))\begin{array}{l}
\\
\mathsf{fma}\left(\frac{\frac{\frac{\mathsf{fma}\left(0.00102880658436214, r \cdot \frac{\frac{r}{s}}{\mathsf{PI}\left(\right)}, -0.009259259259259259 \cdot \frac{r}{\mathsf{PI}\left(\right)}\right)}{s} + \frac{0.05555555555555555}{\mathsf{PI}\left(\right)}}{s} - \frac{0.16666666666666666}{\mathsf{PI}\left(\right) \cdot r}}{-s}, 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 99.7%
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 s around -inf
Applied rewrites13.2%
Final simplification13.2%
(FPCore (s r)
:precision binary32
(fma
(/
(fma
(fma (/ 0.05555555555555555 s) (/ 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(\mathsf{fma}\left(\frac{0.05555555555555555}{s}, \frac{r}{s}, \frac{-0.3333333333333333}{s}\right), 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 99.7%
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
fp-cancel-sub-sign-invN/A
associate-*r/N/A
unpow2N/A
times-fracN/A
lower-fma.f32N/A
lower-/.f32N/A
lower-/.f32N/A
metadata-evalN/A
associate-*r/N/A
metadata-evalN/A
lower-/.f3213.1
Applied rewrites13.1%
(FPCore (s r) :precision binary32 (fma (/ (fma (/ (fma (/ 0.05555555555555555 s) r -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(\frac{0.05555555555555555}{s}, r, -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 99.7%
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
fp-cancel-sub-sign-invN/A
associate-*r/N/A
unpow2N/A
times-fracN/A
lower-fma.f32N/A
lower-/.f32N/A
lower-/.f32N/A
metadata-evalN/A
associate-*r/N/A
metadata-evalN/A
lower-/.f3213.1
Applied rewrites13.1%
Taylor expanded in s around inf
Applied rewrites13.1%
(FPCore (s r) :precision binary32 (+ (/ (fma (/ (+ -0.25 (/ (* 0.125 r) s)) s) r 0.25) (* (* (* 2.0 (PI)) s) r)) (/ (- 0.75 (/ (fma (* r (/ r s)) -0.041666666666666664 (* 0.25 r)) s)) (* (* (* 6.0 (PI)) s) r))))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{-0.25 + \frac{0.125 \cdot r}{s}}{s}, r, 0.25\right)}{\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r} + \frac{0.75 - \frac{\mathsf{fma}\left(r \cdot \frac{r}{s}, -0.041666666666666664, 0.25 \cdot r\right)}{s}}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}
\end{array}
Initial program 99.7%
Taylor expanded in r around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
fp-cancel-sub-sign-invN/A
+-commutativeN/A
metadata-evalN/A
associate-*r/N/A
metadata-evalN/A
associate-*r/N/A
unpow2N/A
associate-/r*N/A
div-add-revN/A
lower-/.f32N/A
lower-+.f32N/A
lower-/.f32N/A
lower-*.f3212.4
Applied rewrites12.4%
Taylor expanded in s around inf
associate-+r+N/A
fp-cancel-sign-sub-invN/A
associate-+l-N/A
metadata-evalN/A
associate-*r/N/A
associate-*r/N/A
unpow2N/A
associate-/r*N/A
div-subN/A
associate-/l*N/A
metadata-evalN/A
fp-cancel-sign-sub-invN/A
+-commutativeN/A
lower--.f32N/A
Applied rewrites12.4%
(FPCore (s r) :precision binary32 (/ (- (/ (fma 0.06944444444444445 (/ (/ r s) s) (/ 0.25 r)) (PI)) (/ 0.16666666666666666 (* (PI) s))) s))
\begin{array}{l}
\\
\frac{\frac{\mathsf{fma}\left(0.06944444444444445, \frac{\frac{r}{s}}{s}, \frac{0.25}{r}\right)}{\mathsf{PI}\left(\right)} - \frac{0.16666666666666666}{\mathsf{PI}\left(\right) \cdot s}}{s}
\end{array}
Initial program 99.7%
Applied rewrites99.6%
lift-*.f32N/A
*-commutativeN/A
lift-PI.f32N/A
add-cube-cbrtN/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
pow2N/A
lower-pow.f32N/A
lift-PI.f32N/A
lower-cbrt.f32N/A
lift-PI.f32N/A
lower-cbrt.f3299.7
Applied rewrites99.7%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites12.4%
Taylor expanded in s around inf
associate-/r*N/A
unpow2N/A
associate-/l/N/A
*-commutativeN/A
associate-*l/N/A
associate-*r/N/A
metadata-evalN/A
associate-/r*N/A
div-add-revN/A
lower-/.f32N/A
*-commutativeN/A
lower-fma.f32N/A
lower-/.f32N/A
lower-/.f32N/A
lower-/.f32N/A
lower-PI.f3212.4
Applied rewrites12.4%
(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 99.7%
Applied rewrites99.6%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites12.4%
Final simplification12.4%
(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 99.7%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites10.8%
(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 99.7%
Applied rewrites99.6%
Taylor expanded in s around inf
lower-/.f32N/A
lower--.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3210.8
Applied rewrites10.8%
Final simplification10.8%
(FPCore (s r) :precision binary32 (let* ((t_0 (sqrt (PI)))) (/ 0.25 (* t_0 (* t_0 (* r s))))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{\mathsf{PI}\left(\right)}\\
\frac{0.25}{t\_0 \cdot \left(t\_0 \cdot \left(r \cdot s\right)\right)}
\end{array}
\end{array}
Initial program 99.7%
Applied rewrites99.6%
Taylor expanded in s around inf
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3210.0
Applied rewrites10.0%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lift-PI.f32N/A
add-sqr-sqrtN/A
associate-*l*N/A
lower-*.f32N/A
lift-PI.f32N/A
lower-sqrt.f32N/A
lower-*.f32N/A
lift-PI.f32N/A
lower-sqrt.f32N/A
*-commutativeN/A
lower-*.f3210.0
Applied rewrites10.0%
Final simplification10.0%
(FPCore (s r) :precision binary32 (/ (/ (/ 0.25 (PI)) s) r))
\begin{array}{l}
\\
\frac{\frac{\frac{0.25}{\mathsf{PI}\left(\right)}}{s}}{r}
\end{array}
Initial program 99.7%
Applied rewrites99.6%
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
lower-PI.f3210.0
Applied rewrites10.0%
(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 99.7%
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.f3210.0
Applied rewrites10.0%
lift-/.f32N/A
lift-/.f32N/A
lift-*.f32N/A
associate-/r*N/A
associate-/l/N/A
lower-/.f32N/A
lower-/.f32N/A
lower-*.f3210.0
Applied rewrites10.0%
(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 99.7%
Applied rewrites99.6%
Taylor expanded in s around inf
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3210.0
Applied rewrites10.0%
Final simplification10.0%
(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 99.7%
Applied rewrites99.6%
Taylor expanded in s around inf
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3210.0
Applied rewrites10.0%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f3210.0
Applied rewrites10.0%
Final simplification10.0%
herbie shell --seed 2025026
(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))))