
(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 14 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 (+ (/ (* (exp (/ (- r) (* 3.0 s))) 0.75) (* (* (* 6.0 (PI)) s) r)) (/ (* (exp (/ (- r) s)) 0.25) (* (* s r) (* 2.0 (PI))))))
\begin{array}{l}
\\
\frac{e^{\frac{-r}{3 \cdot s}} \cdot 0.75}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r} + \frac{e^{\frac{-r}{s}} \cdot 0.25}{\left(s \cdot r\right) \cdot \left(2 \cdot \mathsf{PI}\left(\right)\right)}
\end{array}
Initial program 99.6%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-*.f32N/A
lift-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-*.f3299.7
Applied rewrites99.7%
Final simplification99.7%
(FPCore (s r)
:precision binary32
(if (<=
(+
(/ (* (exp (/ (- r) s)) 0.25) (* (* (* 2.0 (PI)) s) r))
(/ (* (exp (/ (- r) (* 3.0 s))) 0.75) (* (* (* 6.0 (PI)) s) r)))
0.0)
(fma
0.25
(/ (/ (/ 1.0 (PI)) r) s)
(/
(/
(/
(/
(/
(fma
(* r r)
-0.021604938271604937
(* (fma 0.06944444444444445 r (* -0.16666666666666666 s)) s))
s)
s)
(PI))
s)
s))
(/
(-
(/
(-
(/ -0.16666666666666666 (PI))
(/ (* (/ -0.06944444444444445 (PI)) r) s))
s)
(/ -0.25 (* (PI) r)))
s)))\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\frac{e^{\frac{-r}{s}} \cdot 0.25}{\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r} + \frac{e^{\frac{-r}{3 \cdot s}} \cdot 0.75}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r} \leq 0:\\
\;\;\;\;\mathsf{fma}\left(0.25, \frac{\frac{\frac{1}{\mathsf{PI}\left(\right)}}{r}}{s}, \frac{\frac{\frac{\frac{\frac{\mathsf{fma}\left(r \cdot r, -0.021604938271604937, \mathsf{fma}\left(0.06944444444444445, r, -0.16666666666666666 \cdot s\right) \cdot s\right)}{s}}{s}}{\mathsf{PI}\left(\right)}}{s}}{s}\right)\\
\mathbf{else}:\\
\;\;\;\;\frac{\frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{\frac{-0.06944444444444445}{\mathsf{PI}\left(\right)} \cdot r}{s}}{s} - \frac{-0.25}{\mathsf{PI}\left(\right) \cdot r}}{s}\\
\end{array}
\end{array}
if (+.f32 (/.f32 (*.f32 #s(literal 1/4 binary32) (exp.f32 (/.f32 (neg.f32 r) s))) (*.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) s) r)) (/.f32 (*.f32 #s(literal 3/4 binary32) (exp.f32 (/.f32 (neg.f32 r) (*.f32 #s(literal 3 binary32) s)))) (*.f32 (*.f32 (*.f32 #s(literal 6 binary32) (PI.f32)) s) r))) < 0.0Initial program 100.0%
Taylor expanded in s around -inf
Applied rewrites3.4%
Applied rewrites6.0%
Applied rewrites13.9%
Taylor expanded in s around 0
Applied rewrites53.2%
if 0.0 < (+.f32 (/.f32 (*.f32 #s(literal 1/4 binary32) (exp.f32 (/.f32 (neg.f32 r) s))) (*.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) s) r)) (/.f32 (*.f32 #s(literal 3/4 binary32) (exp.f32 (/.f32 (neg.f32 r) (*.f32 #s(literal 3 binary32) s)))) (*.f32 (*.f32 (*.f32 #s(literal 6 binary32) (PI.f32)) s) r))) Initial program 96.9%
Taylor expanded in s around -inf
Applied rewrites57.2%
Taylor expanded in s around inf
Applied rewrites59.0%
Final simplification51.4%
(FPCore (s r) :precision binary32 (+ (/ (* (exp (/ r (* -3.0 s))) 0.75) (* (* 6.0 (PI)) (* s r))) (/ (* (exp (/ (- r) s)) 0.25) (* (* (* 2.0 (PI)) s) r))))
\begin{array}{l}
\\
\frac{e^{\frac{r}{-3 \cdot s}} \cdot 0.75}{\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot \left(s \cdot r\right)} + \frac{e^{\frac{-r}{s}} \cdot 0.25}{\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}
\end{array}
Initial program 99.6%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
lower-*.f3299.6
Applied rewrites99.6%
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
lower-*.f32N/A
metadata-eval99.6
Applied rewrites99.6%
lift-*.f32N/A
lift-*.f32N/A
associate-*r*N/A
lift-*.f32N/A
associate-*l*N/A
lift-*.f32N/A
associate-*r*N/A
*-commutativeN/A
associate-*r*N/A
*-commutativeN/A
lower-*.f32N/A
lower-*.f3299.6
Applied rewrites99.6%
Final simplification99.6%
(FPCore (s r) :precision binary32 (+ (/ (* (exp (/ r (* -3.0 s))) 0.75) (* (* (PI) s) (* 6.0 r))) (/ (* (exp (/ (- r) s)) 0.25) (* (* (* 2.0 (PI)) s) r))))
\begin{array}{l}
\\
\frac{e^{\frac{r}{-3 \cdot s}} \cdot 0.75}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot \left(6 \cdot r\right)} + \frac{e^{\frac{-r}{s}} \cdot 0.25}{\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}
\end{array}
Initial program 99.6%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
lower-*.f3299.6
Applied rewrites99.6%
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
lower-*.f32N/A
metadata-eval99.6
Applied rewrites99.6%
Final simplification99.6%
(FPCore (s r) :precision binary32 (+ (* (/ 0.25 (* (* (* 2.0 (PI)) s) r)) (exp (/ (- r) s))) (/ (* (exp (/ r (* -3.0 s))) 0.75) (* (* (PI) s) (* 6.0 r)))))
\begin{array}{l}
\\
\frac{0.25}{\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r} \cdot e^{\frac{-r}{s}} + \frac{e^{\frac{r}{-3 \cdot s}} \cdot 0.75}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot \left(6 \cdot r\right)}
\end{array}
Initial program 99.6%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
lower-*.f3299.6
Applied rewrites99.6%
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
lower-*.f32N/A
metadata-eval99.6
Applied rewrites99.6%
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
associate-/l*N/A
lower-*.f32N/A
lower-/.f3297.7
lift-*.f32N/A
*-commutativeN/A
lower-*.f3297.7
Applied rewrites97.7%
Final simplification97.7%
(FPCore (s r)
:precision binary32
(/
(-
(/
(- (/ -0.16666666666666666 (PI)) (/ (* (/ -0.06944444444444445 (PI)) r) s))
s)
(/ -0.25 (* (PI) r)))
s))\begin{array}{l}
\\
\frac{\frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{\frac{-0.06944444444444445}{\mathsf{PI}\left(\right)} \cdot r}{s}}{s} - \frac{-0.25}{\mathsf{PI}\left(\right) \cdot r}}{s}
\end{array}
Initial program 99.6%
Taylor expanded in s around -inf
Applied rewrites9.9%
Taylor expanded in s around inf
Applied rewrites10.2%
Final simplification10.2%
(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{\frac{0.16666666666666666}{\mathsf{PI}\left(\right)}}{s}}{s}
\end{array}
Initial program 99.6%
Taylor expanded in s around inf
associate-/l/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.f329.1
Applied rewrites9.1%
Taylor expanded in s around inf
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
Applied rewrites9.3%
(FPCore (s r) :precision binary32 (/ (- (/ -0.16666666666666666 (* (PI) s)) (/ -0.25 (* (PI) r))) s))
\begin{array}{l}
\\
\frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right) \cdot s} - \frac{-0.25}{\mathsf{PI}\left(\right) \cdot r}}{s}
\end{array}
Initial program 99.6%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites9.3%
(FPCore (s r) :precision binary32 (/ (/ 1.0 (/ s (/ 0.25 (PI)))) r))
\begin{array}{l}
\\
\frac{\frac{1}{\frac{s}{\frac{0.25}{\mathsf{PI}\left(\right)}}}}{r}
\end{array}
Initial program 99.6%
Taylor expanded in s around inf
associate-/l/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.f329.1
Applied rewrites9.1%
Applied rewrites9.1%
(FPCore (s r) :precision binary32 (/ 0.25 (* (/ s (/ 1.0 (PI))) r)))
\begin{array}{l}
\\
\frac{0.25}{\frac{s}{\frac{1}{\mathsf{PI}\left(\right)}} \cdot r}
\end{array}
Initial program 99.6%
Taylor expanded in s around inf
associate-/l/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.f329.1
Applied rewrites9.1%
Applied rewrites9.1%
Applied rewrites9.1%
Applied rewrites9.1%
(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
associate-/l/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.f329.1
Applied rewrites9.1%
(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 99.6%
Taylor expanded in s around inf
associate-/l/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.f329.1
Applied rewrites9.1%
Applied rewrites9.1%
Applied rewrites9.1%
(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 99.6%
Taylor expanded in s around inf
associate-/l/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.f329.1
Applied rewrites9.1%
Applied rewrites9.1%
Applied rewrites9.1%
(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
associate-/l/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.f329.1
Applied rewrites9.1%
Applied rewrites9.1%
Applied rewrites9.1%
herbie shell --seed 2024271
(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))))