
(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 19 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 (/ (exp (/ (- r) s)) (* (PI) (* s r))) (* 0.125 (/ (exp (/ (/ r -3.0) s)) (* (* (PI) r) s)))))
\begin{array}{l}
\\
\mathsf{fma}\left(0.125, \frac{e^{\frac{-r}{s}}}{\mathsf{PI}\left(\right) \cdot \left(s \cdot r\right)}, 0.125 \cdot \frac{e^{\frac{\frac{r}{-3}}{s}}}{\left(\mathsf{PI}\left(\right) \cdot r\right) \cdot s}\right)
\end{array}
Initial program 99.5%
lift-+.f32N/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
lower-fma.f32N/A
Applied rewrites99.6%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
*-commutativeN/A
lift-*.f32N/A
lower-*.f3299.6
Applied rewrites99.6%
(FPCore (s r) :precision binary32 (* (/ (+ (exp (/ (- r) s)) (exp (/ (/ r -3.0) s))) (* (* (PI) s) r)) 0.125))
\begin{array}{l}
\\
\frac{e^{\frac{-r}{s}} + e^{\frac{\frac{r}{-3}}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r} \cdot 0.125
\end{array}
Initial program 99.5%
lift-+.f32N/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
lower-fma.f32N/A
Applied rewrites99.6%
lift-fma.f32N/A
lift-*.f32N/A
distribute-lft-outN/A
*-commutativeN/A
lower-*.f32N/A
Applied rewrites99.6%
(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 99.5%
lift-+.f32N/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
lower-fma.f32N/A
Applied rewrites99.6%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
*-commutativeN/A
lift-*.f32N/A
lower-*.f3299.6
Applied rewrites99.6%
lift-fma.f32N/A
lift-*.f32N/A
distribute-lft-outN/A
*-commutativeN/A
lower-*.f32N/A
Applied rewrites99.6%
(FPCore (s r)
:precision binary32
(+
(/ (* 0.25 (exp (/ (- r) s))) (* (* (* 2.0 (PI)) s) r))
(/
(+
(/ 0.125 (* (PI) r))
(/
(/ (/ (fma -0.041666666666666664 s (* 0.006944444444444444 r)) s) (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{\frac{\mathsf{fma}\left(-0.041666666666666664, s, 0.006944444444444444 \cdot r\right)}{s}}{\mathsf{PI}\left(\right)}}{s}}{s}
\end{array}
Initial program 99.5%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites13.8%
Taylor expanded in s around 0
Applied rewrites13.8%
(FPCore (s r)
:precision binary32
(fma
(/ (exp (/ (- r) s)) (* (* (PI) s) r))
0.125
(/
(+
(/ (/ (fma 0.006944444444444444 (/ r s) -0.041666666666666664) (PI)) s)
(/ 0.125 (* (PI) r)))
s)))\begin{array}{l}
\\
\mathsf{fma}\left(\frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r}, 0.125, \frac{\frac{\frac{\mathsf{fma}\left(0.006944444444444444, \frac{r}{s}, -0.041666666666666664\right)}{\mathsf{PI}\left(\right)}}{s} + \frac{0.125}{\mathsf{PI}\left(\right) \cdot r}}{s}\right)
\end{array}
Initial program 99.5%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites13.8%
lift-+.f32N/A
Applied rewrites13.8%
(FPCore (s r)
:precision binary32
(/
(-
(/
(*
(fma (/ (fma (/ r s) 0.05555555555555555 -0.3333333333333333) s) r 1.0)
0.75)
(* 6.0 (PI)))
(* -0.125 (/ (exp (/ (- r) s)) (PI))))
(* s r)))\begin{array}{l}
\\
\frac{\frac{\mathsf{fma}\left(\frac{\mathsf{fma}\left(\frac{r}{s}, 0.05555555555555555, -0.3333333333333333\right)}{s}, r, 1\right) \cdot 0.75}{6 \cdot \mathsf{PI}\left(\right)} - -0.125 \cdot \frac{e^{\frac{-r}{s}}}{\mathsf{PI}\left(\right)}}{s \cdot r}
\end{array}
Initial program 99.5%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
times-fracN/A
lower-fma.f32N/A
Applied rewrites99.6%
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-*.f3213.7
Applied rewrites13.7%
Applied rewrites13.7%
(FPCore (s r)
:precision binary32
(/
(-
(*
(/
(fma (/ (fma (/ r s) 0.05555555555555555 -0.3333333333333333) s) r 1.0)
(* 6.0 (PI)))
0.75)
(* -0.125 (/ (exp (/ (- r) s)) (PI))))
(* s r)))\begin{array}{l}
\\
\frac{\frac{\mathsf{fma}\left(\frac{\mathsf{fma}\left(\frac{r}{s}, 0.05555555555555555, -0.3333333333333333\right)}{s}, r, 1\right)}{6 \cdot \mathsf{PI}\left(\right)} \cdot 0.75 - -0.125 \cdot \frac{e^{\frac{-r}{s}}}{\mathsf{PI}\left(\right)}}{s \cdot r}
\end{array}
Initial program 99.5%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
times-fracN/A
lower-fma.f32N/A
Applied rewrites99.6%
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-*.f3213.7
Applied rewrites13.7%
Applied rewrites13.7%
(FPCore (s r)
:precision binary32
(+
(/ (fma (/ (fma (/ r s) 0.125 -0.25) s) r 0.25) (* (* (* 2.0 (PI)) s) r))
(/
(+
(/ (/ (fma 0.006944444444444444 (/ r s) -0.041666666666666664) (PI)) s)
(/ 0.125 (* (PI) r)))
s)))\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{\mathsf{fma}\left(\frac{r}{s}, 0.125, -0.25\right)}{s}, r, 0.25\right)}{\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r} + \frac{\frac{\frac{\mathsf{fma}\left(0.006944444444444444, \frac{r}{s}, -0.041666666666666664\right)}{\mathsf{PI}\left(\right)}}{s} + \frac{0.125}{\mathsf{PI}\left(\right) \cdot r}}{s}
\end{array}
Initial program 99.5%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites13.8%
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-*.f3213.0
Applied rewrites13.0%
Applied rewrites13.0%
(FPCore (s r)
:precision binary32
(/
(+
(/
(- (* (* (/ r (PI)) 0.06944444444444445) (PI)) (* 0.16666666666666666 s))
(* (* (PI) s) s))
(/ 0.25 (* (PI) r)))
s))\begin{array}{l}
\\
\frac{\frac{\left(\frac{r}{\mathsf{PI}\left(\right)} \cdot 0.06944444444444445\right) \cdot \mathsf{PI}\left(\right) - 0.16666666666666666 \cdot s}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot s} + \frac{0.25}{\mathsf{PI}\left(\right) \cdot r}}{s}
\end{array}
Initial program 99.5%
Taylor expanded in s around -inf
mul-1-negN/A
distribute-neg-frac2N/A
lower-/.f32N/A
Applied rewrites13.0%
Applied rewrites13.0%
Final simplification13.0%
(FPCore (s r)
:precision binary32
(/
(+
(/ 0.25 (* (PI) r))
(/
(fma (/ 0.06944444444444445 s) (/ r (PI)) (/ -0.16666666666666666 (PI)))
s))
s))\begin{array}{l}
\\
\frac{\frac{0.25}{\mathsf{PI}\left(\right) \cdot r} + \frac{\mathsf{fma}\left(\frac{0.06944444444444445}{s}, \frac{r}{\mathsf{PI}\left(\right)}, \frac{-0.16666666666666666}{\mathsf{PI}\left(\right)}\right)}{s}}{s}
\end{array}
Initial program 99.5%
Taylor expanded in s around -inf
mul-1-negN/A
distribute-neg-frac2N/A
lower-/.f32N/A
Applied rewrites13.0%
Taylor expanded in s around inf
Applied rewrites13.0%
(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 99.5%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites12.9%
(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 99.5%
Taylor expanded in r around 0
lower-/.f32N/A
Applied rewrites11.5%
(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 99.5%
lift-+.f32N/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
lower-fma.f32N/A
Applied rewrites99.6%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
*-commutativeN/A
lift-*.f32N/A
lower-*.f3299.6
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
*-commutativeN/A
associate-/r*N/A
associate-/l*N/A
lower-/.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
lower-PI.f3211.5
Applied rewrites11.5%
(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 99.5%
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.f3211.5
Applied rewrites11.5%
(FPCore (s r) :precision binary32 (/ (/ (+ (/ -0.25 r) (/ 0.16666666666666666 s)) (- (PI))) s))
\begin{array}{l}
\\
\frac{\frac{\frac{-0.25}{r} + \frac{0.16666666666666666}{s}}{-\mathsf{PI}\left(\right)}}{s}
\end{array}
Initial program 99.5%
lift-+.f32N/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
lower-fma.f32N/A
Applied rewrites99.6%
Taylor expanded in s around -inf
mul-1-negN/A
distribute-neg-frac2N/A
lower-/.f32N/A
Applied rewrites11.5%
Final simplification11.5%
(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 99.5%
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.f3210.9
Applied rewrites10.9%
Applied rewrites10.9%
(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 99.5%
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.f3210.9
Applied rewrites10.9%
Applied rewrites10.9%
(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 99.5%
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.f3210.9
Applied rewrites10.9%
Applied rewrites10.9%
Applied rewrites10.9%
(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 99.5%
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.f3210.9
Applied rewrites10.9%
Applied rewrites10.9%
Applied rewrites10.9%
herbie shell --seed 2024352
(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))))