
(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 13 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) s)) (* (* (PI) s) r)) 0.125) (/ (* 0.75 (exp (/ (- r) (* 3.0 s)))) (* (* (PI) 6.0) (* s r)))))
\begin{array}{l}
\\
\frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r} \cdot 0.125 + \frac{0.75 \cdot e^{\frac{-r}{3 \cdot s}}}{\left(\mathsf{PI}\left(\right) \cdot 6\right) \cdot \left(s \cdot r\right)}
\end{array}
Initial program 99.7%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-*.f32N/A
lift-PI.f32N/A
lift-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lift-PI.f32N/A
lower-*.f3299.7
Applied rewrites99.7%
Taylor expanded in s around 0
*-commutativeN/A
lower-*.f32N/A
mul-1-negN/A
distribute-frac-negN/A
lower-/.f32N/A
lift-/.f32N/A
lift-neg.f32N/A
lift-exp.f32N/A
*-commutativeN/A
*-commutativeN/A
lift-*.f32N/A
lift-PI.f32N/A
lift-*.f3299.7
Applied rewrites99.7%
(FPCore (s r) :precision binary32 (+ (* (/ (exp (/ (- r) s)) (* (* (PI) s) r)) 0.125) (/ (* 0.75 (exp (/ (- r) (* 3.0 s)))) (* (PI) (* 6.0 (* s r))))))
\begin{array}{l}
\\
\frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r} \cdot 0.125 + \frac{0.75 \cdot e^{\frac{-r}{3 \cdot s}}}{\mathsf{PI}\left(\right) \cdot \left(6 \cdot \left(s \cdot r\right)\right)}
\end{array}
Initial program 99.7%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-*.f32N/A
lift-PI.f32N/A
lift-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lift-PI.f32N/A
lower-*.f3299.7
Applied rewrites99.7%
Taylor expanded in s around 0
*-commutativeN/A
lower-*.f32N/A
mul-1-negN/A
distribute-frac-negN/A
lower-/.f32N/A
lift-/.f32N/A
lift-neg.f32N/A
lift-exp.f32N/A
*-commutativeN/A
*-commutativeN/A
lift-*.f32N/A
lift-PI.f32N/A
lift-*.f3299.7
Applied rewrites99.7%
lift-*.f32N/A
lift-*.f32N/A
lift-PI.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-*.f32N/A
lift-PI.f32N/A
lower-*.f32N/A
lift-*.f3299.7
Applied rewrites99.7%
(FPCore (s r) :precision binary32 (+ (* (/ (exp (/ (- r) s)) (* (* (PI) s) r)) 0.125) (/ (* 0.75 (exp (* -0.3333333333333333 (/ r s)))) (* (* (PI) 6.0) (* s r)))))
\begin{array}{l}
\\
\frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r} \cdot 0.125 + \frac{0.75 \cdot e^{-0.3333333333333333 \cdot \frac{r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot 6\right) \cdot \left(s \cdot r\right)}
\end{array}
Initial program 99.7%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-*.f32N/A
lift-PI.f32N/A
lift-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lift-PI.f32N/A
lower-*.f3299.7
Applied rewrites99.7%
Taylor expanded in s around 0
*-commutativeN/A
lower-*.f32N/A
mul-1-negN/A
distribute-frac-negN/A
lower-/.f32N/A
lift-/.f32N/A
lift-neg.f32N/A
lift-exp.f32N/A
*-commutativeN/A
*-commutativeN/A
lift-*.f32N/A
lift-PI.f32N/A
lift-*.f3299.7
Applied rewrites99.7%
Taylor expanded in s around 0
lower-*.f32N/A
lift-/.f3299.7
Applied rewrites99.7%
(FPCore (s r)
:precision binary32
(+
(* (/ (exp (/ (- r) s)) (* (* (PI) s) r)) 0.125)
(/
(*
0.75
(fma
(/ (fma 0.3333333333333333 r (* -0.05555555555555555 (* (/ r s) r))) s)
-1.0
1.0))
(* (* (PI) 6.0) (* s r)))))\begin{array}{l}
\\
\frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r} \cdot 0.125 + \frac{0.75 \cdot \mathsf{fma}\left(\frac{\mathsf{fma}\left(0.3333333333333333, r, -0.05555555555555555 \cdot \left(\frac{r}{s} \cdot r\right)\right)}{s}, -1, 1\right)}{\left(\mathsf{PI}\left(\right) \cdot 6\right) \cdot \left(s \cdot r\right)}
\end{array}
Initial program 99.7%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-*.f32N/A
lift-PI.f32N/A
lift-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lift-PI.f32N/A
lower-*.f3299.7
Applied rewrites99.7%
Taylor expanded in s around 0
*-commutativeN/A
lower-*.f32N/A
mul-1-negN/A
distribute-frac-negN/A
lower-/.f32N/A
lift-/.f32N/A
lift-neg.f32N/A
lift-exp.f32N/A
*-commutativeN/A
*-commutativeN/A
lift-*.f32N/A
lift-PI.f32N/A
lift-*.f3299.7
Applied rewrites99.7%
Taylor expanded in s around -inf
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lower-/.f32N/A
+-commutativeN/A
lower-fma.f32N/A
lower-*.f32N/A
pow2N/A
associate-*r/N/A
*-commutativeN/A
lower-*.f32N/A
lift-/.f329.3
Applied rewrites9.3%
(FPCore (s r) :precision binary32 (+ (* (/ (exp (/ (- r) s)) (* (* (PI) s) r)) 0.125) (/ (fma (- (* (/ r (* s s)) 0.041666666666666664) (/ 0.25 s)) r 0.75) (* (* (PI) 6.0) (* s r)))))
\begin{array}{l}
\\
\frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r} \cdot 0.125 + \frac{\mathsf{fma}\left(\frac{r}{s \cdot s} \cdot 0.041666666666666664 - \frac{0.25}{s}, r, 0.75\right)}{\left(\mathsf{PI}\left(\right) \cdot 6\right) \cdot \left(s \cdot r\right)}
\end{array}
Initial program 99.7%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-*.f32N/A
lift-PI.f32N/A
lift-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lift-PI.f32N/A
lower-*.f3299.7
Applied rewrites99.7%
Taylor expanded in s around 0
*-commutativeN/A
lower-*.f32N/A
mul-1-negN/A
distribute-frac-negN/A
lower-/.f32N/A
lift-/.f32N/A
lift-neg.f32N/A
lift-exp.f32N/A
*-commutativeN/A
*-commutativeN/A
lift-*.f32N/A
lift-PI.f32N/A
lift-*.f3299.7
Applied rewrites99.7%
Taylor expanded in r around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-/.f32N/A
unpow2N/A
lower-*.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f329.3
Applied rewrites9.3%
(FPCore (s r)
:precision binary32
(/
(-
(fma
(/ r (* (* s s) (PI)))
-0.06944444444444445
(/ 0.16666666666666666 (* (PI) 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{0.16666666666666666}{\mathsf{PI}\left(\right) \cdot s}\right) - \frac{\frac{0.25}{r}}{\mathsf{PI}\left(\right)}}{-s}
\end{array}
Initial program 99.7%
Taylor expanded in s around -inf
Applied rewrites8.6%
Taylor expanded in r around 0
*-commutativeN/A
associate-*r/N/A
metadata-evalN/A
lower-fma.f32N/A
lower-/.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lift-PI.f32N/A
lower-/.f32N/A
*-commutativeN/A
lift-*.f32N/A
lift-PI.f328.8
Applied rewrites8.8%
lift-/.f32N/A
lift-PI.f32N/A
lift-*.f32N/A
*-commutativeN/A
associate-/r*N/A
metadata-evalN/A
associate-*r/N/A
lower-/.f32N/A
associate-*r/N/A
metadata-evalN/A
lift-/.f32N/A
lift-PI.f328.8
Applied rewrites8.8%
Final simplification8.8%
(FPCore (s r)
:precision binary32
(/
(-
(/
(fma (/ s (PI)) 0.16666666666666666 (* -0.06944444444444445 (/ r (PI))))
(* s s))
(/ 0.25 (* (PI) r)))
(- s)))\begin{array}{l}
\\
\frac{\frac{\mathsf{fma}\left(\frac{s}{\mathsf{PI}\left(\right)}, 0.16666666666666666, -0.06944444444444445 \cdot \frac{r}{\mathsf{PI}\left(\right)}\right)}{s \cdot s} - \frac{0.25}{\mathsf{PI}\left(\right) \cdot r}}{-s}
\end{array}
Initial program 99.7%
Taylor expanded in s around -inf
Applied rewrites8.6%
Taylor expanded in r around 0
*-commutativeN/A
associate-*r/N/A
metadata-evalN/A
lower-fma.f32N/A
lower-/.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lift-PI.f32N/A
lower-/.f32N/A
*-commutativeN/A
lift-*.f32N/A
lift-PI.f328.8
Applied rewrites8.8%
Taylor expanded in s around 0
lower-/.f32N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lower-/.f32N/A
lift-PI.f32N/A
lower-*.f32N/A
lower-/.f32N/A
lift-PI.f32N/A
pow2N/A
lift-*.f328.8
Applied rewrites8.8%
Final simplification8.8%
(FPCore (s r)
:precision binary32
(let* ((t_0 (* (PI) s)))
(/
(-
(fma (/ r (* s t_0)) -0.06944444444444445 (/ 0.16666666666666666 t_0))
(/ 0.25 (* (PI) r)))
(- s))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \mathsf{PI}\left(\right) \cdot s\\
\frac{\mathsf{fma}\left(\frac{r}{s \cdot t\_0}, -0.06944444444444445, \frac{0.16666666666666666}{t\_0}\right) - \frac{0.25}{\mathsf{PI}\left(\right) \cdot r}}{-s}
\end{array}
\end{array}
Initial program 99.7%
Taylor expanded in s around -inf
Applied rewrites8.6%
Taylor expanded in r around 0
*-commutativeN/A
associate-*r/N/A
metadata-evalN/A
lower-fma.f32N/A
lower-/.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lift-PI.f32N/A
lower-/.f32N/A
*-commutativeN/A
lift-*.f32N/A
lift-PI.f328.8
Applied rewrites8.8%
lift-*.f32N/A
lift-PI.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
lift-PI.f328.8
Applied rewrites8.8%
Final simplification8.8%
(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%
Taylor expanded in s around -inf
Applied rewrites8.6%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites8.8%
(FPCore (s r) :precision binary32 (/ (/ (- (* (/ (/ r s) (PI)) 0.16666666666666666) (/ 0.25 (PI))) r) (- s)))
\begin{array}{l}
\\
\frac{\frac{\frac{\frac{r}{s}}{\mathsf{PI}\left(\right)} \cdot 0.16666666666666666 - \frac{0.25}{\mathsf{PI}\left(\right)}}{r}}{-s}
\end{array}
Initial program 99.7%
Taylor expanded in s around -inf
Applied rewrites8.6%
Taylor expanded in r around 0
lower-/.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
associate-/r*N/A
lower-/.f32N/A
lift-/.f32N/A
lift-PI.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
lift-PI.f328.2
Applied rewrites8.2%
Final simplification8.2%
(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 99.7%
Taylor expanded in s around inf
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lift-PI.f328.2
Applied rewrites8.2%
lift-/.f32N/A
lift-*.f32N/A
lift-PI.f32N/A
lift-*.f32N/A
associate-/r*N/A
metadata-evalN/A
*-commutativeN/A
associate-*r/N/A
lower-/.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
*-commutativeN/A
lift-*.f32N/A
lift-PI.f328.2
Applied rewrites8.2%
(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%
Taylor expanded in s around inf
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lift-PI.f328.2
Applied rewrites8.2%
(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 99.7%
Taylor expanded in s around inf
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lift-PI.f328.2
Applied rewrites8.2%
lift-*.f32N/A
lift-PI.f32N/A
lift-*.f32N/A
*-commutativeN/A
*-commutativeN/A
associate-*r*N/A
*-commutativeN/A
lower-*.f32N/A
lift-*.f32N/A
lift-PI.f328.2
Applied rewrites8.2%
herbie shell --seed 2025040
(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))))