
(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 11 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 99.7%
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 (+ (/ (* (exp (* (/ r s) -0.3333333333333333)) 0.75) (* (* (* 6.0 (PI)) r) s)) (/ (* (exp (/ (- r) s)) 0.25) (* (* s r) (* 2.0 (PI))))))
\begin{array}{l}
\\
\frac{e^{\frac{r}{s} \cdot -0.3333333333333333} \cdot 0.75}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot r\right) \cdot s} + \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 99.7%
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%
lift-/.f32N/A
lift-neg.f32N/A
lift-*.f32N/A
neg-mul-1N/A
times-fracN/A
lift-/.f32N/A
lower-*.f32N/A
metadata-eval99.7
Applied rewrites99.7%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
*-commutativeN/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f3299.7
Applied rewrites99.7%
Final simplification99.7%
(FPCore (s r)
:precision binary32
(*
(+
(/
(-
(*
(/ (- -0.06944444444444445 (* (/ -0.021604938271604937 s) r)) (PI))
(/ r s))
(/ -0.16666666666666666 (PI)))
s)
(/ -0.25 (* (PI) r)))
(/ -1.0 s)))\begin{array}{l}
\\
\left(\frac{\frac{-0.06944444444444445 - \frac{-0.021604938271604937}{s} \cdot r}{\mathsf{PI}\left(\right)} \cdot \frac{r}{s} - \frac{-0.16666666666666666}{\mathsf{PI}\left(\right)}}{s} + \frac{-0.25}{\mathsf{PI}\left(\right) \cdot r}\right) \cdot \frac{-1}{s}
\end{array}
Initial program 99.7%
Taylor expanded in s around -inf
Applied rewrites12.2%
Applied rewrites12.2%
Final simplification12.2%
(FPCore (s r)
:precision binary32
(let* ((t_0 (* (PI) r)))
(/
(-
(*
t_0
(-
(/ -0.16666666666666666 (PI))
(*
(/ (- -0.06944444444444445 (* (/ -0.021604938271604937 s) r)) (PI))
(/ r s))))
(* -0.25 s))
(* (* t_0 s) s))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \mathsf{PI}\left(\right) \cdot r\\
\frac{t\_0 \cdot \left(\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{-0.06944444444444445 - \frac{-0.021604938271604937}{s} \cdot r}{\mathsf{PI}\left(\right)} \cdot \frac{r}{s}\right) - -0.25 \cdot s}{\left(t\_0 \cdot s\right) \cdot s}
\end{array}
\end{array}
Initial program 99.7%
Taylor expanded in s around -inf
Applied rewrites12.2%
Applied rewrites12.2%
Final simplification12.2%
(FPCore (s r)
:precision binary32
(/
(-
(/
(-
(/ -0.16666666666666666 (PI))
(/
(* (/ (- -0.06944444444444445 (* (/ -0.021604938271604937 s) r)) (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 - \frac{-0.021604938271604937}{s} \cdot r}{\mathsf{PI}\left(\right)} \cdot r}{s}}{s} - \frac{-0.25}{\mathsf{PI}\left(\right) \cdot r}}{s}
\end{array}
Initial program 99.7%
Taylor expanded in s around -inf
Applied rewrites12.2%
Applied rewrites12.2%
(FPCore (s r)
:precision binary32
(/
(-
(/
(- (/ -0.16666666666666666 (PI)) (/ (* (/ r (PI)) -0.06944444444444445) s))
s)
(/ -0.25 (* (PI) r)))
s))\begin{array}{l}
\\
\frac{\frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{\frac{r}{\mathsf{PI}\left(\right)} \cdot -0.06944444444444445}{s}}{s} - \frac{-0.25}{\mathsf{PI}\left(\right) \cdot r}}{s}
\end{array}
Initial program 99.7%
Taylor expanded in s around -inf
Applied rewrites12.2%
Taylor expanded in s around inf
Applied rewrites12.2%
(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 99.7%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites11.4%
(FPCore (s r) :precision binary32 (/ (* (/ 1.0 r) (/ 0.25 (PI))) s))
\begin{array}{l}
\\
\frac{\frac{1}{r} \cdot \frac{0.25}{\mathsf{PI}\left(\right)}}{s}
\end{array}
Initial program 99.7%
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.f3210.2
Applied rewrites10.2%
Applied rewrites10.2%
Final simplification10.2%
(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 99.7%
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.f3210.2
Applied rewrites10.2%
Applied rewrites10.2%
Applied rewrites10.2%
(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 99.7%
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.f3210.2
Applied rewrites10.2%
Applied rewrites10.2%
(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
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.f3210.2
Applied rewrites10.2%
Applied rewrites10.2%
Applied rewrites10.2%
herbie shell --seed 2024248
(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))))