
(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 16 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 (+ (/ (* 0.25 (exp (/ (- r) s))) (* (* (* 2.0 (PI)) s) r)) (/ (* 0.75 (exp (* -0.3333333333333333 (/ r 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^{-0.3333333333333333 \cdot \frac{r}{s}}}{6 \cdot \left(\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r\right)}
\end{array}
Initial program 99.7%
lift-*.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-*l*N/A
lower-*.f32N/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%
(FPCore (s r)
:precision binary32
(if (<=
(+
(/ (* 0.25 (exp (/ (- r) s))) (* (* (* 2.0 (PI)) s) r))
(/ (* 0.75 (exp (/ (- r) (* 3.0 s)))) (* (* (* 6.0 (PI)) s) r)))
4.999999873689376e-6)
(fma
(/ (fma (/ -1.0 s) r 1.0) (* (* (* (PI) 2.0) s) r))
0.25
(* (/ (pow (exp r) (/ -0.3333333333333333 s)) (* (PI) s)) (/ 0.125 r)))
(/
(-
(*
(/
(-
(/ -0.16666666666666666 (PI))
(*
(/ (- -0.06944444444444445 (* (/ -0.021604938271604937 s) r)) (PI))
(/ r s)))
s)
s)
(* s (/ -0.25 (* (PI) r))))
(* s s))))\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\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} \leq 4.999999873689376 \cdot 10^{-6}:\\
\;\;\;\;\mathsf{fma}\left(\frac{\mathsf{fma}\left(\frac{-1}{s}, r, 1\right)}{\left(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot s\right) \cdot r}, 0.25, \frac{{\left(e^{r}\right)}^{\left(\frac{-0.3333333333333333}{s}\right)}}{\mathsf{PI}\left(\right) \cdot s} \cdot \frac{0.125}{r}\right)\\
\mathbf{else}:\\
\;\;\;\;\frac{\frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{-0.06944444444444445 - \frac{-0.021604938271604937}{s} \cdot r}{\mathsf{PI}\left(\right)} \cdot \frac{r}{s}}{s} \cdot s - s \cdot \frac{-0.25}{\mathsf{PI}\left(\right) \cdot r}}{s \cdot 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))) < 4.99999987e-6Initial program 99.8%
Taylor expanded in s around inf
Applied rewrites5.0%
lift-/.f32N/A
lift-neg.f32N/A
lift-*.f32N/A
neg-mul-1N/A
times-fracN/A
lift-/.f32N/A
lower-*.f32N/A
metadata-eval5.1
Applied rewrites5.1%
Taylor expanded in s around inf
Applied rewrites4.9%
Applied rewrites98.0%
if 4.99999987e-6 < (+.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 98.3%
Taylor expanded in s around -inf
Applied rewrites77.1%
Applied rewrites77.2%
(FPCore (s r)
:precision binary32
(if (<=
(+
(/ (* 0.25 (exp (/ (- r) s))) (* (* (* 2.0 (PI)) s) r))
(/ (* 0.75 (exp (/ (- r) (* 3.0 s)))) (* (* (* 6.0 (PI)) s) r)))
4.999999873689376e-6)
(fma
0.25
(/ (fma (/ -1.0 s) r 1.0) (* (* (* (PI) 2.0) s) r))
(* (/ (pow (exp r) (/ -0.3333333333333333 s)) (* (PI) s)) (/ 0.125 r)))
(/
(-
(*
(/
(-
(/ -0.16666666666666666 (PI))
(*
(/ (- -0.06944444444444445 (* (/ -0.021604938271604937 s) r)) (PI))
(/ r s)))
s)
s)
(* s (/ -0.25 (* (PI) r))))
(* s s))))\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\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} \leq 4.999999873689376 \cdot 10^{-6}:\\
\;\;\;\;\mathsf{fma}\left(0.25, \frac{\mathsf{fma}\left(\frac{-1}{s}, r, 1\right)}{\left(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot s\right) \cdot r}, \frac{{\left(e^{r}\right)}^{\left(\frac{-0.3333333333333333}{s}\right)}}{\mathsf{PI}\left(\right) \cdot s} \cdot \frac{0.125}{r}\right)\\
\mathbf{else}:\\
\;\;\;\;\frac{\frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{-0.06944444444444445 - \frac{-0.021604938271604937}{s} \cdot r}{\mathsf{PI}\left(\right)} \cdot \frac{r}{s}}{s} \cdot s - s \cdot \frac{-0.25}{\mathsf{PI}\left(\right) \cdot r}}{s \cdot 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))) < 4.99999987e-6Initial program 99.8%
Taylor expanded in s around inf
Applied rewrites5.0%
lift-/.f32N/A
lift-neg.f32N/A
lift-*.f32N/A
neg-mul-1N/A
times-fracN/A
lift-/.f32N/A
lower-*.f32N/A
metadata-eval5.1
Applied rewrites5.1%
Taylor expanded in s around inf
Applied rewrites4.9%
Applied rewrites97.6%
if 4.99999987e-6 < (+.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 98.3%
Taylor expanded in s around -inf
Applied rewrites77.1%
Applied rewrites77.2%
(FPCore (s r) :precision binary32 (+ (* (exp (/ (- r) s)) (/ 0.25 (* (* (* (PI) 2.0) s) r))) (/ (* 0.75 (exp (* -0.3333333333333333 (/ r s)))) (* 6.0 (* (* (PI) s) r)))))
\begin{array}{l}
\\
e^{\frac{-r}{s}} \cdot \frac{0.25}{\left(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot s\right) \cdot r} + \frac{0.75 \cdot e^{-0.3333333333333333 \cdot \frac{r}{s}}}{6 \cdot \left(\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r\right)}
\end{array}
Initial program 99.7%
lift-*.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-*l*N/A
lower-*.f32N/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
lift-exp.f32N/A
lift-/.f32N/A
lift-neg.f32N/A
*-commutativeN/A
associate-/l*N/A
lower-*.f32N/A
lift-neg.f32N/A
lift-/.f32N/A
lift-exp.f32N/A
lower-/.f3298.1
lift-*.f32N/A
*-commutativeN/A
lower-*.f3298.1
Applied rewrites98.1%
(FPCore (s r)
:precision binary32
(/
(-
(*
(/
(-
(/ -0.16666666666666666 (PI))
(*
(/ (- -0.06944444444444445 (* (/ -0.021604938271604937 s) r)) (PI))
(/ r s)))
s)
s)
(* s (/ -0.25 (* (PI) r))))
(* s s)))\begin{array}{l}
\\
\frac{\frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{-0.06944444444444445 - \frac{-0.021604938271604937}{s} \cdot r}{\mathsf{PI}\left(\right)} \cdot \frac{r}{s}}{s} \cdot s - s \cdot \frac{-0.25}{\mathsf{PI}\left(\right) \cdot r}}{s \cdot s}
\end{array}
Initial program 99.7%
Taylor expanded in s around -inf
Applied rewrites11.2%
Applied rewrites11.2%
(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))
(* s (* t_0 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}{s \cdot \left(t\_0 \cdot s\right)}
\end{array}
\end{array}
Initial program 99.7%
Taylor expanded in s around -inf
Applied rewrites11.2%
Applied rewrites11.2%
(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 rewrites11.2%
Applied rewrites11.2%
(FPCore (s r)
:precision binary32
(+
(/
(-
(/ -0.16666666666666666 (PI))
(*
(/ (fma (/ 0.021604938271604937 s) r -0.06944444444444445) s)
(/ r (PI))))
(* s s))
(/ 0.25 (* (* s r) (PI)))))\begin{array}{l}
\\
\frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{\mathsf{fma}\left(\frac{0.021604938271604937}{s}, r, -0.06944444444444445\right)}{s} \cdot \frac{r}{\mathsf{PI}\left(\right)}}{s \cdot s} + \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
Applied rewrites11.2%
Applied rewrites11.2%
Applied rewrites10.1%
Applied rewrites11.0%
(FPCore (s r)
:precision binary32
(/
(-
(/
(- (/ -0.16666666666666666 (PI)) (/ (* r (/ -0.06944444444444445 (PI))) s))
s)
(/ -0.25 (* (PI) r)))
s))\begin{array}{l}
\\
\frac{\frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{r \cdot \frac{-0.06944444444444445}{\mathsf{PI}\left(\right)}}{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 rewrites11.2%
Taylor expanded in s around inf
Applied rewrites11.1%
(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 99.7%
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-*.f3299.7
Applied rewrites99.7%
Taylor expanded in s around inf
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
Applied rewrites10.1%
Final simplification10.1%
(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 rewrites10.1%
(FPCore (s r) :precision binary32 (let* ((t_0 (sqrt (PI)))) (/ 0.25 (* (* (* r t_0) t_0) s))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{\mathsf{PI}\left(\right)}\\
\frac{0.25}{\left(\left(r \cdot t\_0\right) \cdot t\_0\right) \cdot s}
\end{array}
\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.f3210.0
Applied rewrites10.0%
Applied rewrites10.0%
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
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.f3210.0
Applied rewrites10.0%
Applied rewrites10.0%
(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 99.7%
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.f3210.0
Applied rewrites10.0%
Applied rewrites10.0%
(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.f3210.0
Applied rewrites10.0%
Applied rewrites10.0%
(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.f3210.0
Applied rewrites10.0%
Applied rewrites10.0%
Applied rewrites10.0%
herbie shell --seed 2024308
(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))))