
(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 r) s) (PI))) (/ (* (exp (/ (- r) s)) 0.25) (* (* (* (PI) 2.0) s) r))))
\begin{array}{l}
\\
\frac{e^{\frac{r}{-3 \cdot s}} \cdot 0.75}{\left(\left(6 \cdot r\right) \cdot s\right) \cdot \mathsf{PI}\left(\right)} + \frac{e^{\frac{-r}{s}} \cdot 0.25}{\left(\left(\mathsf{PI}\left(\right) \cdot 2\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
lift-*.f32N/A
*-commutativeN/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f3299.6
lift-*.f32N/A
*-commutativeN/A
lower-*.f3299.6
Applied rewrites99.6%
lift-/.f32N/A
lift-neg.f32N/A
lift-*.f32N/A
metadata-evalN/A
distribute-lft-neg-inN/A
lift-*.f32N/A
frac-2negN/A
lift-/.f3299.6
Applied rewrites99.6%
Final simplification99.6%
(FPCore (s r)
:precision binary32
(let* ((t_0 (exp (/ (- r) s))) (t_1 (* (* (* (PI) 2.0) s) r)))
(if (<=
(+
(/ (* (exp (/ (- r) (* 3.0 s))) 0.75) (* (* (* 6.0 (PI)) s) r))
(/ (* t_0 0.25) t_1))
0.6000000238418579)
(fma
(- 1.0 (/ r s))
(/ 0.25 t_1)
(* (/ 0.125 r) (/ (cbrt t_0) (* (PI) s))))
(/
(-
(/
(-
(/ -0.16666666666666666 (PI))
(/
(*
(-
(/ -0.06944444444444445 (PI))
(* (/ -0.021604938271604937 s) (/ r (PI))))
r)
s))
s)
(/ -0.25 (* (PI) r)))
s))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := e^{\frac{-r}{s}}\\
t_1 := \left(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot s\right) \cdot r\\
\mathbf{if}\;\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{t\_0 \cdot 0.25}{t\_1} \leq 0.6000000238418579:\\
\;\;\;\;\mathsf{fma}\left(1 - \frac{r}{s}, \frac{0.25}{t\_1}, \frac{0.125}{r} \cdot \frac{\sqrt[3]{t\_0}}{\mathsf{PI}\left(\right) \cdot s}\right)\\
\mathbf{else}:\\
\;\;\;\;\frac{\frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{\left(\frac{-0.06944444444444445}{\mathsf{PI}\left(\right)} - \frac{-0.021604938271604937}{s} \cdot \frac{r}{\mathsf{PI}\left(\right)}\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))) < 0.600000024Initial program 99.8%
Taylor expanded in s around inf
mul-1-negN/A
unsub-negN/A
lower--.f32N/A
lower-/.f323.9
Applied rewrites3.9%
Applied rewrites98.3%
if 0.600000024 < (+.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 97.8%
Taylor expanded in s around -inf
Applied rewrites77.6%
Final simplification96.3%
(FPCore (s r)
:precision binary32
(let* ((t_0 (exp (/ (- r) s))))
(if (<=
(+
(/ (* (exp (/ (- r) (* 3.0 s))) 0.75) (* (* (* 6.0 (PI)) s) r))
(/ (* t_0 0.25) (* (* (* (PI) 2.0) s) r)))
0.6000000238418579)
(/
(/
(+ (fma (* (/ r s) r) 0.6666666666666666 r) r)
(/ (/ r (/ t_0 s)) (/ 0.125 (PI))))
r)
(/
(-
(/
(-
(/ -0.16666666666666666 (PI))
(/
(*
(-
(/ -0.06944444444444445 (PI))
(* (/ -0.021604938271604937 s) (/ r (PI))))
r)
s))
s)
(/ -0.25 (* (PI) r)))
s))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := e^{\frac{-r}{s}}\\
\mathbf{if}\;\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{t\_0 \cdot 0.25}{\left(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot s\right) \cdot r} \leq 0.6000000238418579:\\
\;\;\;\;\frac{\frac{\mathsf{fma}\left(\frac{r}{s} \cdot r, 0.6666666666666666, r\right) + r}{\frac{\frac{r}{\frac{t\_0}{s}}}{\frac{0.125}{\mathsf{PI}\left(\right)}}}}{r}\\
\mathbf{else}:\\
\;\;\;\;\frac{\frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{\left(\frac{-0.06944444444444445}{\mathsf{PI}\left(\right)} - \frac{-0.021604938271604937}{s} \cdot \frac{r}{\mathsf{PI}\left(\right)}\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))) < 0.600000024Initial program 99.8%
Applied rewrites3.3%
Taylor expanded in s around inf
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
unpow2N/A
associate-/l*N/A
lower-*.f32N/A
lower-/.f3296.3
Applied rewrites96.3%
if 0.600000024 < (+.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 97.8%
Taylor expanded in s around -inf
Applied rewrites77.6%
Final simplification94.4%
(FPCore (s r) :precision binary32 (+ (/ (* (exp (/ r (* -3.0 s))) 0.75) (* (* (PI) s) (* 6.0 r))) (/ (* (exp (/ (- r) s)) 0.25) (* (* (* (PI) 2.0) 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(\mathsf{PI}\left(\right) \cdot 2\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 (* (* (* (PI) 2.0) s) r)) (exp (/ (- r) s))) (/ (* (exp (/ r (* -3.0 s))) 0.75) (* (* (* 6.0 r) s) (PI)))))
\begin{array}{l}
\\
\frac{0.25}{\left(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot s\right) \cdot r} \cdot e^{\frac{-r}{s}} + \frac{e^{\frac{r}{-3 \cdot s}} \cdot 0.75}{\left(\left(6 \cdot r\right) \cdot s\right) \cdot \mathsf{PI}\left(\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
lift-*.f32N/A
*-commutativeN/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f3299.6
lift-*.f32N/A
*-commutativeN/A
lower-*.f3299.6
Applied rewrites99.6%
lift-/.f32N/A
lift-neg.f32N/A
lift-*.f32N/A
metadata-evalN/A
distribute-lft-neg-inN/A
lift-*.f32N/A
frac-2negN/A
lift-/.f3299.6
Applied rewrites99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-exp.f32N/A
lift-neg.f32N/A
lift-/.f32N/A
*-commutativeN/A
associate-/l*N/A
lower-*.f32N/A
lift-/.f32N/A
lift-neg.f32N/A
lift-exp.f32N/A
lower-/.f3297.3
lift-*.f32N/A
*-commutativeN/A
lower-*.f3297.3
Applied rewrites97.3%
Final simplification97.3%
(FPCore (s r)
:precision binary32
(/
(/
(fma
(* (/ r (PI)) 0.125)
(/ -1.3333333333333333 s)
(/
(/ (fma 0.06944444444444445 (/ (* r r) (PI)) (* (* (/ s (PI)) s) 0.25)) s)
s))
s)
r))\begin{array}{l}
\\
\frac{\frac{\mathsf{fma}\left(\frac{r}{\mathsf{PI}\left(\right)} \cdot 0.125, \frac{-1.3333333333333333}{s}, \frac{\frac{\mathsf{fma}\left(0.06944444444444445, \frac{r \cdot r}{\mathsf{PI}\left(\right)}, \left(\frac{s}{\mathsf{PI}\left(\right)} \cdot s\right) \cdot 0.25\right)}{s}}{s}\right)}{s}}{r}
\end{array}
Initial program 99.6%
Applied rewrites12.6%
Taylor expanded in s around inf
Applied rewrites9.4%
Applied rewrites9.4%
Taylor expanded in s around 0
Applied rewrites40.9%
Final simplification42.5%
(FPCore (s r)
:precision binary32
(/
(/
(/
(/
(fma
0.06944444444444445
(/ (* r r) (PI))
(* (fma (/ r (PI)) -0.16666666666666666 (* (/ s (PI)) 0.25)) s))
s)
s)
s)
r))\begin{array}{l}
\\
\frac{\frac{\frac{\frac{\mathsf{fma}\left(0.06944444444444445, \frac{r \cdot r}{\mathsf{PI}\left(\right)}, \mathsf{fma}\left(\frac{r}{\mathsf{PI}\left(\right)}, -0.16666666666666666, \frac{s}{\mathsf{PI}\left(\right)} \cdot 0.25\right) \cdot s\right)}{s}}{s}}{s}}{r}
\end{array}
Initial program 99.6%
Applied rewrites12.6%
Taylor expanded in s around inf
Applied rewrites9.4%
Applied rewrites9.4%
Taylor expanded in s around 0
Applied rewrites42.9%
(FPCore (s r)
:precision binary32
(/
(-
(/ 0.25 (* (PI) r))
(/
(- (/ (* (/ r (PI)) -0.06944444444444445) s) (/ -0.16666666666666666 (PI)))
s))
s))\begin{array}{l}
\\
\frac{\frac{0.25}{\mathsf{PI}\left(\right) \cdot r} - \frac{\frac{\frac{r}{\mathsf{PI}\left(\right)} \cdot -0.06944444444444445}{s} - \frac{-0.16666666666666666}{\mathsf{PI}\left(\right)}}{s}}{s}
\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%
Taylor expanded in s around -inf
mul-1-negN/A
distribute-neg-fracN/A
Applied rewrites10.8%
Final simplification10.8%
(FPCore (s r) :precision binary32 (/ 1.0 (/ s (- (/ -0.16666666666666666 (* (PI) s)) (/ -0.25 (* (PI) r))))))
\begin{array}{l}
\\
\frac{1}{\frac{s}{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right) \cdot s} - \frac{-0.25}{\mathsf{PI}\left(\right) \cdot r}}}
\end{array}
Initial program 99.6%
Taylor expanded in s around inf
lower-/.f32N/A
Applied rewrites9.5%
Applied rewrites9.5%
(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 rewrites9.5%
(FPCore (s r) :precision binary32 (/ 1.0 (/ s (/ (/ 0.25 (PI)) r))))
\begin{array}{l}
\\
\frac{1}{\frac{s}{\frac{\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.f329.4
Applied rewrites9.4%
Applied rewrites9.4%
Applied rewrites9.4%
Applied rewrites9.5%
(FPCore (s r) :precision binary32 (/ 1.0 (* (* 4.0 (* (PI) s)) r)))
\begin{array}{l}
\\
\frac{1}{\left(4 \cdot \left(\mathsf{PI}\left(\right) \cdot s\right)\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.f329.4
Applied rewrites9.4%
Applied rewrites9.5%
Final simplification9.5%
(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.f329.4
Applied rewrites9.4%
Applied rewrites9.4%
Applied rewrites9.5%
(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.f329.4
Applied rewrites9.4%
Applied rewrites9.4%
herbie shell --seed 2024331
(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))))