
(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 12 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 (+ (/ (* (pow (E) (* (/ r s) -0.3333333333333333)) 0.75) (* (* (* 6.0 (PI)) s) r)) (/ (* (exp (/ (- r) s)) 0.25) (* (* (* (PI) 2.0) s) r))))
\begin{array}{l}
\\
\frac{{\mathsf{E}\left(\right)}^{\left(\frac{r}{s} \cdot -0.3333333333333333\right)} \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(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot s\right) \cdot r}
\end{array}
Initial program 99.4%
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-eval99.4
Applied rewrites99.4%
lift-exp.f32N/A
lift-/.f32N/A
frac-2negN/A
lift-*.f32N/A
distribute-lft-neg-inN/A
metadata-evalN/A
lift-neg.f32N/A
lift-*.f32N/A
clear-numN/A
div-invN/A
clear-numN/A
lift-/.f32N/A
exp-prodN/A
lower-pow.f32N/A
exp-1-eN/A
lower-E.f3299.4
lift-/.f32N/A
lift-neg.f32N/A
lift-*.f32N/A
neg-mul-1N/A
times-fracN/A
lower-*.f32N/A
metadata-evalN/A
lower-/.f3299.5
Applied rewrites99.5%
Final simplification99.5%
(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)))
9.999999682655225e-22)
(fma
(/ (/ 0.125 s) (PI))
(/ (fma (/ r s) -0.3333333333333333 1.0) r)
(* (/ t_0 (- r)) (/ (/ -0.125 s) (PI))))
(/
(+
(/ 0.25 (* (PI) r))
(/
(-
(/ -0.16666666666666666 (PI))
(/
(fma
(/ -0.041666666666666664 r)
(/ (* 0.16666666666666666 (* r r)) (PI))
(* -0.0625 (/ r (PI))))
s))
s))
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 9.999999682655225 \cdot 10^{-22}:\\
\;\;\;\;\mathsf{fma}\left(\frac{\frac{0.125}{s}}{\mathsf{PI}\left(\right)}, \frac{\mathsf{fma}\left(\frac{r}{s}, -0.3333333333333333, 1\right)}{r}, \frac{t\_0}{-r} \cdot \frac{\frac{-0.125}{s}}{\mathsf{PI}\left(\right)}\right)\\
\mathbf{else}:\\
\;\;\;\;\frac{\frac{0.25}{\mathsf{PI}\left(\right) \cdot r} + \frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{\mathsf{fma}\left(\frac{-0.041666666666666664}{r}, \frac{0.16666666666666666 \cdot \left(r \cdot r\right)}{\mathsf{PI}\left(\right)}, -0.0625 \cdot \frac{r}{\mathsf{PI}\left(\right)}\right)}{s}}{s}}{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))) < 9.9999997e-22Initial program 99.7%
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-eval99.7
Applied rewrites99.7%
Taylor expanded in s around inf
+-commutativeN/A
lower-fma.f32N/A
lower-/.f324.7
Applied rewrites4.7%
Applied rewrites99.2%
lift-/.f32N/A
frac-2negN/A
lower-/.f32N/A
lift-/.f32N/A
distribute-neg-fracN/A
lower-/.f32N/A
metadata-evalN/A
lower-neg.f3299.2
Applied rewrites99.2%
if 9.9999997e-22 < (+.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 96.5%
Taylor expanded in s around inf
Applied rewrites41.1%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
times-fracN/A
lower-fma.f32N/A
Applied rewrites24.9%
Taylor expanded in s around -inf
Applied rewrites50.3%
Final simplification87.5%
(FPCore (s r)
:precision binary32
(let* ((t_0 (exp (/ (- r) s))) (t_1 (/ (/ 0.125 s) (PI))))
(if (<=
(+
(/ (* (exp (/ (- r) (* 3.0 s))) 0.75) (* (* (* 6.0 (PI)) s) r))
(/ (* t_0 0.25) (* (* (* (PI) 2.0) s) r)))
1.999999967550318e-17)
(fma t_1 (/ 1.0 r) (* (/ t_0 r) t_1))
(/
(+
(/ 0.25 (* (PI) r))
(/
(-
(/ -0.16666666666666666 (PI))
(/
(fma
(/ -0.041666666666666664 r)
(/ (* 0.16666666666666666 (* r r)) (PI))
(* -0.0625 (/ r (PI))))
s))
s))
s))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := e^{\frac{-r}{s}}\\
t_1 := \frac{\frac{0.125}{s}}{\mathsf{PI}\left(\right)}\\
\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 1.999999967550318 \cdot 10^{-17}:\\
\;\;\;\;\mathsf{fma}\left(t\_1, \frac{1}{r}, \frac{t\_0}{r} \cdot t\_1\right)\\
\mathbf{else}:\\
\;\;\;\;\frac{\frac{0.25}{\mathsf{PI}\left(\right) \cdot r} + \frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{\mathsf{fma}\left(\frac{-0.041666666666666664}{r}, \frac{0.16666666666666666 \cdot \left(r \cdot r\right)}{\mathsf{PI}\left(\right)}, -0.0625 \cdot \frac{r}{\mathsf{PI}\left(\right)}\right)}{s}}{s}}{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))) < 1.99999997e-17Initial program 99.7%
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-eval99.7
Applied rewrites99.7%
Taylor expanded in s around inf
+-commutativeN/A
lower-fma.f32N/A
lower-/.f324.7
Applied rewrites4.7%
Applied rewrites98.8%
Taylor expanded in s around inf
Applied rewrites98.8%
if 1.99999997e-17 < (+.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 96.9%
Taylor expanded in s around inf
Applied rewrites42.3%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
times-fracN/A
lower-fma.f32N/A
Applied rewrites25.5%
Taylor expanded in s around -inf
Applied rewrites55.4%
Final simplification91.3%
(FPCore (s r) :precision binary32 (+ (/ (* (pow (E) (* (/ r s) -0.3333333333333333)) 0.75) (* (* (* 6.0 s) r) (PI))) (/ (* (exp (/ (- r) s)) 0.25) (* (* (* (PI) 2.0) s) r))))
\begin{array}{l}
\\
\frac{{\mathsf{E}\left(\right)}^{\left(\frac{r}{s} \cdot -0.3333333333333333\right)} \cdot 0.75}{\left(\left(6 \cdot s\right) \cdot r\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 99.4%
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-eval99.4
Applied rewrites99.4%
lift-exp.f32N/A
lift-/.f32N/A
frac-2negN/A
lift-*.f32N/A
distribute-lft-neg-inN/A
metadata-evalN/A
lift-neg.f32N/A
lift-*.f32N/A
clear-numN/A
div-invN/A
clear-numN/A
lift-/.f32N/A
exp-prodN/A
lower-pow.f32N/A
exp-1-eN/A
lower-E.f3299.4
lift-/.f32N/A
lift-neg.f32N/A
lift-*.f32N/A
neg-mul-1N/A
times-fracN/A
lower-*.f32N/A
metadata-evalN/A
lower-/.f3299.5
Applied rewrites99.5%
lift-*.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
*-commutativeN/A
associate-*l*N/A
lower-*.f32N/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f3299.4
Applied rewrites99.4%
Final simplification99.4%
(FPCore (s r) :precision binary32 (+ (/ (* (exp (* (/ -0.3333333333333333 s) r)) 0.75) (* (* s r) (* 6.0 (PI)))) (/ (* (exp (/ (- r) s)) 0.25) (* (* (* (PI) 2.0) s) r))))
\begin{array}{l}
\\
\frac{e^{\frac{-0.3333333333333333}{s} \cdot r} \cdot 0.75}{\left(s \cdot r\right) \cdot \left(6 \cdot \mathsf{PI}\left(\right)\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 99.4%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
*-commutativeN/A
lower-*.f32N/A
lower-*.f3299.4
Applied rewrites99.4%
lift-/.f32N/A
lift-*.f32N/A
lift-neg.f32N/A
metadata-evalN/A
distribute-lft-neg-inN/A
lift-*.f32N/A
frac-2negN/A
div-invN/A
*-commutativeN/A
lower-*.f32N/A
lift-*.f32N/A
associate-/r*N/A
metadata-evalN/A
metadata-evalN/A
lower-/.f32N/A
metadata-eval99.4
Applied rewrites99.4%
Final simplification99.4%
(FPCore (s r) :precision binary32 (+ (/ (* (exp (* (/ r s) -0.3333333333333333)) 0.75) (* (* (* 6.0 (PI)) s) r)) (/ (* (exp (/ (- r) s)) 0.25) (* (* (* (PI) 2.0) s) r))))
\begin{array}{l}
\\
\frac{e^{\frac{r}{s} \cdot -0.3333333333333333} \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(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot s\right) \cdot r}
\end{array}
Initial program 99.4%
lift-/.f32N/A
lift-neg.f32N/A
neg-mul-1N/A
lift-*.f32N/A
times-fracN/A
lower-*.f32N/A
metadata-evalN/A
lower-/.f3299.4
Applied rewrites99.4%
Final simplification99.4%
(FPCore (s r) :precision binary32 (fma 1.0 (/ 0.25 (* (* (* (PI) 2.0) s) r)) (* (/ (/ 0.125 s) (PI)) (/ (cbrt (exp (/ (- r) s))) r))))
\begin{array}{l}
\\
\mathsf{fma}\left(1, \frac{0.25}{\left(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot s\right) \cdot r}, \frac{\frac{0.125}{s}}{\mathsf{PI}\left(\right)} \cdot \frac{\sqrt[3]{e^{\frac{-r}{s}}}}{r}\right)
\end{array}
Initial program 99.4%
Taylor expanded in s around inf
Applied rewrites8.7%
lift-+.f32N/A
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
associate-/l*N/A
lower-fma.f32N/A
Applied rewrites92.9%
Final simplification92.9%
(FPCore (s r)
:precision binary32
(/
(+
(/ 0.25 (* (PI) r))
(/
(-
(/ -0.16666666666666666 (PI))
(/
(fma
(/ -0.041666666666666664 r)
(/ (* 0.16666666666666666 (* r r)) (PI))
(* -0.0625 (/ r (PI))))
s))
s))
s))\begin{array}{l}
\\
\frac{\frac{0.25}{\mathsf{PI}\left(\right) \cdot r} + \frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{\mathsf{fma}\left(\frac{-0.041666666666666664}{r}, \frac{0.16666666666666666 \cdot \left(r \cdot r\right)}{\mathsf{PI}\left(\right)}, -0.0625 \cdot \frac{r}{\mathsf{PI}\left(\right)}\right)}{s}}{s}}{s}
\end{array}
Initial program 99.4%
Taylor expanded in s around inf
Applied rewrites8.7%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
times-fracN/A
lower-fma.f32N/A
Applied rewrites6.9%
Taylor expanded in s around -inf
Applied rewrites9.0%
Final simplification9.0%
(FPCore (s r)
:precision binary32
(/
(+
(/
(- (/ -0.16666666666666666 (PI)) (/ (* -0.06944444444444445 (/ r (PI))) s))
s)
(/ 0.25 (* (PI) r)))
s))\begin{array}{l}
\\
\frac{\frac{\frac{-0.16666666666666666}{\mathsf{PI}\left(\right)} - \frac{-0.06944444444444445 \cdot \frac{r}{\mathsf{PI}\left(\right)}}{s}}{s} + \frac{0.25}{\mathsf{PI}\left(\right) \cdot r}}{s}
\end{array}
Initial program 99.4%
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-eval99.4
Applied rewrites99.4%
lift-exp.f32N/A
lift-/.f32N/A
lift-*.f32N/A
metadata-evalN/A
distribute-lft-neg-inN/A
lift-*.f32N/A
distribute-frac-neg2N/A
neg-mul-1N/A
exp-prodN/A
lower-pow.f32N/A
lower-exp.f32N/A
div-invN/A
lower-*.f32N/A
lift-*.f32N/A
associate-/r*N/A
metadata-evalN/A
lower-/.f3299.4
Applied rewrites99.4%
Taylor expanded in s around -inf
associate-*r/N/A
mul-1-negN/A
Applied rewrites9.0%
(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 99.4%
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.f328.6
Applied rewrites8.6%
Applied rewrites8.6%
(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 99.4%
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.f328.6
Applied rewrites8.6%
Applied rewrites8.6%
Applied rewrites8.6%
(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 99.4%
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.f328.6
Applied rewrites8.6%
Applied rewrites8.6%
Applied rewrites8.6%
herbie shell --seed 2024278
(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))))