
(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
(let* ((t_0 (cbrt (PI))))
(+
(/ (/ 0.125 (exp (/ r s))) (* (* (PI) s) r))
(/
(* 0.75 (exp (* r (/ -0.3333333333333333 s))))
(* (pow t_0 2.0) (* t_0 (* (* s r) 6.0)))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt[3]{\mathsf{PI}\left(\right)}\\
\frac{\frac{0.125}{e^{\frac{r}{s}}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r} + \frac{0.75 \cdot e^{r \cdot \frac{-0.3333333333333333}{s}}}{{t\_0}^{2} \cdot \left(t\_0 \cdot \left(\left(s \cdot r\right) \cdot 6\right)\right)}
\end{array}
\end{array}
Initial program 99.6%
lift-/.f32N/A
frac-2negN/A
div-invN/A
lift-neg.f32N/A
remove-double-negN/A
lower-*.f32N/A
lift-*.f32N/A
distribute-lft-neg-inN/A
associate-/r*N/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower-/.f32N/A
metadata-eval99.6
Applied rewrites99.6%
Taylor expanded in s around 0
associate-*r/N/A
lower-/.f32N/A
mul-1-negN/A
exp-negN/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
lower-exp.f32N/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3299.6
Applied rewrites99.6%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-*.f32N/A
lift-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-*.f3299.6
Applied rewrites99.6%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lift-PI.f32N/A
add-cube-cbrtN/A
associate-*l*N/A
lower-*.f32N/A
pow2N/A
lower-pow.f32N/A
lift-PI.f32N/A
lower-cbrt.f32N/A
lower-*.f32N/A
lift-PI.f32N/A
lower-cbrt.f32N/A
*-commutativeN/A
lower-*.f3299.7
Applied rewrites99.7%
(FPCore (s r)
:precision binary32
(let* ((t_0 (exp (/ (- r) s)))
(t_1 (/ (* 0.25 t_0) (* (* (* 2.0 (PI)) s) r)))
(t_2 (/ r (PI))))
(if (<=
(+ t_1 (/ (* 0.75 (exp (/ (- r) (* 3.0 s)))) (* (* (* 6.0 (PI)) s) r)))
4.999999969612645e-9)
(fma
(cbrt t_0)
(* 0.75 (/ 0.16666666666666666 (* (* (PI) s) r)))
(/ (fma (/ r s) -0.25 0.25) (* (* (* (PI) 2.0) s) r)))
(+
t_1
(/
(-
(/
(-
(/ -0.041666666666666664 (PI))
(/
(fma
0.0007716049382716049
(* (/ t_2 s) r)
(* -0.006944444444444444 t_2))
s))
s)
(/ -0.125 (* (PI) r)))
s)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := e^{\frac{-r}{s}}\\
t_1 := \frac{0.25 \cdot t\_0}{\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}\\
t_2 := \frac{r}{\mathsf{PI}\left(\right)}\\
\mathbf{if}\;t\_1 + \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 4.999999969612645 \cdot 10^{-9}:\\
\;\;\;\;\mathsf{fma}\left(\sqrt[3]{t\_0}, 0.75 \cdot \frac{0.16666666666666666}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r}, \frac{\mathsf{fma}\left(\frac{r}{s}, -0.25, 0.25\right)}{\left(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot s\right) \cdot r}\right)\\
\mathbf{else}:\\
\;\;\;\;t\_1 + \frac{\frac{\frac{-0.041666666666666664}{\mathsf{PI}\left(\right)} - \frac{\mathsf{fma}\left(0.0007716049382716049, \frac{t\_2}{s} \cdot r, -0.006944444444444444 \cdot t\_2\right)}{s}}{s} - \frac{-0.125}{\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))) < 4.99999997e-9Initial program 99.8%
Taylor expanded in s around inf
+-commutativeN/A
lower-fma.f32N/A
lower-/.f324.7
Applied rewrites4.7%
Applied rewrites8.9%
if 4.99999997e-9 < (+.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 rewrites34.0%
(FPCore (s r) :precision binary32 (+ (/ (/ 0.125 (exp (/ r s))) (* (* (PI) s) r)) (/ (* 0.75 (exp (* r (/ -0.3333333333333333 s)))) (* (* (PI) 6.0) (* s r)))))
\begin{array}{l}
\\
\frac{\frac{0.125}{e^{\frac{r}{s}}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r} + \frac{0.75 \cdot e^{r \cdot \frac{-0.3333333333333333}{s}}}{\left(\mathsf{PI}\left(\right) \cdot 6\right) \cdot \left(s \cdot r\right)}
\end{array}
Initial program 99.6%
lift-/.f32N/A
frac-2negN/A
div-invN/A
lift-neg.f32N/A
remove-double-negN/A
lower-*.f32N/A
lift-*.f32N/A
distribute-lft-neg-inN/A
associate-/r*N/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower-/.f32N/A
metadata-eval99.6
Applied rewrites99.6%
Taylor expanded in s around 0
associate-*r/N/A
lower-/.f32N/A
mul-1-negN/A
exp-negN/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
lower-exp.f32N/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3299.6
Applied rewrites99.6%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-*.f32N/A
lift-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-*.f3299.6
Applied rewrites99.6%
(FPCore (s r) :precision binary32 (+ (/ (/ 0.125 (exp (/ r s))) (* (* r (PI)) s)) (/ (* 0.75 (exp (* r (/ -0.3333333333333333 s)))) (* (* (* 6.0 (PI)) s) r))))
\begin{array}{l}
\\
\frac{\frac{0.125}{e^{\frac{r}{s}}}}{\left(r \cdot \mathsf{PI}\left(\right)\right) \cdot s} + \frac{0.75 \cdot e^{r \cdot \frac{-0.3333333333333333}{s}}}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}
\end{array}
Initial program 99.6%
lift-/.f32N/A
frac-2negN/A
div-invN/A
lift-neg.f32N/A
remove-double-negN/A
lower-*.f32N/A
lift-*.f32N/A
distribute-lft-neg-inN/A
associate-/r*N/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower-/.f32N/A
metadata-eval99.6
Applied rewrites99.6%
Taylor expanded in s around 0
associate-*r/N/A
lower-/.f32N/A
mul-1-negN/A
exp-negN/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
lower-exp.f32N/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3299.6
Applied rewrites99.6%
Applied rewrites99.6%
(FPCore (s r) :precision binary32 (+ (* (exp (/ (- r) s)) (/ 0.125 (* (* (PI) s) r))) (/ (* 0.75 (exp (/ (- r) (* 3.0 s)))) (* (* (* 6.0 (PI)) s) r))))
\begin{array}{l}
\\
e^{\frac{-r}{s}} \cdot \frac{0.125}{\left(\mathsf{PI}\left(\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}
Initial program 99.6%
lift-/.f32N/A
lift-*.f32N/A
*-commutativeN/A
associate-/l*N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lift-*.f32N/A
associate-*l*N/A
associate-/r*N/A
metadata-evalN/A
metadata-evalN/A
associate-/r*N/A
associate-*l*N/A
lift-*.f32N/A
associate-*l*N/A
lift-*.f32N/A
lift-*.f32N/A
Applied rewrites96.5%
(FPCore (s r)
:precision binary32
(let* ((t_0 (/ r (PI))))
(+
(/ (* 0.25 (exp (/ (- r) s))) (* (* (* 2.0 (PI)) s) r))
(/
(-
(/
(-
(/ -0.041666666666666664 (PI))
(/
(fma
0.0007716049382716049
(* (/ t_0 s) r)
(* -0.006944444444444444 t_0))
s))
s)
(/ -0.125 (* (PI) r)))
s))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{r}{\mathsf{PI}\left(\right)}\\
\frac{0.25 \cdot e^{\frac{-r}{s}}}{\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r} + \frac{\frac{\frac{-0.041666666666666664}{\mathsf{PI}\left(\right)} - \frac{\mathsf{fma}\left(0.0007716049382716049, \frac{t\_0}{s} \cdot r, -0.006944444444444444 \cdot t\_0\right)}{s}}{s} - \frac{-0.125}{\mathsf{PI}\left(\right) \cdot r}}{s}
\end{array}
\end{array}
Initial program 99.6%
Taylor expanded in s around -inf
Applied rewrites7.2%
(FPCore (s r)
:precision binary32
(let* ((t_0 (/ r (PI))))
(+
(/ (/ 0.125 (exp (/ r s))) (* (* (PI) s) r))
(/
(+
(/
(-
(/ -0.041666666666666664 (PI))
(/
(fma
(* r (/ t_0 s))
0.0007716049382716049
(* -0.006944444444444444 t_0))
s))
s)
(/ 0.125 (* (PI) r)))
s))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{r}{\mathsf{PI}\left(\right)}\\
\frac{\frac{0.125}{e^{\frac{r}{s}}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r} + \frac{\frac{\frac{-0.041666666666666664}{\mathsf{PI}\left(\right)} - \frac{\mathsf{fma}\left(r \cdot \frac{t\_0}{s}, 0.0007716049382716049, -0.006944444444444444 \cdot t\_0\right)}{s}}{s} + \frac{0.125}{\mathsf{PI}\left(\right) \cdot r}}{s}
\end{array}
\end{array}
Initial program 99.6%
lift-/.f32N/A
frac-2negN/A
div-invN/A
lift-neg.f32N/A
remove-double-negN/A
lower-*.f32N/A
lift-*.f32N/A
distribute-lft-neg-inN/A
associate-/r*N/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower-/.f32N/A
metadata-eval99.6
Applied rewrites99.6%
Taylor expanded in s around 0
associate-*r/N/A
lower-/.f32N/A
mul-1-negN/A
exp-negN/A
associate-*r/N/A
metadata-evalN/A
lower-/.f32N/A
lower-exp.f32N/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3299.6
Applied rewrites99.6%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-*.f32N/A
lift-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-*.f3299.6
Applied rewrites99.6%
Taylor expanded in s around -inf
Applied rewrites6.1%
(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 99.6%
lift-/.f32N/A
frac-2negN/A
div-invN/A
lift-neg.f32N/A
remove-double-negN/A
lower-*.f32N/A
lift-*.f32N/A
distribute-lft-neg-inN/A
associate-/r*N/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower-/.f32N/A
metadata-eval99.6
Applied rewrites99.6%
Taylor expanded in s around -inf
associate-*r/N/A
Applied rewrites10.0%
(FPCore (s r) :precision binary32 (let* ((t_0 (sqrt (PI)))) (/ 0.25 (* t_0 (* t_0 (* s r))))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{\mathsf{PI}\left(\right)}\\
\frac{0.25}{t\_0 \cdot \left(t\_0 \cdot \left(s \cdot r\right)\right)}
\end{array}
\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.f328.9
Applied rewrites8.9%
Applied rewrites8.9%
Applied rewrites8.9%
(FPCore (s r) :precision binary32 (/ 1.0 (/ r (/ 0.25 (* (PI) s)))))
\begin{array}{l}
\\
\frac{1}{\frac{r}{\frac{0.25}{\mathsf{PI}\left(\right) \cdot s}}}
\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.f328.9
Applied rewrites8.9%
Applied rewrites8.9%
(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 99.6%
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.f328.9
Applied rewrites8.9%
Applied rewrites8.9%
(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 99.6%
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.f328.9
Applied rewrites8.9%
Applied rewrites8.9%
(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.f328.9
Applied rewrites8.9%
Applied rewrites8.9%
Applied rewrites8.9%
(FPCore (s r) :precision binary32 (/ 0.25 (* (* r (PI)) s)))
\begin{array}{l}
\\
\frac{0.25}{\left(r \cdot \mathsf{PI}\left(\right)\right) \cdot s}
\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.f328.9
Applied rewrites8.9%
Applied rewrites8.9%
Applied rewrites8.9%
herbie shell --seed 2024320
(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))))