
(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 13 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)))) (* (* (* (* r s) 6.0) (cbrt (* (PI) (PI)))) (cbrt (PI))))))
\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}}}{\left(\left(\left(r \cdot s\right) \cdot 6\right) \cdot \sqrt[3]{\mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)}\right) \cdot \sqrt[3]{\mathsf{PI}\left(\right)}}
\end{array}
Initial program 99.2%
Taylor expanded in s around 0
lower-*.f32N/A
lower-/.f3299.2
Applied rewrites99.2%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*l*N/A
*-commutativeN/A
lift-*.f32N/A
lift-PI.f32N/A
add-cube-cbrtN/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
lift-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
pow2N/A
lower-pow.f32N/A
lift-PI.f32N/A
lower-cbrt.f32N/A
lift-PI.f32N/A
Applied rewrites99.2%
Taylor expanded in s around 0
associate-*r*N/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-*.f32N/A
lower-cbrt.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f3299.2
Applied rewrites99.2%
(FPCore (s r)
:precision binary32
(let* ((t_0 (exp (/ (- r) s))))
(if (<=
(+
(/ (* 0.25 t_0) (* (* (* 2.0 (PI)) s) r))
(/ (* 0.75 (exp (/ (- r) (* 3.0 s)))) (* (* (* 6.0 (PI)) s) r)))
4.0000000467443897e-7)
(/
(fma (/ t_0 (PI)) 0.125 (* (/ (exp (/ (/ r -3.0) s)) (PI)) 0.125))
(* s r))
(/
(+
(/
(-
(/ (* 0.06944444444444445 (/ r (PI))) s)
(/ 0.16666666666666666 (PI)))
s)
(/ 0.25 (* (PI) r)))
s))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := e^{\frac{-r}{s}}\\
\mathbf{if}\;\frac{0.25 \cdot t\_0}{\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 4.0000000467443897 \cdot 10^{-7}:\\
\;\;\;\;\frac{\mathsf{fma}\left(\frac{t\_0}{\mathsf{PI}\left(\right)}, 0.125, \frac{e^{\frac{\frac{r}{-3}}{s}}}{\mathsf{PI}\left(\right)} \cdot 0.125\right)}{s \cdot r}\\
\mathbf{else}:\\
\;\;\;\;\frac{\frac{\frac{0.06944444444444445 \cdot \frac{r}{\mathsf{PI}\left(\right)}}{s} - \frac{0.16666666666666666}{\mathsf{PI}\left(\right)}}{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))) < 4.00000005e-7Initial program 99.4%
lift-+.f32N/A
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-/r*N/A
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-/r*N/A
Applied rewrites98.1%
if 4.00000005e-7 < (+.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 97.9%
Taylor expanded in s around -inf
mul-1-negN/A
distribute-neg-frac2N/A
lower-/.f32N/A
Applied rewrites67.3%
Final simplification93.8%
(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)))
2.0000000072549875e-15)
(/
(fma
(/ (fma -0.25 (/ r s) 0.25) (* (* (PI) 2.0) s))
r
(* r (* (exp (/ (/ r s) -3.0)) (/ 0.125 (* (PI) s)))))
(* r r))
(/
(+
(/
(- (/ (* 0.06944444444444445 (/ r (PI))) s) (/ 0.16666666666666666 (PI)))
s)
(/ 0.25 (* (PI) r)))
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 2.0000000072549875 \cdot 10^{-15}:\\
\;\;\;\;\frac{\mathsf{fma}\left(\frac{\mathsf{fma}\left(-0.25, \frac{r}{s}, 0.25\right)}{\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot s}, r, r \cdot \left(e^{\frac{\frac{r}{s}}{-3}} \cdot \frac{0.125}{\mathsf{PI}\left(\right) \cdot s}\right)\right)}{r \cdot r}\\
\mathbf{else}:\\
\;\;\;\;\frac{\frac{\frac{0.06944444444444445 \cdot \frac{r}{\mathsf{PI}\left(\right)}}{s} - \frac{0.16666666666666666}{\mathsf{PI}\left(\right)}}{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))) < 2.00000001e-15Initial program 99.5%
Taylor expanded in s around inf
+-commutativeN/A
lower-fma.f32N/A
lower-/.f324.6
Applied rewrites4.6%
Applied rewrites99.4%
if 2.00000001e-15 < (+.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 97.7%
Taylor expanded in s around -inf
mul-1-negN/A
distribute-neg-frac2N/A
lower-/.f32N/A
Applied rewrites63.4%
Final simplification93.9%
(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}}}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}
\end{array}
Initial program 99.2%
Taylor expanded in s around 0
lower-*.f32N/A
lower-/.f3299.2
Applied rewrites99.2%
(FPCore (s r) :precision binary32 (+ (* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r))) (/ (* 0.75 (exp (/ (- r) (* 3.0 s)))) (* (* (* 6.0 (PI)) s) r))))
\begin{array}{l}
\\
0.125 \cdot \frac{e^{\frac{-r}{s}}}{\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 99.2%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
associate-*l*N/A
times-fracN/A
lower-*.f32N/A
metadata-evalN/A
lower-/.f32N/A
lower-*.f32N/A
lower-*.f3299.2
Applied rewrites99.2%
(FPCore (s r) :precision binary32 (+ (* 0.125 (/ (exp (/ (- r) s)) (* (PI) (* s r)))) (/ (* 0.75 (exp (/ (- r) (* 3.0 s)))) (* (* (* 6.0 (PI)) s) r))))
\begin{array}{l}
\\
0.125 \cdot \frac{e^{\frac{-r}{s}}}{\mathsf{PI}\left(\right) \cdot \left(s \cdot r\right)} + \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 99.2%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lift-*.f32N/A
associate-*l*N/A
times-fracN/A
lower-*.f32N/A
metadata-evalN/A
lower-/.f32N/A
lower-*.f32N/A
lower-*.f3299.2
Applied rewrites99.2%
(FPCore (s r)
:precision binary32
(let* ((t_0 (* (* (PI) s) r)))
(+
(* 0.125 (/ (exp (/ (/ r -3.0) s)) t_0))
(* 0.125 (/ (exp (/ (- r) s)) t_0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r\\
0.125 \cdot \frac{e^{\frac{\frac{r}{-3}}{s}}}{t\_0} + 0.125 \cdot \frac{e^{\frac{-r}{s}}}{t\_0}
\end{array}
\end{array}
Initial program 99.2%
lift-+.f32N/A
+-commutativeN/A
lower-+.f3299.2
Applied rewrites99.1%
(FPCore (s r)
:precision binary32
(/
(+
(/
(- (/ (* 0.06944444444444445 (/ r (PI))) s) (/ 0.16666666666666666 (PI)))
s)
(/ 0.25 (* (PI) r)))
s))\begin{array}{l}
\\
\frac{\frac{\frac{0.06944444444444445 \cdot \frac{r}{\mathsf{PI}\left(\right)}}{s} - \frac{0.16666666666666666}{\mathsf{PI}\left(\right)}}{s} + \frac{0.25}{\mathsf{PI}\left(\right) \cdot r}}{s}
\end{array}
Initial program 99.2%
Taylor expanded in s around -inf
mul-1-negN/A
distribute-neg-frac2N/A
lower-/.f32N/A
Applied rewrites12.6%
Final simplification12.6%
(FPCore (s r) :precision binary32 (/ (/ (+ (/ -0.25 r) (/ 0.16666666666666666 s)) (- (PI))) s))
\begin{array}{l}
\\
\frac{\frac{\frac{-0.25}{r} + \frac{0.16666666666666666}{s}}{-\mathsf{PI}\left(\right)}}{s}
\end{array}
Initial program 99.2%
Taylor expanded in s around 0
lower-*.f32N/A
lower-/.f3299.2
Applied rewrites99.2%
Taylor expanded in s around -inf
mul-1-negN/A
distribute-neg-frac2N/A
lower-/.f32N/A
Applied rewrites11.3%
Final simplification11.3%
(FPCore (s r) :precision binary32 (/ (/ 0.25 (* (PI) s)) r))
\begin{array}{l}
\\
\frac{\frac{0.25}{\mathsf{PI}\left(\right) \cdot s}}{r}
\end{array}
Initial program 99.2%
Taylor expanded in s around inf
*-commutativeN/A
associate-/r*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.f3210.9
Applied rewrites10.9%
(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 99.2%
Taylor expanded in s around inf
*-commutativeN/A
associate-/r*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.f3210.9
Applied rewrites10.9%
Applied rewrites10.9%
(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 99.2%
Taylor expanded in s around inf
*-commutativeN/A
associate-/r*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.f3210.9
Applied rewrites10.9%
Applied rewrites10.9%
Applied rewrites10.9%
(FPCore (s r) :precision binary32 (/ 0.25 (* (* r s) (PI))))
\begin{array}{l}
\\
\frac{0.25}{\left(r \cdot s\right) \cdot \mathsf{PI}\left(\right)}
\end{array}
Initial program 99.2%
Taylor expanded in s around inf
*-commutativeN/A
associate-/r*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.f3210.9
Applied rewrites10.9%
Applied rewrites10.9%
Applied rewrites10.9%
herbie shell --seed 2024337
(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))))