
(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 (fma (/ (exp (/ (/ r -3.0) s)) (* (* (* 6.0 (PI)) s) r)) 0.75 (* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r)))))
\begin{array}{l}
\\
\mathsf{fma}\left(\frac{e^{\frac{\frac{r}{-3}}{s}}}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}, 0.75, 0.125 \cdot \frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r}\right)
\end{array}
Initial program 99.6%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites99.6%
(FPCore (s r) :precision binary32 (/ (fma (/ (exp (/ (/ r -3.0) s)) (PI)) 0.125 (* (/ (exp (/ (- r) s)) (PI)) 0.125)) (* s r)))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{e^{\frac{\frac{r}{-3}}{s}}}{\mathsf{PI}\left(\right)}, 0.125, \frac{e^{\frac{-r}{s}}}{\mathsf{PI}\left(\right)} \cdot 0.125\right)}{s \cdot r}
\end{array}
Initial program 99.6%
lift-+.f32N/A
+-commutativeN/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 rewrites99.6%
(FPCore (s r) :precision binary32 (/ (/ (* 0.125 (+ (exp (/ (- r) s)) (exp (/ (/ r -3.0) s)))) (* (PI) s)) r))
\begin{array}{l}
\\
\frac{\frac{0.125 \cdot \left(e^{\frac{-r}{s}} + e^{\frac{\frac{r}{-3}}{s}}\right)}{\mathsf{PI}\left(\right) \cdot s}}{r}
\end{array}
Initial program 99.6%
Applied rewrites99.5%
lift-fma.f32N/A
lift-*.f32N/A
distribute-lft-outN/A
lift-/.f32N/A
associate-*l/N/A
lower-/.f32N/A
lower-*.f32N/A
lower-+.f3299.5
Applied rewrites99.5%
(FPCore (s r)
:precision binary32
(fma
(/
(+
(/
(-
(/
(fma
(/ 0.00102880658436214 (PI))
(/ (* r r) s)
(* -0.009259259259259259 (/ r (PI))))
(- s))
(/ 0.05555555555555555 (PI)))
s)
(/ 0.16666666666666666 (* (PI) r)))
s)
0.75
(* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r)))))\begin{array}{l}
\\
\mathsf{fma}\left(\frac{\frac{\frac{\mathsf{fma}\left(\frac{0.00102880658436214}{\mathsf{PI}\left(\right)}, \frac{r \cdot r}{s}, -0.009259259259259259 \cdot \frac{r}{\mathsf{PI}\left(\right)}\right)}{-s} - \frac{0.05555555555555555}{\mathsf{PI}\left(\right)}}{s} + \frac{0.16666666666666666}{\mathsf{PI}\left(\right) \cdot r}}{s}, 0.75, 0.125 \cdot \frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r}\right)
\end{array}
Initial program 99.6%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites99.6%
Taylor expanded in s around inf
+-commutativeN/A
lower-fma.f32N/A
lower-/.f3210.7
Applied rewrites10.7%
Taylor expanded in s around -inf
mul-1-negN/A
distribute-neg-frac2N/A
lower-/.f32N/A
Applied rewrites11.6%
Final simplification11.6%
(FPCore (s r)
:precision binary32
(+
(/ (* 0.125 (exp (/ (- r) s))) (* (* (PI) s) r))
(/
(fma
(fma
(/ (+ 0.041666666666666664 (/ (* -0.004629629629629629 r) s)) (* s s))
r
(/ -0.25 s))
r
0.75)
(* (* (* 6.0 (PI)) s) r))))\begin{array}{l}
\\
\frac{0.125 \cdot e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r} + \frac{\mathsf{fma}\left(\mathsf{fma}\left(\frac{0.041666666666666664 + \frac{-0.004629629629629629 \cdot r}{s}}{s \cdot s}, r, \frac{-0.25}{s}\right), r, 0.75\right)}{\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-/r*N/A
lift-/.f32N/A
lower-/.f3299.6
Applied rewrites99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lift-*.f32N/A
associate-/r*N/A
metadata-evalN/A
times-fracN/A
lift-*.f32N/A
lower-/.f32N/A
lower-*.f3299.6
Applied rewrites99.6%
Taylor expanded in r around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites11.6%
(FPCore (s r)
:precision binary32
(fma
(/
(fma
(fma (/ 0.05555555555555555 s) (/ r s) (/ -0.3333333333333333 s))
r
1.0)
(* (* (* 6.0 (PI)) s) r))
0.75
(* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r)))))\begin{array}{l}
\\
\mathsf{fma}\left(\frac{\mathsf{fma}\left(\mathsf{fma}\left(\frac{0.05555555555555555}{s}, \frac{r}{s}, \frac{-0.3333333333333333}{s}\right), r, 1\right)}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}, 0.75, 0.125 \cdot \frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r}\right)
\end{array}
Initial program 99.6%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites99.6%
Taylor expanded in r around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
fp-cancel-sub-sign-invN/A
associate-*r/N/A
unpow2N/A
times-fracN/A
lower-fma.f32N/A
lower-/.f32N/A
lower-/.f32N/A
metadata-evalN/A
associate-*r/N/A
metadata-evalN/A
lower-/.f3211.5
Applied rewrites11.5%
(FPCore (s r)
:precision binary32
(fma
(/
(fma
(- (* (/ r (* s s)) 0.05555555555555555) (/ 0.3333333333333333 s))
r
1.0)
(* (* (* 6.0 (PI)) s) r))
0.75
(* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r)))))\begin{array}{l}
\\
\mathsf{fma}\left(\frac{\mathsf{fma}\left(\frac{r}{s \cdot s} \cdot 0.05555555555555555 - \frac{0.3333333333333333}{s}, r, 1\right)}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}, 0.75, 0.125 \cdot \frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r}\right)
\end{array}
Initial program 99.6%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites99.6%
Taylor expanded in s around inf
+-commutativeN/A
lower-fma.f32N/A
lower-/.f3210.7
Applied rewrites10.7%
Taylor expanded in r around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-/.f32N/A
unpow2N/A
lower-*.f32N/A
associate-*r/N/A
metadata-evalN/A
lower-/.f3211.5
Applied rewrites11.5%
(FPCore (s r)
:precision binary32
(fma
(/
(-
1.0
(/ (fma 0.3333333333333333 r (* (* r (/ r s)) -0.05555555555555555)) s))
(* (* (* 6.0 (PI)) s) r))
0.75
(* 0.125 (/ (exp (/ (- r) s)) (* (* (PI) s) r)))))\begin{array}{l}
\\
\mathsf{fma}\left(\frac{1 - \frac{\mathsf{fma}\left(0.3333333333333333, r, \left(r \cdot \frac{r}{s}\right) \cdot -0.05555555555555555\right)}{s}}{\left(\left(6 \cdot \mathsf{PI}\left(\right)\right) \cdot s\right) \cdot r}, 0.75, 0.125 \cdot \frac{e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r}\right)
\end{array}
Initial program 99.6%
lift-+.f32N/A
+-commutativeN/A
lift-/.f32N/A
lift-*.f32N/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites99.6%
Taylor expanded in s around -inf
fp-cancel-sign-sub-invN/A
metadata-evalN/A
*-lft-identityN/A
lower--.f32N/A
lower-/.f32N/A
+-commutativeN/A
lower-fma.f32N/A
*-commutativeN/A
lower-*.f32N/A
unpow2N/A
associate-/l*N/A
lower-*.f32N/A
lower-/.f3211.5
Applied rewrites11.5%
(FPCore (s r) :precision binary32 (+ (/ (* 0.125 (exp (/ (- r) s))) (* (* (PI) s) r)) (/ (fma (/ (+ -0.25 (/ (* 0.041666666666666664 r) s)) s) r 0.75) (* (* (* 6.0 (PI)) s) r))))
\begin{array}{l}
\\
\frac{0.125 \cdot e^{\frac{-r}{s}}}{\left(\mathsf{PI}\left(\right) \cdot s\right) \cdot r} + \frac{\mathsf{fma}\left(\frac{-0.25 + \frac{0.041666666666666664 \cdot r}{s}}{s}, r, 0.75\right)}{\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-/r*N/A
lift-/.f32N/A
lower-/.f3299.6
Applied rewrites99.6%
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
times-fracN/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lift-*.f32N/A
associate-/r*N/A
metadata-evalN/A
times-fracN/A
lift-*.f32N/A
lower-/.f32N/A
lower-*.f3299.6
Applied rewrites99.6%
Taylor expanded in r around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
fp-cancel-sub-sign-invN/A
+-commutativeN/A
metadata-evalN/A
associate-*r/N/A
metadata-evalN/A
associate-*r/N/A
unpow2N/A
associate-/r*N/A
div-add-revN/A
lower-/.f32N/A
lower-+.f32N/A
lower-/.f32N/A
lower-*.f3211.5
Applied rewrites11.5%
(FPCore (s r) :precision binary32 (/ (- 1.5 (/ (fma r 1.0 (/ (* (* (- r) r) 0.4166666666666667) s)) s)) (* (* (* (PI) 6.0) s) r)))
\begin{array}{l}
\\
\frac{1.5 - \frac{\mathsf{fma}\left(r, 1, \frac{\left(\left(-r\right) \cdot r\right) \cdot 0.4166666666666667}{s}\right)}{s}}{\left(\left(\mathsf{PI}\left(\right) \cdot 6\right) \cdot s\right) \cdot r}
\end{array}
Initial program 99.6%
Taylor expanded in s around inf
Applied rewrites9.9%
lift-+.f32N/A
lift-/.f32N/A
lift-/.f32N/A
frac-addN/A
associate-/r*N/A
lower-/.f32N/A
Applied rewrites9.9%
Taylor expanded in s around -inf
fp-cancel-sign-sub-invN/A
metadata-evalN/A
*-lft-identityN/A
lower--.f32N/A
lower-/.f32N/A
Applied rewrites10.9%
Final simplification10.9%
(FPCore (s r) :precision binary32 (/ (fma (- (* 0.4166666666666667 (/ r (* s s))) (/ 1.0 s)) r 1.5) (* (* (* (PI) 6.0) s) r)))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(0.4166666666666667 \cdot \frac{r}{s \cdot s} - \frac{1}{s}, r, 1.5\right)}{\left(\left(\mathsf{PI}\left(\right) \cdot 6\right) \cdot s\right) \cdot r}
\end{array}
Initial program 99.6%
Taylor expanded in s around inf
Applied rewrites9.9%
lift-+.f32N/A
lift-/.f32N/A
lift-/.f32N/A
frac-addN/A
associate-/r*N/A
lower-/.f32N/A
Applied rewrites9.9%
Taylor expanded in r around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lower--.f32N/A
lower-*.f32N/A
lower-/.f32N/A
unpow2N/A
lower-*.f32N/A
lower-/.f3210.9
Applied rewrites10.9%
(FPCore (s r) :precision binary32 (/ (- 1.5 (/ r s)) (* (* (* (PI) 6.0) s) r)))
\begin{array}{l}
\\
\frac{1.5 - \frac{r}{s}}{\left(\left(\mathsf{PI}\left(\right) \cdot 6\right) \cdot s\right) \cdot r}
\end{array}
Initial program 99.6%
Taylor expanded in s around inf
Applied rewrites9.9%
lift-+.f32N/A
lift-/.f32N/A
lift-/.f32N/A
frac-addN/A
associate-/r*N/A
lower-/.f32N/A
Applied rewrites9.9%
Taylor expanded in r around 0
fp-cancel-sign-sub-invN/A
metadata-evalN/A
*-lft-identityN/A
lower--.f32N/A
lower-/.f3210.1
Applied rewrites10.1%
(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
*-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.f329.8
Applied rewrites9.8%
Applied rewrites9.8%
Applied rewrites9.8%
herbie shell --seed 2025011
(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))))