
(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))))
float code(float s, float r) {
return ((0.25f * expf((-r / s))) / (((2.0f * ((float) M_PI)) * s) * r)) + ((0.75f * expf((-r / (3.0f * s)))) / (((6.0f * ((float) M_PI)) * s) * r));
}
function code(s, r) return Float32(Float32(Float32(Float32(0.25) * exp(Float32(Float32(-r) / s))) / Float32(Float32(Float32(Float32(2.0) * Float32(pi)) * s) * r)) + Float32(Float32(Float32(0.75) * exp(Float32(Float32(-r) / Float32(Float32(3.0) * s)))) / Float32(Float32(Float32(Float32(6.0) * Float32(pi)) * s) * r))) end
function tmp = code(s, r) tmp = ((single(0.25) * exp((-r / s))) / (((single(2.0) * single(pi)) * s) * r)) + ((single(0.75) * exp((-r / (single(3.0) * s)))) / (((single(6.0) * single(pi)) * s) * r)); end
\begin{array}{l}
\\
\frac{0.25 \cdot e^{\frac{-r}{s}}}{\left(\left(2 \cdot \pi\right) \cdot s\right) \cdot r} + \frac{0.75 \cdot e^{\frac{-r}{3 \cdot s}}}{\left(\left(6 \cdot \pi\right) \cdot s\right) \cdot r}
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 11 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))))
float code(float s, float r) {
return ((0.25f * expf((-r / s))) / (((2.0f * ((float) M_PI)) * s) * r)) + ((0.75f * expf((-r / (3.0f * s)))) / (((6.0f * ((float) M_PI)) * s) * r));
}
function code(s, r) return Float32(Float32(Float32(Float32(0.25) * exp(Float32(Float32(-r) / s))) / Float32(Float32(Float32(Float32(2.0) * Float32(pi)) * s) * r)) + Float32(Float32(Float32(0.75) * exp(Float32(Float32(-r) / Float32(Float32(3.0) * s)))) / Float32(Float32(Float32(Float32(6.0) * Float32(pi)) * s) * r))) end
function tmp = code(s, r) tmp = ((single(0.25) * exp((-r / s))) / (((single(2.0) * single(pi)) * s) * r)) + ((single(0.75) * exp((-r / (single(3.0) * s)))) / (((single(6.0) * single(pi)) * s) * r)); end
\begin{array}{l}
\\
\frac{0.25 \cdot e^{\frac{-r}{s}}}{\left(\left(2 \cdot \pi\right) \cdot s\right) \cdot r} + \frac{0.75 \cdot e^{\frac{-r}{3 \cdot s}}}{\left(\left(6 \cdot \pi\right) \cdot s\right) \cdot r}
\end{array}
(FPCore (s r) :precision binary32 (/ (+ (/ (* 0.125 (exp (/ r (- s)))) (* r PI)) (* 0.125 (/ (pow E (* (/ r s) -0.3333333333333333)) (* r PI)))) s))
float code(float s, float r) {
return (((0.125f * expf((r / -s))) / (r * ((float) M_PI))) + (0.125f * (powf(((float) M_E), ((r / s) * -0.3333333333333333f)) / (r * ((float) M_PI))))) / s;
}
function code(s, r) return Float32(Float32(Float32(Float32(Float32(0.125) * exp(Float32(r / Float32(-s)))) / Float32(r * Float32(pi))) + Float32(Float32(0.125) * Float32((Float32(exp(1)) ^ Float32(Float32(r / s) * Float32(-0.3333333333333333))) / Float32(r * Float32(pi))))) / s) end
function tmp = code(s, r) tmp = (((single(0.125) * exp((r / -s))) / (r * single(pi))) + (single(0.125) * ((single(2.71828182845904523536) ^ ((r / s) * single(-0.3333333333333333))) / (r * single(pi))))) / s; end
\begin{array}{l}
\\
\frac{\frac{0.125 \cdot e^{\frac{r}{-s}}}{r \cdot \pi} + 0.125 \cdot \frac{{e}^{\left(\frac{r}{s} \cdot -0.3333333333333333\right)}}{r \cdot \pi}}{s}
\end{array}
Initial program 99.3%
+-commutative99.3%
times-frac99.2%
fma-define99.3%
associate-*l*99.2%
associate-/r*99.2%
metadata-eval99.2%
*-commutative99.2%
neg-mul-199.2%
times-frac99.3%
metadata-eval99.3%
times-frac99.3%
Simplified99.3%
Taylor expanded in s around 0 99.3%
*-un-lft-identity99.3%
exp-prod99.4%
*-commutative99.4%
Applied egg-rr99.4%
exp-1-e99.4%
Simplified99.4%
associate-*r/99.4%
mul-1-neg99.4%
distribute-frac-neg299.4%
Applied egg-rr99.4%
(FPCore (s r) :precision binary32 (* 0.125 (/ (+ (/ (exp (/ r (- s))) r) (/ (pow E (* (/ r s) -0.3333333333333333)) r)) (* s PI))))
float code(float s, float r) {
return 0.125f * (((expf((r / -s)) / r) + (powf(((float) M_E), ((r / s) * -0.3333333333333333f)) / r)) / (s * ((float) M_PI)));
}
function code(s, r) return Float32(Float32(0.125) * Float32(Float32(Float32(exp(Float32(r / Float32(-s))) / r) + Float32((Float32(exp(1)) ^ Float32(Float32(r / s) * Float32(-0.3333333333333333))) / r)) / Float32(s * Float32(pi)))) end
function tmp = code(s, r) tmp = single(0.125) * (((exp((r / -s)) / r) + ((single(2.71828182845904523536) ^ ((r / s) * single(-0.3333333333333333))) / r)) / (s * single(pi))); end
\begin{array}{l}
\\
0.125 \cdot \frac{\frac{e^{\frac{r}{-s}}}{r} + \frac{{e}^{\left(\frac{r}{s} \cdot -0.3333333333333333\right)}}{r}}{s \cdot \pi}
\end{array}
Initial program 99.3%
Simplified98.9%
add-sqr-sqrt98.9%
sqrt-unprod98.6%
pow-prod-down98.5%
prod-exp98.9%
metadata-eval98.9%
Applied egg-rr98.9%
Taylor expanded in s around 0 98.9%
Simplified99.2%
*-un-lft-identity99.3%
exp-prod99.4%
*-commutative99.4%
Applied egg-rr99.3%
exp-1-e99.4%
Simplified99.3%
(FPCore (s r) :precision binary32 (* 0.125 (/ (+ (exp (/ r (- s))) (exp (* (/ r s) -0.3333333333333333))) (* r (* s PI)))))
float code(float s, float r) {
return 0.125f * ((expf((r / -s)) + expf(((r / s) * -0.3333333333333333f))) / (r * (s * ((float) M_PI))));
}
function code(s, r) return Float32(Float32(0.125) * Float32(Float32(exp(Float32(r / Float32(-s))) + exp(Float32(Float32(r / s) * Float32(-0.3333333333333333)))) / Float32(r * Float32(s * Float32(pi))))) end
function tmp = code(s, r) tmp = single(0.125) * ((exp((r / -s)) + exp(((r / s) * single(-0.3333333333333333)))) / (r * (s * single(pi)))); end
\begin{array}{l}
\\
0.125 \cdot \frac{e^{\frac{r}{-s}} + e^{\frac{r}{s} \cdot -0.3333333333333333}}{r \cdot \left(s \cdot \pi\right)}
\end{array}
Initial program 99.3%
Simplified98.9%
add-sqr-sqrt98.9%
sqrt-unprod98.6%
pow-prod-down98.5%
prod-exp98.9%
metadata-eval98.9%
Applied egg-rr98.9%
Taylor expanded in r around inf 98.9%
neg-mul-198.9%
distribute-neg-frac298.9%
exp-sqrt99.3%
*-commutative99.3%
associate-/l*99.3%
metadata-eval99.3%
*-commutative99.3%
Simplified99.3%
Final simplification99.3%
(FPCore (s r) :precision binary32 (/ 0.25 (* s (log1p (expm1 (* r PI))))))
float code(float s, float r) {
return 0.25f / (s * log1pf(expm1f((r * ((float) M_PI)))));
}
function code(s, r) return Float32(Float32(0.25) / Float32(s * log1p(expm1(Float32(r * Float32(pi)))))) end
\begin{array}{l}
\\
\frac{0.25}{s \cdot \mathsf{log1p}\left(\mathsf{expm1}\left(r \cdot \pi\right)\right)}
\end{array}
Initial program 99.3%
Simplified98.9%
Taylor expanded in s around inf 8.4%
*-commutative8.4%
associate-*l*8.4%
*-commutative8.4%
Simplified8.4%
log1p-expm1-u43.4%
Applied egg-rr43.4%
(FPCore (s r) :precision binary32 (/ 0.25 (log1p (expm1 (* r (* s PI))))))
float code(float s, float r) {
return 0.25f / log1pf(expm1f((r * (s * ((float) M_PI)))));
}
function code(s, r) return Float32(Float32(0.25) / log1p(expm1(Float32(r * Float32(s * Float32(pi)))))) end
\begin{array}{l}
\\
\frac{0.25}{\mathsf{log1p}\left(\mathsf{expm1}\left(r \cdot \left(s \cdot \pi\right)\right)\right)}
\end{array}
Initial program 99.3%
Simplified98.9%
Taylor expanded in s around inf 8.4%
log1p-expm1-u12.0%
*-commutative12.0%
Applied egg-rr12.0%
Final simplification12.0%
(FPCore (s r)
:precision binary32
(+
(/ (* (exp (/ r (- s))) 0.25) (* r (* s (* PI 2.0))))
(/
(-
(/ (/ 0.125 r) PI)
(/
(- (/ 0.041666666666666664 PI) (* (/ r (* s PI)) 0.006944444444444444))
s))
s)))
float code(float s, float r) {
return ((expf((r / -s)) * 0.25f) / (r * (s * (((float) M_PI) * 2.0f)))) + ((((0.125f / r) / ((float) M_PI)) - (((0.041666666666666664f / ((float) M_PI)) - ((r / (s * ((float) M_PI))) * 0.006944444444444444f)) / s)) / s);
}
function code(s, r) return Float32(Float32(Float32(exp(Float32(r / Float32(-s))) * Float32(0.25)) / Float32(r * Float32(s * Float32(Float32(pi) * Float32(2.0))))) + Float32(Float32(Float32(Float32(Float32(0.125) / r) / Float32(pi)) - Float32(Float32(Float32(Float32(0.041666666666666664) / Float32(pi)) - Float32(Float32(r / Float32(s * Float32(pi))) * Float32(0.006944444444444444))) / s)) / s)) end
function tmp = code(s, r) tmp = ((exp((r / -s)) * single(0.25)) / (r * (s * (single(pi) * single(2.0))))) + ((((single(0.125) / r) / single(pi)) - (((single(0.041666666666666664) / single(pi)) - ((r / (s * single(pi))) * single(0.006944444444444444))) / s)) / s); end
\begin{array}{l}
\\
\frac{e^{\frac{r}{-s}} \cdot 0.25}{r \cdot \left(s \cdot \left(\pi \cdot 2\right)\right)} + \frac{\frac{\frac{0.125}{r}}{\pi} - \frac{\frac{0.041666666666666664}{\pi} - \frac{r}{s \cdot \pi} \cdot 0.006944444444444444}{s}}{s}
\end{array}
Initial program 99.3%
Taylor expanded in r around 0 99.3%
add-exp-log99.1%
associate-*l*99.1%
*-commutative99.1%
Applied egg-rr99.1%
Taylor expanded in s around -inf 9.7%
mul-1-neg9.7%
mul-1-neg9.7%
*-commutative9.7%
associate-*r/9.7%
metadata-eval9.7%
associate-*r/9.7%
metadata-eval9.7%
associate-/r*9.7%
Simplified9.7%
Final simplification9.7%
(FPCore (s r) :precision binary32 (/ (+ (* 0.125 (+ (/ (- (/ -1.0 PI) (* (/ r (* s PI)) -0.5)) s) (/ 1.0 (* r PI)))) (* 0.125 (/ (exp (* (/ r s) -0.3333333333333333)) (* r PI)))) s))
float code(float s, float r) {
return ((0.125f * ((((-1.0f / ((float) M_PI)) - ((r / (s * ((float) M_PI))) * -0.5f)) / s) + (1.0f / (r * ((float) M_PI))))) + (0.125f * (expf(((r / s) * -0.3333333333333333f)) / (r * ((float) M_PI))))) / s;
}
function code(s, r) return Float32(Float32(Float32(Float32(0.125) * Float32(Float32(Float32(Float32(Float32(-1.0) / Float32(pi)) - Float32(Float32(r / Float32(s * Float32(pi))) * Float32(-0.5))) / s) + Float32(Float32(1.0) / Float32(r * Float32(pi))))) + Float32(Float32(0.125) * Float32(exp(Float32(Float32(r / s) * Float32(-0.3333333333333333))) / Float32(r * Float32(pi))))) / s) end
function tmp = code(s, r) tmp = ((single(0.125) * ((((single(-1.0) / single(pi)) - ((r / (s * single(pi))) * single(-0.5))) / s) + (single(1.0) / (r * single(pi))))) + (single(0.125) * (exp(((r / s) * single(-0.3333333333333333))) / (r * single(pi))))) / s; end
\begin{array}{l}
\\
\frac{0.125 \cdot \left(\frac{\frac{-1}{\pi} - \frac{r}{s \cdot \pi} \cdot -0.5}{s} + \frac{1}{r \cdot \pi}\right) + 0.125 \cdot \frac{e^{\frac{r}{s} \cdot -0.3333333333333333}}{r \cdot \pi}}{s}
\end{array}
Initial program 99.3%
+-commutative99.3%
times-frac99.2%
fma-define99.3%
associate-*l*99.2%
associate-/r*99.2%
metadata-eval99.2%
*-commutative99.2%
neg-mul-199.2%
times-frac99.3%
metadata-eval99.3%
times-frac99.3%
Simplified99.3%
Taylor expanded in s around 0 99.3%
Taylor expanded in s around -inf 9.1%
Final simplification9.1%
(FPCore (s r)
:precision binary32
(*
0.125
(/
(/
(+
2.0
(*
r
(- (* (/ r (pow s 2.0)) 0.5555555555555556) (/ 1.3333333333333333 s))))
r)
(* s PI))))
float code(float s, float r) {
return 0.125f * (((2.0f + (r * (((r / powf(s, 2.0f)) * 0.5555555555555556f) - (1.3333333333333333f / s)))) / r) / (s * ((float) M_PI)));
}
function code(s, r) return Float32(Float32(0.125) * Float32(Float32(Float32(Float32(2.0) + Float32(r * Float32(Float32(Float32(r / (s ^ Float32(2.0))) * Float32(0.5555555555555556)) - Float32(Float32(1.3333333333333333) / s)))) / r) / Float32(s * Float32(pi)))) end
function tmp = code(s, r) tmp = single(0.125) * (((single(2.0) + (r * (((r / (s ^ single(2.0))) * single(0.5555555555555556)) - (single(1.3333333333333333) / s)))) / r) / (s * single(pi))); end
\begin{array}{l}
\\
0.125 \cdot \frac{\frac{2 + r \cdot \left(\frac{r}{{s}^{2}} \cdot 0.5555555555555556 - \frac{1.3333333333333333}{s}\right)}{r}}{s \cdot \pi}
\end{array}
Initial program 99.3%
Simplified98.9%
add-sqr-sqrt98.9%
sqrt-unprod98.6%
pow-prod-down98.5%
prod-exp98.9%
metadata-eval98.9%
Applied egg-rr98.9%
Taylor expanded in s around 0 98.9%
Simplified99.2%
*-commutative99.2%
exp-prod97.9%
Applied egg-rr97.9%
Taylor expanded in r around 0 9.1%
*-commutative9.1%
associate-*r/9.1%
metadata-eval9.1%
Simplified9.1%
(FPCore (s r) :precision binary32 (/ (+ (* (/ r (* PI (* s s))) 0.06944444444444445) (+ (/ 0.25 (* r PI)) (/ -0.16666666666666666 (* s PI)))) s))
float code(float s, float r) {
return (((r / (((float) M_PI) * (s * s))) * 0.06944444444444445f) + ((0.25f / (r * ((float) M_PI))) + (-0.16666666666666666f / (s * ((float) M_PI))))) / s;
}
function code(s, r) return Float32(Float32(Float32(Float32(r / Float32(Float32(pi) * Float32(s * s))) * Float32(0.06944444444444445)) + Float32(Float32(Float32(0.25) / Float32(r * Float32(pi))) + Float32(Float32(-0.16666666666666666) / Float32(s * Float32(pi))))) / s) end
function tmp = code(s, r) tmp = (((r / (single(pi) * (s * s))) * single(0.06944444444444445)) + ((single(0.25) / (r * single(pi))) + (single(-0.16666666666666666) / (s * single(pi))))) / s; end
\begin{array}{l}
\\
\frac{\frac{r}{\pi \cdot \left(s \cdot s\right)} \cdot 0.06944444444444445 + \left(\frac{0.25}{r \cdot \pi} + \frac{-0.16666666666666666}{s \cdot \pi}\right)}{s}
\end{array}
Initial program 99.3%
+-commutative99.3%
times-frac99.2%
fma-define99.3%
associate-*l*99.2%
associate-/r*99.2%
metadata-eval99.2%
*-commutative99.2%
neg-mul-199.2%
times-frac99.3%
metadata-eval99.3%
times-frac99.3%
Simplified99.3%
Taylor expanded in s around inf 9.1%
Simplified9.1%
unpow29.1%
Applied egg-rr9.1%
Final simplification9.1%
(FPCore (s r) :precision binary32 (/ 0.25 (* PI (* r s))))
float code(float s, float r) {
return 0.25f / (((float) M_PI) * (r * s));
}
function code(s, r) return Float32(Float32(0.25) / Float32(Float32(pi) * Float32(r * s))) end
function tmp = code(s, r) tmp = single(0.25) / (single(pi) * (r * s)); end
\begin{array}{l}
\\
\frac{0.25}{\pi \cdot \left(r \cdot s\right)}
\end{array}
Initial program 99.3%
Simplified98.9%
add-sqr-sqrt98.9%
sqrt-unprod98.6%
pow-prod-down98.5%
prod-exp98.9%
metadata-eval98.9%
Applied egg-rr98.9%
Taylor expanded in s around inf 8.4%
*-commutative8.4%
*-commutative8.4%
associate-*l*8.4%
Simplified8.4%
Final simplification8.4%
(FPCore (s r) :precision binary32 (/ 0.25 (* r (* s PI))))
float code(float s, float r) {
return 0.25f / (r * (s * ((float) M_PI)));
}
function code(s, r) return Float32(Float32(0.25) / Float32(r * Float32(s * Float32(pi)))) end
function tmp = code(s, r) tmp = single(0.25) / (r * (s * single(pi))); end
\begin{array}{l}
\\
\frac{0.25}{r \cdot \left(s \cdot \pi\right)}
\end{array}
Initial program 99.3%
Simplified98.9%
Taylor expanded in s around inf 8.4%
herbie shell --seed 2024113
(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))))