
(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 5 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 (+ (* (/ 0.25 (* s (* 2.0 PI))) (/ (exp (/ (- r) s)) r)) (* (/ 0.75 (* s (* PI 6.0))) (/ (exp (/ (- r) (* s 3.0))) r))))
float code(float s, float r) {
return ((0.25f / (s * (2.0f * ((float) M_PI)))) * (expf((-r / s)) / r)) + ((0.75f / (s * (((float) M_PI) * 6.0f))) * (expf((-r / (s * 3.0f))) / r));
}
function code(s, r) return Float32(Float32(Float32(Float32(0.25) / Float32(s * Float32(Float32(2.0) * Float32(pi)))) * Float32(exp(Float32(Float32(-r) / s)) / r)) + Float32(Float32(Float32(0.75) / Float32(s * Float32(Float32(pi) * Float32(6.0)))) * Float32(exp(Float32(Float32(-r) / Float32(s * Float32(3.0)))) / r))) end
function tmp = code(s, r) tmp = ((single(0.25) / (s * (single(2.0) * single(pi)))) * (exp((-r / s)) / r)) + ((single(0.75) / (s * (single(pi) * single(6.0)))) * (exp((-r / (s * single(3.0)))) / r)); end
\begin{array}{l}
\\
\frac{0.25}{s \cdot \left(2 \cdot \pi\right)} \cdot \frac{e^{\frac{-r}{s}}}{r} + \frac{0.75}{s \cdot \left(\pi \cdot 6\right)} \cdot \frac{e^{\frac{-r}{s \cdot 3}}}{r}
\end{array}
Initial program 99.5%
times-frac99.5%
fma-def99.6%
associate-*l*99.6%
associate-/r*99.6%
metadata-eval99.6%
metadata-eval99.6%
associate-/r*99.5%
associate-*l*99.5%
/-rgt-identity99.5%
fma-def99.5%
Simplified99.5%
*-commutative99.5%
add-sqr-sqrt99.5%
pow299.5%
*-commutative99.5%
Applied egg-rr99.5%
pow199.5%
*-commutative99.5%
unpow299.5%
add-sqr-sqrt99.5%
*-commutative99.5%
associate-*l*99.6%
Applied egg-rr99.6%
pow199.6%
clear-num99.5%
associate-/r/99.5%
associate-*r*99.5%
*-commutative99.5%
associate-*l*99.5%
Applied egg-rr99.5%
associate-*l/99.5%
metadata-eval99.5%
*-commutative99.5%
associate-*l*99.6%
Applied egg-rr99.6%
Final simplification99.6%
(FPCore (s r) :precision binary32 (+ (* (/ 0.25 (* s (* 2.0 PI))) (/ (exp (/ (- r) s)) r)) (* (/ (exp (/ (- r) (* s 3.0))) r) (/ (/ -0.125 s) (- PI)))))
float code(float s, float r) {
return ((0.25f / (s * (2.0f * ((float) M_PI)))) * (expf((-r / s)) / r)) + ((expf((-r / (s * 3.0f))) / r) * ((-0.125f / s) / -((float) M_PI)));
}
function code(s, r) return Float32(Float32(Float32(Float32(0.25) / Float32(s * Float32(Float32(2.0) * Float32(pi)))) * Float32(exp(Float32(Float32(-r) / s)) / r)) + Float32(Float32(exp(Float32(Float32(-r) / Float32(s * Float32(3.0)))) / r) * Float32(Float32(Float32(-0.125) / s) / Float32(-Float32(pi))))) end
function tmp = code(s, r) tmp = ((single(0.25) / (s * (single(2.0) * single(pi)))) * (exp((-r / s)) / r)) + ((exp((-r / (s * single(3.0)))) / r) * ((single(-0.125) / s) / -single(pi))); end
\begin{array}{l}
\\
\frac{0.25}{s \cdot \left(2 \cdot \pi\right)} \cdot \frac{e^{\frac{-r}{s}}}{r} + \frac{e^{\frac{-r}{s \cdot 3}}}{r} \cdot \frac{\frac{-0.125}{s}}{-\pi}
\end{array}
Initial program 99.5%
times-frac99.5%
fma-def99.6%
associate-*l*99.6%
associate-/r*99.6%
metadata-eval99.6%
metadata-eval99.6%
associate-/r*99.5%
associate-*l*99.5%
/-rgt-identity99.5%
fma-def99.5%
Simplified99.5%
*-commutative99.5%
add-sqr-sqrt99.5%
pow299.5%
*-commutative99.5%
Applied egg-rr99.5%
pow199.5%
*-commutative99.5%
unpow299.5%
add-sqr-sqrt99.5%
*-commutative99.5%
associate-*l*99.6%
Applied egg-rr99.6%
pow199.6%
clear-num99.5%
associate-*r*99.5%
*-commutative99.5%
associate-/l*99.5%
metadata-eval99.5%
clear-num99.5%
associate-/l/99.5%
un-div-inv99.5%
add-sqr-sqrt99.5%
pow299.5%
un-div-inv99.5%
Applied egg-rr99.5%
unpow299.5%
add-sqr-sqrt99.5%
frac-2neg99.5%
distribute-neg-frac99.5%
metadata-eval99.5%
Applied egg-rr99.5%
Final simplification99.5%
(FPCore (s r) :precision binary32 (+ (* (/ 0.25 (* s (* 2.0 PI))) (/ (exp (/ (- r) s)) r)) (* (/ (exp (/ (- r) (* s 3.0))) r) (/ (/ 0.125 PI) s))))
float code(float s, float r) {
return ((0.25f / (s * (2.0f * ((float) M_PI)))) * (expf((-r / s)) / r)) + ((expf((-r / (s * 3.0f))) / r) * ((0.125f / ((float) M_PI)) / s));
}
function code(s, r) return Float32(Float32(Float32(Float32(0.25) / Float32(s * Float32(Float32(2.0) * Float32(pi)))) * Float32(exp(Float32(Float32(-r) / s)) / r)) + Float32(Float32(exp(Float32(Float32(-r) / Float32(s * Float32(3.0)))) / r) * Float32(Float32(Float32(0.125) / Float32(pi)) / s))) end
function tmp = code(s, r) tmp = ((single(0.25) / (s * (single(2.0) * single(pi)))) * (exp((-r / s)) / r)) + ((exp((-r / (s * single(3.0)))) / r) * ((single(0.125) / single(pi)) / s)); end
\begin{array}{l}
\\
\frac{0.25}{s \cdot \left(2 \cdot \pi\right)} \cdot \frac{e^{\frac{-r}{s}}}{r} + \frac{e^{\frac{-r}{s \cdot 3}}}{r} \cdot \frac{\frac{0.125}{\pi}}{s}
\end{array}
Initial program 99.5%
times-frac99.5%
fma-def99.6%
associate-*l*99.6%
associate-/r*99.6%
metadata-eval99.6%
metadata-eval99.6%
associate-/r*99.5%
associate-*l*99.5%
/-rgt-identity99.5%
fma-def99.5%
Simplified99.5%
*-commutative99.5%
add-sqr-sqrt99.5%
pow299.5%
*-commutative99.5%
Applied egg-rr99.5%
pow199.5%
*-commutative99.5%
unpow299.5%
add-sqr-sqrt99.5%
*-commutative99.5%
associate-*l*99.6%
Applied egg-rr99.6%
pow199.6%
clear-num99.5%
associate-*r*99.5%
*-commutative99.5%
associate-/l*99.5%
metadata-eval99.5%
clear-num99.5%
associate-/l/99.5%
un-div-inv99.5%
add-sqr-sqrt99.5%
pow299.5%
un-div-inv99.5%
Applied egg-rr99.5%
unpow299.5%
add-sqr-sqrt99.5%
associate-/l/99.5%
associate-/r*99.5%
Applied egg-rr99.5%
Final simplification99.5%
(FPCore (s r) :precision binary32 (+ (/ 0.125 (* s (* PI r))) (* (/ (exp (/ (- r) (* s 3.0))) r) (/ 0.75 (* 6.0 (* s PI))))))
float code(float s, float r) {
return (0.125f / (s * (((float) M_PI) * r))) + ((expf((-r / (s * 3.0f))) / r) * (0.75f / (6.0f * (s * ((float) M_PI)))));
}
function code(s, r) return Float32(Float32(Float32(0.125) / Float32(s * Float32(Float32(pi) * r))) + Float32(Float32(exp(Float32(Float32(-r) / Float32(s * Float32(3.0)))) / r) * Float32(Float32(0.75) / Float32(Float32(6.0) * Float32(s * Float32(pi)))))) end
function tmp = code(s, r) tmp = (single(0.125) / (s * (single(pi) * r))) + ((exp((-r / (s * single(3.0)))) / r) * (single(0.75) / (single(6.0) * (s * single(pi))))); end
\begin{array}{l}
\\
\frac{0.125}{s \cdot \left(\pi \cdot r\right)} + \frac{e^{\frac{-r}{s \cdot 3}}}{r} \cdot \frac{0.75}{6 \cdot \left(s \cdot \pi\right)}
\end{array}
Initial program 99.5%
times-frac99.5%
fma-def99.6%
associate-*l*99.6%
associate-/r*99.6%
metadata-eval99.6%
metadata-eval99.6%
associate-/r*99.5%
associate-*l*99.5%
/-rgt-identity99.5%
fma-def99.5%
Simplified99.5%
Taylor expanded in r around 0 9.2%
associate-*l/9.2%
*-commutative9.2%
associate-*l*9.2%
add-sqr-sqrt9.2%
unpow29.2%
associate-/r*9.2%
un-div-inv9.2%
unpow29.2%
add-sqr-sqrt9.2%
Applied egg-rr9.2%
Taylor expanded in r around 0 9.2%
*-commutative9.2%
associate-*r*9.2%
Simplified9.2%
Final simplification9.2%
(FPCore (s r) :precision binary32 (+ (/ 0.125 (* r (* s PI))) (* (/ 0.75 (* 6.0 (* s PI))) (/ (exp (* (/ r s) -0.3333333333333333)) r))))
float code(float s, float r) {
return (0.125f / (r * (s * ((float) M_PI)))) + ((0.75f / (6.0f * (s * ((float) M_PI)))) * (expf(((r / s) * -0.3333333333333333f)) / r));
}
function code(s, r) return Float32(Float32(Float32(0.125) / Float32(r * Float32(s * Float32(pi)))) + Float32(Float32(Float32(0.75) / Float32(Float32(6.0) * Float32(s * Float32(pi)))) * Float32(exp(Float32(Float32(r / s) * Float32(-0.3333333333333333))) / r))) end
function tmp = code(s, r) tmp = (single(0.125) / (r * (s * single(pi)))) + ((single(0.75) / (single(6.0) * (s * single(pi)))) * (exp(((r / s) * single(-0.3333333333333333))) / r)); end
\begin{array}{l}
\\
\frac{0.125}{r \cdot \left(s \cdot \pi\right)} + \frac{0.75}{6 \cdot \left(s \cdot \pi\right)} \cdot \frac{e^{\frac{r}{s} \cdot -0.3333333333333333}}{r}
\end{array}
Initial program 99.5%
times-frac99.5%
fma-def99.6%
associate-*l*99.6%
associate-/r*99.6%
metadata-eval99.6%
metadata-eval99.6%
associate-/r*99.5%
associate-*l*99.5%
/-rgt-identity99.5%
fma-def99.5%
Simplified99.5%
Taylor expanded in r around 0 9.2%
Taylor expanded in s around 0 9.2%
neg-mul-19.2%
*-commutative9.2%
times-frac9.2%
metadata-eval9.2%
*-commutative9.2%
Applied egg-rr9.2%
Final simplification9.2%
herbie shell --seed 2024027
(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))))