
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log (- 1.0 u1)))) (sin (* (* 2.0 PI) u2))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-logf((1.0f - u1))) * sinf(((2.0f * ((float) M_PI)) * u2));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log(Float32(Float32(1.0) - u1)))) * sin(Float32(Float32(Float32(2.0) * Float32(pi)) * u2))) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(-log((single(1.0) - u1))) * sin(((single(2.0) * single(pi)) * u2)); end
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \sin \left(\left(2 \cdot \pi\right) \cdot u2\right)
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 5 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log (- 1.0 u1)))) (sin (* (* 2.0 PI) u2))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-logf((1.0f - u1))) * sinf(((2.0f * ((float) M_PI)) * u2));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log(Float32(Float32(1.0) - u1)))) * sin(Float32(Float32(Float32(2.0) * Float32(pi)) * u2))) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(-log((single(1.0) - u1))) * sin(((single(2.0) * single(pi)) * u2)); end
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \sin \left(\left(2 \cdot \pi\right) \cdot u2\right)
\end{array}
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log1p (- u1)))) (sin (* 2.0 (* PI u2)))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-log1pf(-u1)) * sinf((2.0f * (((float) M_PI) * u2)));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log1p(Float32(-u1)))) * sin(Float32(Float32(2.0) * Float32(Float32(pi) * u2)))) end
\begin{array}{l}
\\
\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \sin \left(2 \cdot \left(\pi \cdot u2\right)\right)
\end{array}
Initial program 53.4%
sub-neg53.4%
log1p-def98.6%
associate-*l*98.6%
Simplified98.6%
Final simplification98.6%
(FPCore (cosTheta_i u1 u2) :precision binary32 (if (<= (* u2 (* 2.0 PI)) 0.013000000268220901) (* (sqrt (- (log1p (- u1)))) (* PI (* 2.0 u2))) (* (sin (* 2.0 (* PI u2))) (sqrt u1))))
float code(float cosTheta_i, float u1, float u2) {
float tmp;
if ((u2 * (2.0f * ((float) M_PI))) <= 0.013000000268220901f) {
tmp = sqrtf(-log1pf(-u1)) * (((float) M_PI) * (2.0f * u2));
} else {
tmp = sinf((2.0f * (((float) M_PI) * u2))) * sqrtf(u1);
}
return tmp;
}
function code(cosTheta_i, u1, u2) tmp = Float32(0.0) if (Float32(u2 * Float32(Float32(2.0) * Float32(pi))) <= Float32(0.013000000268220901)) tmp = Float32(sqrt(Float32(-log1p(Float32(-u1)))) * Float32(Float32(pi) * Float32(Float32(2.0) * u2))); else tmp = Float32(sin(Float32(Float32(2.0) * Float32(Float32(pi) * u2))) * sqrt(u1)); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;u2 \cdot \left(2 \cdot \pi\right) \leq 0.013000000268220901:\\
\;\;\;\;\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \left(\pi \cdot \left(2 \cdot u2\right)\right)\\
\mathbf{else}:\\
\;\;\;\;\sin \left(2 \cdot \left(\pi \cdot u2\right)\right) \cdot \sqrt{u1}\\
\end{array}
\end{array}
if (*.f32 (*.f32 2 (PI.f32)) u2) < 0.0130000003Initial program 54.9%
sub-neg54.9%
log1p-def98.6%
associate-*l*98.6%
Simplified98.6%
add-cbrt-cube98.6%
add-cbrt-cube98.6%
cbrt-unprod98.5%
pow398.5%
pow398.5%
Applied egg-rr98.5%
Taylor expanded in u2 around 0 96.2%
associate-*r*96.2%
*-commutative96.2%
Simplified96.2%
if 0.0130000003 < (*.f32 (*.f32 2 (PI.f32)) u2) Initial program 50.3%
sub-neg50.3%
log1p-def98.5%
associate-*l*98.5%
Simplified98.5%
neg-mul-198.5%
log1p-udef50.3%
sub-neg50.3%
neg-mul-150.3%
add-sqr-sqrt50.4%
pow250.4%
Applied egg-rr78.4%
Taylor expanded in u1 around 0 80.5%
Final simplification91.3%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sin (* 2.0 (* PI u2))) (sqrt u1)))
float code(float cosTheta_i, float u1, float u2) {
return sinf((2.0f * (((float) M_PI) * u2))) * sqrtf(u1);
}
function code(cosTheta_i, u1, u2) return Float32(sin(Float32(Float32(2.0) * Float32(Float32(pi) * u2))) * sqrt(u1)) end
function tmp = code(cosTheta_i, u1, u2) tmp = sin((single(2.0) * (single(pi) * u2))) * sqrt(u1); end
\begin{array}{l}
\\
\sin \left(2 \cdot \left(\pi \cdot u2\right)\right) \cdot \sqrt{u1}
\end{array}
Initial program 53.4%
sub-neg53.4%
log1p-def98.6%
associate-*l*98.6%
Simplified98.6%
neg-mul-198.6%
log1p-udef53.4%
sub-neg53.4%
neg-mul-153.4%
add-sqr-sqrt53.4%
pow253.4%
Applied egg-rr77.0%
Taylor expanded in u1 around 0 79.1%
Final simplification79.1%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (* PI (* 2.0 u2)) (sqrt u1)))
float code(float cosTheta_i, float u1, float u2) {
return (((float) M_PI) * (2.0f * u2)) * sqrtf(u1);
}
function code(cosTheta_i, u1, u2) return Float32(Float32(Float32(pi) * Float32(Float32(2.0) * u2)) * sqrt(u1)) end
function tmp = code(cosTheta_i, u1, u2) tmp = (single(pi) * (single(2.0) * u2)) * sqrt(u1); end
\begin{array}{l}
\\
\left(\pi \cdot \left(2 \cdot u2\right)\right) \cdot \sqrt{u1}
\end{array}
Initial program 53.4%
Taylor expanded in u1 around 0 79.1%
mul-1-neg79.1%
Simplified79.1%
Taylor expanded in u2 around 0 67.5%
associate-*r*67.5%
associate-*r*67.5%
*-commutative67.5%
Simplified67.5%
Final simplification67.5%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* PI (* (* 2.0 u2) (sqrt u1))))
float code(float cosTheta_i, float u1, float u2) {
return ((float) M_PI) * ((2.0f * u2) * sqrtf(u1));
}
function code(cosTheta_i, u1, u2) return Float32(Float32(pi) * Float32(Float32(Float32(2.0) * u2) * sqrt(u1))) end
function tmp = code(cosTheta_i, u1, u2) tmp = single(pi) * ((single(2.0) * u2) * sqrt(u1)); end
\begin{array}{l}
\\
\pi \cdot \left(\left(2 \cdot u2\right) \cdot \sqrt{u1}\right)
\end{array}
Initial program 53.4%
Taylor expanded in u1 around 0 79.1%
mul-1-neg79.1%
Simplified79.1%
Taylor expanded in u2 around 0 67.5%
associate-*r*67.5%
associate-*r*67.5%
*-commutative67.5%
Simplified67.5%
add-cube-cbrt67.3%
pow367.3%
Applied egg-rr67.3%
add-log-exp27.4%
rem-cube-cbrt27.4%
associate-*l*27.4%
exp-prod27.4%
Applied egg-rr27.4%
log-pow67.5%
*-commutative67.5%
rem-log-exp67.5%
Simplified67.5%
Final simplification67.5%
herbie shell --seed 2023240
(FPCore (cosTheta_i u1 u2)
:name "Beckmann Sample, near normal, slope_y"
:precision binary32
:pre (and (and (and (> cosTheta_i 0.9999) (<= cosTheta_i 1.0)) (and (<= 2.328306437e-10 u1) (<= u1 1.0))) (and (<= 2.328306437e-10 u2) (<= u2 1.0)))
(* (sqrt (- (log (- 1.0 u1)))) (sin (* (* 2.0 PI) u2))))