
(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(Float32(2.0) * Float32(pi)) * u2))) end
\begin{array}{l}
\\
\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \sin \left(\left(2 \cdot \pi\right) \cdot u2\right)
\end{array}
Initial program 54.0%
sub-neg54.0%
log1p-define98.4%
Simplified98.4%
Final simplification98.4%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (* 2.0 (* PI u2))))
(if (<= (* (* 2.0 PI) u2) 0.010999999940395355)
(* (sqrt (- (log1p (- u1)))) t_0)
(* (sqrt u1) (sin t_0)))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = 2.0f * (((float) M_PI) * u2);
float tmp;
if (((2.0f * ((float) M_PI)) * u2) <= 0.010999999940395355f) {
tmp = sqrtf(-log1pf(-u1)) * t_0;
} else {
tmp = sqrtf(u1) * sinf(t_0);
}
return tmp;
}
function code(cosTheta_i, u1, u2) t_0 = Float32(Float32(2.0) * Float32(Float32(pi) * u2)) tmp = Float32(0.0) if (Float32(Float32(Float32(2.0) * Float32(pi)) * u2) <= Float32(0.010999999940395355)) tmp = Float32(sqrt(Float32(-log1p(Float32(-u1)))) * t_0); else tmp = Float32(sqrt(u1) * sin(t_0)); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := 2 \cdot \left(\pi \cdot u2\right)\\
\mathbf{if}\;\left(2 \cdot \pi\right) \cdot u2 \leq 0.010999999940395355:\\
\;\;\;\;\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot t\_0\\
\mathbf{else}:\\
\;\;\;\;\sqrt{u1} \cdot \sin t\_0\\
\end{array}
\end{array}
if (*.f32 (*.f32 2 (PI.f32)) u2) < 0.0109999999Initial program 52.5%
sub-neg52.5%
log1p-define98.6%
Simplified98.6%
add-exp-log94.4%
associate-*l*94.4%
Applied egg-rr94.4%
Taylor expanded in u2 around 0 96.6%
if 0.0109999999 < (*.f32 (*.f32 2 (PI.f32)) u2) Initial program 57.6%
Taylor expanded in u1 around 0 75.7%
mul-1-neg75.7%
Simplified75.7%
Taylor expanded in u2 around inf 75.7%
Final simplification90.2%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt u1) (sin (* 2.0 (* PI u2)))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(u1) * sinf((2.0f * (((float) M_PI) * u2)));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(u1) * sin(Float32(Float32(2.0) * Float32(Float32(pi) * u2)))) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(u1) * sin((single(2.0) * (single(pi) * u2))); end
\begin{array}{l}
\\
\sqrt{u1} \cdot \sin \left(2 \cdot \left(\pi \cdot u2\right)\right)
\end{array}
Initial program 54.0%
Taylor expanded in u1 around 0 78.0%
mul-1-neg78.0%
Simplified78.0%
Taylor expanded in u2 around inf 78.0%
Final simplification78.0%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* 2.0 (* PI (* u2 (sqrt u1)))))
float code(float cosTheta_i, float u1, float u2) {
return 2.0f * (((float) M_PI) * (u2 * sqrtf(u1)));
}
function code(cosTheta_i, u1, u2) return Float32(Float32(2.0) * Float32(Float32(pi) * Float32(u2 * sqrt(u1)))) end
function tmp = code(cosTheta_i, u1, u2) tmp = single(2.0) * (single(pi) * (u2 * sqrt(u1))); end
\begin{array}{l}
\\
2 \cdot \left(\pi \cdot \left(u2 \cdot \sqrt{u1}\right)\right)
\end{array}
Initial program 54.0%
Taylor expanded in u1 around 0 78.0%
mul-1-neg78.0%
Simplified78.0%
Taylor expanded in u2 around 0 66.9%
Simplified66.9%
Taylor expanded in u2 around 0 66.9%
associate-*r*66.9%
Simplified66.9%
Final simplification66.9%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* u2 (* PI (sqrt (* u1 4.0)))))
float code(float cosTheta_i, float u1, float u2) {
return u2 * (((float) M_PI) * sqrtf((u1 * 4.0f)));
}
function code(cosTheta_i, u1, u2) return Float32(u2 * Float32(Float32(pi) * sqrt(Float32(u1 * Float32(4.0))))) end
function tmp = code(cosTheta_i, u1, u2) tmp = u2 * (single(pi) * sqrt((u1 * single(4.0)))); end
\begin{array}{l}
\\
u2 \cdot \left(\pi \cdot \sqrt{u1 \cdot 4}\right)
\end{array}
Initial program 54.0%
Taylor expanded in u1 around 0 78.0%
mul-1-neg78.0%
Simplified78.0%
Taylor expanded in u2 around 0 66.9%
Simplified66.9%
add-cube-cbrt66.6%
pow366.6%
Applied egg-rr66.6%
pow166.6%
*-commutative66.6%
rem-cube-cbrt66.9%
associate-*l*66.9%
add-sqr-sqrt66.8%
sqrt-unprod66.9%
*-commutative66.9%
*-commutative66.9%
swap-sqr66.9%
add-sqr-sqrt66.9%
metadata-eval66.9%
Applied egg-rr66.9%
unpow166.9%
Simplified66.9%
Final simplification66.9%
herbie shell --seed 2024039
(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))))