
(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 55.4%
sub-neg55.4%
log1p-def98.4%
Simplified98.4%
Final simplification98.4%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (* (* 2.0 PI) u2)))
(if (<= t_0 0.0024999999441206455)
(* (sqrt (- (log1p (- u1)))) (* PI (* 2.0 u2)))
(* (sin t_0) (sqrt (* u1 (- (* u1 (- -0.5)) -1.0)))))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = (2.0f * ((float) M_PI)) * u2;
float tmp;
if (t_0 <= 0.0024999999441206455f) {
tmp = sqrtf(-log1pf(-u1)) * (((float) M_PI) * (2.0f * u2));
} else {
tmp = sinf(t_0) * sqrtf((u1 * ((u1 * -(-0.5f)) - -1.0f)));
}
return tmp;
}
function code(cosTheta_i, u1, u2) t_0 = Float32(Float32(Float32(2.0) * Float32(pi)) * u2) tmp = Float32(0.0) if (t_0 <= Float32(0.0024999999441206455)) tmp = Float32(sqrt(Float32(-log1p(Float32(-u1)))) * Float32(Float32(pi) * Float32(Float32(2.0) * u2))); else tmp = Float32(sin(t_0) * sqrt(Float32(u1 * Float32(Float32(u1 * Float32(-Float32(-0.5))) - Float32(-1.0))))); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(2 \cdot \pi\right) \cdot u2\\
\mathbf{if}\;t_0 \leq 0.0024999999441206455:\\
\;\;\;\;\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \left(\pi \cdot \left(2 \cdot u2\right)\right)\\
\mathbf{else}:\\
\;\;\;\;\sin t_0 \cdot \sqrt{u1 \cdot \left(u1 \cdot \left(--0.5\right) - -1\right)}\\
\end{array}
\end{array}
if (*.f32 (*.f32 2 (PI.f32)) u2) < 0.00249999994Initial program 55.8%
sub-neg55.8%
log1p-def98.6%
Simplified98.6%
associate-*l*98.6%
sin-298.5%
Applied egg-rr98.5%
associate-*r*98.5%
*-commutative98.5%
*-commutative98.5%
*-commutative98.5%
Simplified98.5%
Taylor expanded in u2 around 0 97.7%
associate-*r*97.7%
*-commutative97.7%
*-commutative97.7%
*-commutative97.7%
Simplified97.7%
if 0.00249999994 < (*.f32 (*.f32 2 (PI.f32)) u2) Initial program 54.7%
Taylor expanded in u1 around 0 87.9%
*-commutative87.9%
*-commutative87.9%
unpow287.9%
associate-*l*87.9%
distribute-lft-out87.9%
Simplified87.9%
Final simplification94.2%
(FPCore (cosTheta_i u1 u2) :precision binary32 (if (<= (* (* 2.0 PI) u2) 0.014999999664723873) (* (sqrt (- (log1p (- u1)))) (* PI (* 2.0 u2))) (* (sqrt u1) (sin (* 2.0 (* PI u2))))))
float code(float cosTheta_i, float u1, float u2) {
float tmp;
if (((2.0f * ((float) M_PI)) * u2) <= 0.014999999664723873f) {
tmp = sqrtf(-log1pf(-u1)) * (((float) M_PI) * (2.0f * u2));
} else {
tmp = sqrtf(u1) * sinf((2.0f * (((float) M_PI) * u2)));
}
return tmp;
}
function code(cosTheta_i, u1, u2) tmp = Float32(0.0) if (Float32(Float32(Float32(2.0) * Float32(pi)) * u2) <= Float32(0.014999999664723873)) tmp = Float32(sqrt(Float32(-log1p(Float32(-u1)))) * Float32(Float32(pi) * Float32(Float32(2.0) * u2))); else tmp = Float32(sqrt(u1) * sin(Float32(Float32(2.0) * Float32(Float32(pi) * u2)))); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\left(2 \cdot \pi\right) \cdot u2 \leq 0.014999999664723873:\\
\;\;\;\;\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \left(\pi \cdot \left(2 \cdot u2\right)\right)\\
\mathbf{else}:\\
\;\;\;\;\sqrt{u1} \cdot \sin \left(2 \cdot \left(\pi \cdot u2\right)\right)\\
\end{array}
\end{array}
if (*.f32 (*.f32 2 (PI.f32)) u2) < 0.0149999997Initial program 55.7%
sub-neg55.7%
log1p-def98.5%
Simplified98.5%
associate-*l*98.5%
sin-298.5%
Applied egg-rr98.5%
associate-*r*98.5%
*-commutative98.5%
*-commutative98.5%
*-commutative98.5%
Simplified98.5%
Taylor expanded in u2 around 0 96.0%
associate-*r*96.0%
*-commutative96.0%
*-commutative96.0%
*-commutative96.0%
Simplified96.0%
if 0.0149999997 < (*.f32 (*.f32 2 (PI.f32)) u2) Initial program 54.6%
Taylor expanded in u1 around 0 77.5%
mul-1-neg77.5%
Simplified77.5%
Taylor expanded in u2 around inf 77.5%
Final simplification90.6%
(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 55.4%
Taylor expanded in u1 around 0 77.6%
mul-1-neg77.6%
Simplified77.6%
Taylor expanded in u2 around inf 77.6%
Final simplification77.6%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* PI (* u2 (sqrt (* u1 4.0)))))
float code(float cosTheta_i, float u1, float u2) {
return ((float) M_PI) * (u2 * sqrtf((u1 * 4.0f)));
}
function code(cosTheta_i, u1, u2) return Float32(Float32(pi) * Float32(u2 * sqrt(Float32(u1 * Float32(4.0))))) end
function tmp = code(cosTheta_i, u1, u2) tmp = single(pi) * (u2 * sqrt((u1 * single(4.0)))); end
\begin{array}{l}
\\
\pi \cdot \left(u2 \cdot \sqrt{u1 \cdot 4}\right)
\end{array}
Initial program 55.4%
Taylor expanded in u1 around 0 77.6%
mul-1-neg77.6%
Simplified77.6%
Taylor expanded in u2 around 0 67.0%
associate-*r*67.0%
*-commutative67.0%
Simplified67.0%
expm1-log1p-u67.0%
expm1-udef26.8%
*-commutative26.8%
associate-*l*26.8%
add-sqr-sqrt26.8%
sqrt-unprod26.8%
*-commutative26.8%
*-commutative26.8%
swap-sqr26.8%
add-sqr-sqrt26.8%
metadata-eval26.8%
Applied egg-rr26.8%
expm1-def67.0%
expm1-log1p67.0%
Simplified67.0%
Final simplification67.0%
herbie shell --seed 2023306
(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))))