
(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 4 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 56.5%
sub-neg56.5%
log1p-define98.4%
Simplified98.4%
Final simplification98.4%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (* (* 2.0 PI) u2)))
(if (<= t_0 0.003000000026077032)
(* (sqrt (- (log1p (- u1)))) (* 2.0 (* PI u2)))
(* (sin t_0) (sqrt u1)))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = (2.0f * ((float) M_PI)) * u2;
float tmp;
if (t_0 <= 0.003000000026077032f) {
tmp = sqrtf(-log1pf(-u1)) * (2.0f * (((float) M_PI) * u2));
} else {
tmp = sinf(t_0) * sqrtf(u1);
}
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(0.003000000026077032)) tmp = Float32(sqrt(Float32(-log1p(Float32(-u1)))) * Float32(Float32(2.0) * Float32(Float32(pi) * u2))); else tmp = Float32(sin(t_0) * sqrt(u1)); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(2 \cdot \pi\right) \cdot u2\\
\mathbf{if}\;t\_0 \leq 0.003000000026077032:\\
\;\;\;\;\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \left(2 \cdot \left(\pi \cdot u2\right)\right)\\
\mathbf{else}:\\
\;\;\;\;\sin t\_0 \cdot \sqrt{u1}\\
\end{array}
\end{array}
if (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2) < 0.00300000003Initial program 57.6%
sub-neg57.6%
log1p-define98.5%
Simplified98.5%
add-sqr-sqrt97.7%
pow297.7%
associate-*l*97.7%
Applied egg-rr97.7%
unpow297.7%
add-sqr-sqrt98.5%
*-commutative98.5%
associate-*r*98.5%
*-commutative98.5%
+-lft-identity98.5%
sin-098.5%
+-commutative98.5%
*-un-lft-identity98.5%
metadata-eval98.5%
associate-*r*98.5%
metadata-eval98.5%
associate-/r/98.5%
un-div-inv98.5%
+-commutative98.5%
sin-098.5%
+-lft-identity98.5%
*-commutative98.5%
associate-*r*98.5%
*-commutative98.5%
Applied egg-rr98.5%
Taylor expanded in u2 around 0 97.9%
if 0.00300000003 < (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2) Initial program 54.3%
sub-neg54.3%
log1p-define98.2%
Simplified98.2%
expm1-log1p-u98.2%
expm1-undefine69.0%
Applied egg-rr54.9%
Taylor expanded in u1 around 0 77.2%
associate-*r*77.2%
*-commutative77.2%
associate-*r*77.2%
*-commutative77.2%
Simplified77.2%
Final simplification91.0%
(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(Float32(2.0) * 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(\left(2 \cdot \pi\right) \cdot u2\right) \cdot \sqrt{u1}
\end{array}
Initial program 56.5%
sub-neg56.5%
log1p-define98.4%
Simplified98.4%
expm1-log1p-u98.4%
expm1-undefine37.2%
Applied egg-rr31.3%
Taylor expanded in u1 around 0 77.5%
associate-*r*77.5%
*-commutative77.5%
associate-*r*77.5%
*-commutative77.5%
Simplified77.5%
Final simplification77.5%
(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(Float32(pi) * 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(\left(\pi \cdot u2\right) \cdot \sqrt{u1}\right)
\end{array}
Initial program 56.5%
sub-neg56.5%
log1p-define98.4%
Simplified98.4%
Taylor expanded in u1 around 0 -0.0%
associate-*r*-0.0%
unpow2-0.0%
rem-square-sqrt4.0%
*-commutative4.0%
associate-*l*4.0%
*-commutative4.0%
mul-1-neg4.0%
Simplified4.0%
*-commutative4.0%
add-sqr-sqrt-0.0%
sqrt-unprod77.5%
sqr-neg77.5%
add-sqr-sqrt77.5%
add-exp-log73.0%
*-commutative73.0%
associate-*r*73.0%
*-commutative73.0%
Applied egg-rr73.0%
Taylor expanded in u2 around 0 67.6%
Final simplification67.6%
herbie shell --seed 2024115
(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))))