
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log (- 1.0 u1)))) (cos (* (* 2.0 PI) u2))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-logf((1.0f - u1))) * cosf(((2.0f * ((float) M_PI)) * u2));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log(Float32(Float32(1.0) - u1)))) * cos(Float32(Float32(Float32(2.0) * Float32(pi)) * u2))) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(-log((single(1.0) - u1))) * cos(((single(2.0) * single(pi)) * u2)); end
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \cos \left(\left(2 \cdot \pi\right) \cdot u2\right)
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 6 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log (- 1.0 u1)))) (cos (* (* 2.0 PI) u2))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-logf((1.0f - u1))) * cosf(((2.0f * ((float) M_PI)) * u2));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log(Float32(Float32(1.0) - u1)))) * cos(Float32(Float32(Float32(2.0) * Float32(pi)) * u2))) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(-log((single(1.0) - u1))) * cos(((single(2.0) * single(pi)) * u2)); end
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \cos \left(\left(2 \cdot \pi\right) \cdot u2\right)
\end{array}
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (sin (* PI u2))))
(*
(sqrt (- (log1p (- u1))))
(+ (cos (* 2.0 (* PI u2))) (fma (- t_0) t_0 (pow t_0 2.0))))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = sinf((((float) M_PI) * u2));
return sqrtf(-log1pf(-u1)) * (cosf((2.0f * (((float) M_PI) * u2))) + fmaf(-t_0, t_0, powf(t_0, 2.0f)));
}
function code(cosTheta_i, u1, u2) t_0 = sin(Float32(Float32(pi) * u2)) return Float32(sqrt(Float32(-log1p(Float32(-u1)))) * Float32(cos(Float32(Float32(2.0) * Float32(Float32(pi) * u2))) + fma(Float32(-t_0), t_0, (t_0 ^ Float32(2.0))))) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin \left(\pi \cdot u2\right)\\
\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \left(\cos \left(2 \cdot \left(\pi \cdot u2\right)\right) + \mathsf{fma}\left(-t_0, t_0, {t_0}^{2}\right)\right)
\end{array}
\end{array}
Initial program 60.8%
sub-neg60.8%
log1p-def99.1%
associate-*l*99.1%
Simplified99.1%
cos-298.9%
prod-diff98.9%
fma-neg98.9%
cos-299.1%
pow299.1%
Applied egg-rr99.1%
Final simplification99.1%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (cos (* u2 (* 2.0 PI)))))
(if (<= t_0 0.9999300241470337)
(* t_0 (sqrt u1))
(sqrt (- (log1p (- u1)))))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = cosf((u2 * (2.0f * ((float) M_PI))));
float tmp;
if (t_0 <= 0.9999300241470337f) {
tmp = t_0 * sqrtf(u1);
} else {
tmp = sqrtf(-log1pf(-u1));
}
return tmp;
}
function code(cosTheta_i, u1, u2) t_0 = cos(Float32(u2 * Float32(Float32(2.0) * Float32(pi)))) tmp = Float32(0.0) if (t_0 <= Float32(0.9999300241470337)) tmp = Float32(t_0 * sqrt(u1)); else tmp = sqrt(Float32(-log1p(Float32(-u1)))); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \cos \left(u2 \cdot \left(2 \cdot \pi\right)\right)\\
\mathbf{if}\;t_0 \leq 0.9999300241470337:\\
\;\;\;\;t_0 \cdot \sqrt{u1}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-\mathsf{log1p}\left(-u1\right)}\\
\end{array}
\end{array}
if (cos.f32 (*.f32 (*.f32 2 (PI.f32)) u2)) < 0.999930024Initial program 58.8%
sub-neg58.8%
log1p-udef98.1%
add-cbrt-cube98.1%
pow1/394.9%
Applied egg-rr72.9%
Taylor expanded in u1 around 0 76.8%
if 0.999930024 < (cos.f32 (*.f32 (*.f32 2 (PI.f32)) u2)) Initial program 61.7%
sub-neg61.7%
log1p-def99.5%
associate-*l*99.5%
Simplified99.5%
Taylor expanded in u2 around 0 96.0%
Final simplification90.2%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log1p (- u1)))) (cos (* 2.0 (* PI u2)))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-log1pf(-u1)) * cosf((2.0f * (((float) M_PI) * u2)));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log1p(Float32(-u1)))) * cos(Float32(Float32(2.0) * Float32(Float32(pi) * u2)))) end
\begin{array}{l}
\\
\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \cos \left(2 \cdot \left(\pi \cdot u2\right)\right)
\end{array}
Initial program 60.8%
sub-neg60.8%
log1p-def99.1%
associate-*l*99.1%
Simplified99.1%
Final simplification99.1%
(FPCore (cosTheta_i u1 u2) :precision binary32 (sqrt (- (log1p (- u1)))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-log1pf(-u1));
}
function code(cosTheta_i, u1, u2) return sqrt(Float32(-log1p(Float32(-u1)))) end
\begin{array}{l}
\\
\sqrt{-\mathsf{log1p}\left(-u1\right)}
\end{array}
Initial program 60.8%
sub-neg60.8%
log1p-def99.1%
associate-*l*99.1%
Simplified99.1%
Taylor expanded in u2 around 0 79.5%
Final simplification79.5%
(FPCore (cosTheta_i u1 u2) :precision binary32 (sqrt (- u1 (* (* u1 u1) -0.5))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf((u1 - ((u1 * u1) * -0.5f)));
}
real(4) function code(costheta_i, u1, u2)
real(4), intent (in) :: costheta_i
real(4), intent (in) :: u1
real(4), intent (in) :: u2
code = sqrt((u1 - ((u1 * u1) * (-0.5e0))))
end function
function code(cosTheta_i, u1, u2) return sqrt(Float32(u1 - Float32(Float32(u1 * u1) * Float32(-0.5)))) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt((u1 - ((u1 * u1) * single(-0.5)))); end
\begin{array}{l}
\\
\sqrt{u1 - \left(u1 \cdot u1\right) \cdot -0.5}
\end{array}
Initial program 60.8%
sub-neg60.8%
log1p-def99.1%
associate-*l*99.1%
Simplified99.1%
Taylor expanded in u2 around 0 79.5%
Taylor expanded in u1 around 0 74.5%
Taylor expanded in u1 around 0 71.2%
unpow271.2%
Simplified71.2%
Taylor expanded in u1 around 0 71.2%
neg-mul-171.2%
+-commutative71.2%
fma-def71.2%
fma-neg71.2%
*-commutative71.2%
unpow271.2%
Simplified71.2%
Final simplification71.2%
(FPCore (cosTheta_i u1 u2) :precision binary32 (sqrt u1))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(u1);
}
real(4) function code(costheta_i, u1, u2)
real(4), intent (in) :: costheta_i
real(4), intent (in) :: u1
real(4), intent (in) :: u2
code = sqrt(u1)
end function
function code(cosTheta_i, u1, u2) return sqrt(u1) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(u1); end
\begin{array}{l}
\\
\sqrt{u1}
\end{array}
Initial program 60.8%
sub-neg60.8%
log1p-def99.1%
associate-*l*99.1%
Simplified99.1%
Taylor expanded in u2 around 0 79.5%
Taylor expanded in u1 around 0 74.5%
expm1-log1p-u74.5%
expm1-udef63.6%
fma-def63.6%
fma-def63.6%
unpow263.6%
Applied egg-rr63.6%
expm1-def74.5%
expm1-log1p74.5%
neg-sub074.5%
metadata-eval74.5%
fma-udef74.5%
neg-mul-174.5%
associate--r+74.5%
metadata-eval74.5%
neg-sub074.5%
remove-double-neg74.5%
Simplified74.5%
Taylor expanded in u1 around 0 63.2%
Final simplification63.2%
herbie shell --seed 2023228
(FPCore (cosTheta_i u1 u2)
:name "Beckmann Sample, near normal, slope_x"
: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)))) (cos (* (* 2.0 PI) u2))))