
(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 5 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 (* (cos (* (* 2.0 PI) u2)) (sqrt (- (log1p (- u1))))))
float code(float cosTheta_i, float u1, float u2) {
return cosf(((2.0f * ((float) M_PI)) * u2)) * sqrtf(-log1pf(-u1));
}
function code(cosTheta_i, u1, u2) return Float32(cos(Float32(Float32(Float32(2.0) * Float32(pi)) * u2)) * sqrt(Float32(-log1p(Float32(-u1))))) end
\begin{array}{l}
\\
\cos \left(\left(2 \cdot \pi\right) \cdot u2\right) \cdot \sqrt{-\mathsf{log1p}\left(-u1\right)}
\end{array}
Initial program 58.7%
sub-neg58.7%
log1p-def99.2%
Simplified99.2%
Final simplification99.2%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (cos (* (* 2.0 PI) u2))))
(if (<= t_0 0.9999998211860657)
(* t_0 (sqrt (* u1 (- (- -1.0) (* u1 -0.5)))))
(sqrt (- (log1p (- u1)))))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = cosf(((2.0f * ((float) M_PI)) * u2));
float tmp;
if (t_0 <= 0.9999998211860657f) {
tmp = t_0 * sqrtf((u1 * (-(-1.0f) - (u1 * -0.5f))));
} else {
tmp = sqrtf(-log1pf(-u1));
}
return tmp;
}
function code(cosTheta_i, u1, u2) t_0 = cos(Float32(Float32(Float32(2.0) * Float32(pi)) * u2)) tmp = Float32(0.0) if (t_0 <= Float32(0.9999998211860657)) tmp = Float32(t_0 * sqrt(Float32(u1 * Float32(Float32(-Float32(-1.0)) - Float32(u1 * Float32(-0.5)))))); else tmp = sqrt(Float32(-log1p(Float32(-u1)))); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \cos \left(\left(2 \cdot \pi\right) \cdot u2\right)\\
\mathbf{if}\;t_0 \leq 0.9999998211860657:\\
\;\;\;\;t_0 \cdot \sqrt{u1 \cdot \left(\left(--1\right) - u1 \cdot -0.5\right)}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-\mathsf{log1p}\left(-u1\right)}\\
\end{array}
\end{array}
if (cos.f32 (*.f32 (*.f32 2 (PI.f32)) u2)) < 0.999999821Initial program 55.8%
Taylor expanded in u1 around 0 89.7%
*-commutative89.7%
*-commutative89.7%
unpow289.7%
associate-*l*89.7%
distribute-lft-out89.8%
Simplified89.8%
if 0.999999821 < (cos.f32 (*.f32 (*.f32 2 (PI.f32)) u2)) Initial program 60.6%
sub-neg60.6%
log1p-def99.6%
Simplified99.6%
Taylor expanded in u2 around 0 99.5%
Final simplification95.8%
(FPCore (cosTheta_i u1 u2) :precision binary32 (if (<= (cos (* (* 2.0 PI) u2)) 0.9999960064888) (* (cos (* PI (* 2.0 u2))) (sqrt u1)) (sqrt (- (log1p (- u1))))))
float code(float cosTheta_i, float u1, float u2) {
float tmp;
if (cosf(((2.0f * ((float) M_PI)) * u2)) <= 0.9999960064888f) {
tmp = cosf((((float) M_PI) * (2.0f * u2))) * sqrtf(u1);
} else {
tmp = sqrtf(-log1pf(-u1));
}
return tmp;
}
function code(cosTheta_i, u1, u2) tmp = Float32(0.0) if (cos(Float32(Float32(Float32(2.0) * Float32(pi)) * u2)) <= Float32(0.9999960064888)) tmp = Float32(cos(Float32(Float32(pi) * Float32(Float32(2.0) * u2))) * sqrt(u1)); else tmp = sqrt(Float32(-log1p(Float32(-u1)))); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\cos \left(\left(2 \cdot \pi\right) \cdot u2\right) \leq 0.9999960064888:\\
\;\;\;\;\cos \left(\pi \cdot \left(2 \cdot u2\right)\right) \cdot \sqrt{u1}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-\mathsf{log1p}\left(-u1\right)}\\
\end{array}
\end{array}
if (cos.f32 (*.f32 (*.f32 2 (PI.f32)) u2)) < 0.999996006Initial program 56.6%
sub-neg56.6%
log1p-def98.4%
Simplified98.4%
log1p-expm1-u98.2%
associate-*l*98.2%
Applied egg-rr98.2%
Applied egg-rr76.1%
Taylor expanded in u1 around 0 78.4%
pow-base-178.4%
*-lft-identity78.4%
*-commutative78.4%
associate-*r*78.4%
*-commutative78.4%
Simplified78.4%
if 0.999996006 < (cos.f32 (*.f32 (*.f32 2 (PI.f32)) u2)) Initial program 59.7%
sub-neg59.7%
log1p-def99.6%
Simplified99.6%
Taylor expanded in u2 around 0 98.6%
Final simplification92.0%
(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 58.7%
sub-neg58.7%
log1p-def99.2%
Simplified99.2%
Taylor expanded in u2 around 0 82.2%
Final simplification82.2%
(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 58.7%
sub-neg58.7%
log1p-def99.2%
Simplified99.2%
Taylor expanded in u2 around 0 82.2%
add-sqr-sqrt81.5%
pow281.5%
pow1/281.5%
sqrt-pow181.5%
add-sqr-sqrt81.5%
sqrt-unprod81.5%
sqr-neg81.5%
sqrt-unprod-0.0%
add-sqr-sqrt-0.0%
add-sqr-sqrt-0.0%
sqrt-unprod64.0%
sqr-neg64.0%
sqrt-unprod64.0%
add-sqr-sqrt64.0%
metadata-eval64.0%
Applied egg-rr64.0%
Taylor expanded in u1 around 0 65.8%
Final simplification65.8%
herbie shell --seed 2023319
(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))))