
(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 (* (sqrt (- (log1p (- u1)))) (cos (pow E (log (* u2 (* 2.0 PI)))))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-log1pf(-u1)) * cosf(powf(((float) M_E), logf((u2 * (2.0f * ((float) M_PI))))));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log1p(Float32(-u1)))) * cos((Float32(exp(1)) ^ log(Float32(u2 * Float32(Float32(2.0) * Float32(pi))))))) end
\begin{array}{l}
\\
\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \cos \left({e}^{\log \left(u2 \cdot \left(2 \cdot \pi\right)\right)}\right)
\end{array}
Initial program 58.0%
sub-neg58.0%
log1p-def99.0%
Simplified99.0%
add-exp-log99.0%
associate-*l*99.0%
Applied egg-rr99.0%
*-un-lft-identity99.0%
exp-prod99.1%
*-commutative99.1%
associate-*l*99.1%
Applied egg-rr99.1%
exp-1-e99.1%
*-commutative99.1%
associate-*r*99.1%
Simplified99.1%
Final simplification99.1%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (cos (* u2 (* 2.0 PI)))))
(if (<= t_0 0.9999974966049194)
(* 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((u2 * (2.0f * ((float) M_PI))));
float tmp;
if (t_0 <= 0.9999974966049194f) {
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(u2 * Float32(Float32(2.0) * Float32(pi)))) tmp = Float32(0.0) if (t_0 <= Float32(0.9999974966049194)) tmp = Float32(t_0 * sqrt(Float32(Float32(-u1) * 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(u2 \cdot \left(2 \cdot \pi\right)\right)\\
\mathbf{if}\;t_0 \leq 0.9999974966049194:\\
\;\;\;\;t_0 \cdot \sqrt{\left(-u1\right) \cdot \left(-1 + 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)) < 0.999997497Initial program 55.8%
Taylor expanded in u1 around 0 87.1%
*-commutative87.1%
*-commutative87.1%
unpow287.1%
associate-*l*87.1%
distribute-lft-out87.1%
Simplified87.1%
if 0.999997497 < (cos.f32 (*.f32 (*.f32 2 (PI.f32)) u2)) Initial program 59.6%
sub-neg59.6%
log1p-def99.7%
Simplified99.7%
Taylor expanded in u2 around 0 98.5%
Final simplification93.8%
(FPCore (cosTheta_i u1 u2) :precision binary32 (if (<= (cos (* u2 (* 2.0 PI))) 0.9999849796295166) (* (sqrt u1) (cos (* 2.0 (* u2 PI)))) (sqrt (- (log1p (- u1))))))
float code(float cosTheta_i, float u1, float u2) {
float tmp;
if (cosf((u2 * (2.0f * ((float) M_PI)))) <= 0.9999849796295166f) {
tmp = sqrtf(u1) * cosf((2.0f * (u2 * ((float) M_PI))));
} else {
tmp = sqrtf(-log1pf(-u1));
}
return tmp;
}
function code(cosTheta_i, u1, u2) tmp = Float32(0.0) if (cos(Float32(u2 * Float32(Float32(2.0) * Float32(pi)))) <= Float32(0.9999849796295166)) tmp = Float32(sqrt(u1) * cos(Float32(Float32(2.0) * Float32(u2 * Float32(pi))))); else tmp = sqrt(Float32(-log1p(Float32(-u1)))); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\cos \left(u2 \cdot \left(2 \cdot \pi\right)\right) \leq 0.9999849796295166:\\
\;\;\;\;\sqrt{u1} \cdot \cos \left(2 \cdot \left(u2 \cdot \pi\right)\right)\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-\mathsf{log1p}\left(-u1\right)}\\
\end{array}
\end{array}
if (cos.f32 (*.f32 (*.f32 2 (PI.f32)) u2)) < 0.99998498Initial program 55.9%
sub-neg55.9%
log1p-def97.9%
Simplified97.9%
add-sqr-sqrt84.1%
pow284.1%
associate-*l*84.1%
Applied egg-rr84.1%
Taylor expanded in u1 around 0 64.8%
mul-1-neg64.8%
Simplified64.8%
Taylor expanded in u2 around inf 76.0%
if 0.99998498 < (cos.f32 (*.f32 (*.f32 2 (PI.f32)) u2)) Initial program 59.2%
sub-neg59.2%
log1p-def99.7%
Simplified99.7%
Taylor expanded in u2 around 0 97.1%
Final simplification89.5%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log1p (- u1)))) (cos (* u2 (* 2.0 PI)))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-log1pf(-u1)) * cosf((u2 * (2.0f * ((float) M_PI))));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log1p(Float32(-u1)))) * cos(Float32(u2 * Float32(Float32(2.0) * Float32(pi))))) end
\begin{array}{l}
\\
\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \cos \left(u2 \cdot \left(2 \cdot \pi\right)\right)
\end{array}
Initial program 58.0%
sub-neg58.0%
log1p-def99.0%
Simplified99.0%
Final simplification99.0%
(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 58.0%
sub-neg58.0%
log1p-def99.0%
Simplified99.0%
Taylor expanded in u2 around 0 76.7%
Final simplification76.7%
(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 58.0%
add-sqr-sqrt55.1%
sqrt-unprod55.4%
swap-sqr55.3%
Applied egg-rr69.4%
Taylor expanded in u2 around 0 35.2%
log1p-def59.9%
Simplified59.9%
Taylor expanded in u1 around 0 61.5%
Final simplification61.5%
herbie shell --seed 2024021
(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))))