
(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 (+ 1.0 (fma u2 (* PI 2.0) -1.0)))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-log1pf(-u1)) * cosf((1.0f + fmaf(u2, (((float) M_PI) * 2.0f), -1.0f)));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log1p(Float32(-u1)))) * cos(Float32(Float32(1.0) + fma(u2, Float32(Float32(pi) * Float32(2.0)), Float32(-1.0))))) end
\begin{array}{l}
\\
\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \cos \left(1 + \mathsf{fma}\left(u2, \pi \cdot 2, -1\right)\right)
\end{array}
Initial program 60.2%
sub-neg60.2%
log1p-def99.2%
Simplified99.2%
expm1-log1p-u99.1%
associate-*l*99.1%
Applied egg-rr99.1%
expm1-udef99.1%
log1p-udef99.1%
rem-exp-log99.1%
+-commutative99.1%
associate-*r*99.1%
*-commutative99.1%
*-commutative99.1%
Applied egg-rr99.1%
+-commutative99.1%
associate--l+99.2%
fma-neg99.2%
metadata-eval99.2%
Applied egg-rr99.2%
Final simplification99.2%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log1p (- u1)))) (cos (* u2 (* PI 2.0)))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-log1pf(-u1)) * cosf((u2 * (((float) M_PI) * 2.0f)));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log1p(Float32(-u1)))) * cos(Float32(u2 * Float32(Float32(pi) * Float32(2.0))))) end
\begin{array}{l}
\\
\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \cos \left(u2 \cdot \left(\pi \cdot 2\right)\right)
\end{array}
Initial program 60.2%
sub-neg60.2%
log1p-def99.2%
Simplified99.2%
Final simplification99.2%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (* u2 (* PI 2.0))))
(if (<= t_0 0.0005000000237487257)
(sqrt (- (log1p (- u1))))
(* (cos t_0) (sqrt (* u1 (- (- -1.0) (* u1 -0.5))))))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = u2 * (((float) M_PI) * 2.0f);
float tmp;
if (t_0 <= 0.0005000000237487257f) {
tmp = sqrtf(-log1pf(-u1));
} else {
tmp = cosf(t_0) * sqrtf((u1 * (-(-1.0f) - (u1 * -0.5f))));
}
return tmp;
}
function code(cosTheta_i, u1, u2) t_0 = Float32(u2 * Float32(Float32(pi) * Float32(2.0))) tmp = Float32(0.0) if (t_0 <= Float32(0.0005000000237487257)) tmp = sqrt(Float32(-log1p(Float32(-u1)))); else tmp = Float32(cos(t_0) * sqrt(Float32(u1 * Float32(Float32(-Float32(-1.0)) - Float32(u1 * Float32(-0.5)))))); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := u2 \cdot \left(\pi \cdot 2\right)\\
\mathbf{if}\;t_0 \leq 0.0005000000237487257:\\
\;\;\;\;\sqrt{-\mathsf{log1p}\left(-u1\right)}\\
\mathbf{else}:\\
\;\;\;\;\cos t_0 \cdot \sqrt{u1 \cdot \left(\left(--1\right) - u1 \cdot -0.5\right)}\\
\end{array}
\end{array}
if (*.f32 (*.f32 2 (PI.f32)) u2) < 5.00000024e-4Initial program 60.4%
sub-neg60.4%
log1p-def99.6%
Simplified99.6%
Taylor expanded in u2 around 0 99.5%
if 5.00000024e-4 < (*.f32 (*.f32 2 (PI.f32)) u2) Initial program 59.8%
Taylor expanded in u1 around 0 86.7%
unpow286.7%
associate-*r*86.7%
distribute-rgt-out86.5%
Simplified86.5%
Final simplification94.3%
(FPCore (cosTheta_i u1 u2) :precision binary32 (if (<= (* u2 (* PI 2.0)) 0.023499999195337296) (sqrt (- (log1p (- u1)))) (* (sqrt u1) (cos (* PI (* u2 2.0))))))
float code(float cosTheta_i, float u1, float u2) {
float tmp;
if ((u2 * (((float) M_PI) * 2.0f)) <= 0.023499999195337296f) {
tmp = sqrtf(-log1pf(-u1));
} else {
tmp = sqrtf(u1) * cosf((((float) M_PI) * (u2 * 2.0f)));
}
return tmp;
}
function code(cosTheta_i, u1, u2) tmp = Float32(0.0) if (Float32(u2 * Float32(Float32(pi) * Float32(2.0))) <= Float32(0.023499999195337296)) tmp = sqrt(Float32(-log1p(Float32(-u1)))); else tmp = Float32(sqrt(u1) * cos(Float32(Float32(pi) * Float32(u2 * Float32(2.0))))); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;u2 \cdot \left(\pi \cdot 2\right) \leq 0.023499999195337296:\\
\;\;\;\;\sqrt{-\mathsf{log1p}\left(-u1\right)}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{u1} \cdot \cos \left(\pi \cdot \left(u2 \cdot 2\right)\right)\\
\end{array}
\end{array}
if (*.f32 (*.f32 2 (PI.f32)) u2) < 0.0234999992Initial program 59.9%
sub-neg59.9%
log1p-def99.5%
Simplified99.5%
Taylor expanded in u2 around 0 95.7%
if 0.0234999992 < (*.f32 (*.f32 2 (PI.f32)) u2) Initial program 60.9%
sub-neg60.9%
log1p-def98.2%
Simplified98.2%
log1p-expm1-u98.0%
log1p-udef97.6%
associate-*l*97.6%
Applied egg-rr97.6%
Taylor expanded in u1 around 0 73.3%
mul-1-neg73.3%
Simplified73.3%
Taylor expanded in u2 around inf 73.3%
*-commutative73.3%
associate-*r*73.3%
*-commutative73.3%
associate-*r*73.3%
Simplified73.3%
Final simplification90.1%
(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 60.2%
sub-neg60.2%
log1p-def99.2%
Simplified99.2%
Taylor expanded in u2 around 0 81.6%
Final simplification81.6%
(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 60.2%
sub-neg60.2%
log1p-def99.2%
Simplified99.2%
log1p-expm1-u99.1%
log1p-udef97.6%
associate-*l*97.6%
Applied egg-rr97.6%
Taylor expanded in u1 around 0 73.6%
mul-1-neg73.6%
Simplified73.6%
Taylor expanded in u2 around 0 64.9%
Final simplification64.9%
herbie shell --seed 2024019
(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))))