
(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)))) (+ 1.0 (+ (cos (* PI (* u2 2.0))) -1.0))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-log1pf(-u1)) * (1.0f + (cosf((((float) M_PI) * (u2 * 2.0f))) + -1.0f));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log1p(Float32(-u1)))) * Float32(Float32(1.0) + Float32(cos(Float32(Float32(pi) * Float32(u2 * Float32(2.0)))) + Float32(-1.0)))) end
\begin{array}{l}
\\
\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \left(1 + \left(\cos \left(\pi \cdot \left(u2 \cdot 2\right)\right) + -1\right)\right)
\end{array}
Initial program 56.1%
sub-neg56.1%
log1p-def99.2%
Simplified99.2%
log1p-expm1-u99.1%
associate-*l*99.1%
Applied egg-rr99.1%
expm1-log1p-u98.9%
expm1-udef98.8%
log1p-expm1-u98.8%
log1p-udef98.8%
rem-exp-log98.8%
+-commutative98.8%
associate-*r*98.8%
*-commutative98.8%
Applied egg-rr98.8%
+-commutative98.8%
*-commutative98.8%
associate-*r*98.8%
associate--l+99.2%
sub-neg99.2%
*-commutative99.2%
associate-*l*99.2%
metadata-eval99.2%
Applied egg-rr99.2%
Final simplification99.2%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (cos (* u2 (* PI 2.0)))))
(if (<= t_0 0.9999600052833557)
(* 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 * (((float) M_PI) * 2.0f)));
float tmp;
if (t_0 <= 0.9999600052833557f) {
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(pi) * Float32(2.0)))) tmp = Float32(0.0) if (t_0 <= Float32(0.9999600052833557)) 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(u2 \cdot \left(\pi \cdot 2\right)\right)\\
\mathbf{if}\;t_0 \leq 0.9999600052833557:\\
\;\;\;\;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)) < 0.999960005Initial program 54.8%
Taylor expanded in u1 around 0 90.6%
*-commutative90.6%
*-commutative90.6%
unpow290.6%
associate-*l*90.6%
distribute-lft-out90.6%
Simplified90.6%
if 0.999960005 < (cos.f32 (*.f32 (*.f32 2 (PI.f32)) u2)) Initial program 56.7%
sub-neg56.7%
log1p-def99.4%
Simplified99.4%
Taylor expanded in u2 around 0 96.8%
Final simplification94.9%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (cos (* u2 (* PI 2.0)))))
(if (<= t_0 0.9999499917030334)
(* t_0 (sqrt u1))
(sqrt (- (log1p (- u1)))))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = cosf((u2 * (((float) M_PI) * 2.0f)));
float tmp;
if (t_0 <= 0.9999499917030334f) {
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(pi) * Float32(2.0)))) tmp = Float32(0.0) if (t_0 <= Float32(0.9999499917030334)) 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(\pi \cdot 2\right)\right)\\
\mathbf{if}\;t_0 \leq 0.9999499917030334:\\
\;\;\;\;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)) < 0.999949992Initial program 54.3%
Taylor expanded in u1 around 0 79.1%
mul-1-neg79.1%
Simplified79.1%
if 0.999949992 < (cos.f32 (*.f32 (*.f32 2 (PI.f32)) u2)) Initial program 56.9%
sub-neg56.9%
log1p-def99.4%
Simplified99.4%
Taylor expanded in u2 around 0 96.7%
Final simplification91.3%
(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 56.1%
sub-neg56.1%
log1p-def99.2%
Simplified99.2%
Final simplification99.2%
(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 56.1%
sub-neg56.1%
log1p-def99.2%
Simplified99.2%
Taylor expanded in u2 around 0 79.3%
Final simplification79.3%
(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 56.1%
sub-neg56.1%
log1p-def99.2%
Simplified99.2%
Taylor expanded in u2 around 0 79.3%
add-cbrt-cube79.3%
pow1/377.1%
Applied egg-rr62.9%
Taylor expanded in u1 around 0 65.4%
Final simplification65.4%
herbie shell --seed 2023309
(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))))