
(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 (* 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 63.3%
sub-neg63.3%
log1p-def99.1%
associate-*l*99.1%
Simplified99.1%
Final simplification99.1%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (* u2 (* 2.0 PI))))
(if (<= t_0 0.010999999940395355)
(sqrt (- (log1p (- u1))))
(* (sqrt u1) (cos t_0)))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = u2 * (2.0f * ((float) M_PI));
float tmp;
if (t_0 <= 0.010999999940395355f) {
tmp = sqrtf(-log1pf(-u1));
} else {
tmp = sqrtf(u1) * cosf(t_0);
}
return tmp;
}
function code(cosTheta_i, u1, u2) t_0 = Float32(u2 * Float32(Float32(2.0) * Float32(pi))) tmp = Float32(0.0) if (t_0 <= Float32(0.010999999940395355)) tmp = sqrt(Float32(-log1p(Float32(-u1)))); else tmp = Float32(sqrt(u1) * cos(t_0)); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := u2 \cdot \left(2 \cdot \pi\right)\\
\mathbf{if}\;t_0 \leq 0.010999999940395355:\\
\;\;\;\;\sqrt{-\mathsf{log1p}\left(-u1\right)}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{u1} \cdot \cos t_0\\
\end{array}
\end{array}
if (*.f32 (*.f32 2 (PI.f32)) u2) < 0.0109999999Initial program 64.7%
sub-neg64.7%
log1p-def99.3%
associate-*l*99.3%
Simplified99.3%
Taylor expanded in u2 around 0 96.5%
if 0.0109999999 < (*.f32 (*.f32 2 (PI.f32)) u2) Initial program 59.6%
add-sqr-sqrt59.5%
pow259.5%
pow1/259.5%
sqrt-pow159.7%
add-sqr-sqrt59.5%
sqrt-unprod59.7%
sqr-neg59.7%
sqrt-unprod1.5%
add-sqr-sqrt1.5%
sub-neg1.5%
log1p-udef-0.0%
add-sqr-sqrt-0.0%
sqrt-unprod71.6%
sqr-neg71.6%
sqrt-unprod71.7%
add-sqr-sqrt71.6%
metadata-eval71.6%
Applied egg-rr71.6%
Taylor expanded in u1 around 0 73.8%
Final simplification90.2%
(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 63.3%
sub-neg63.3%
log1p-def99.1%
associate-*l*99.1%
Simplified99.1%
Taylor expanded in u2 around 0 80.1%
Final simplification80.1%
(FPCore (cosTheta_i u1 u2) :precision binary32 (sqrt (- u1 (* -0.5 (* u1 u1)))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf((u1 - (-0.5f * (u1 * 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 - ((-0.5e0) * (u1 * u1))))
end function
function code(cosTheta_i, u1, u2) return sqrt(Float32(u1 - Float32(Float32(-0.5) * Float32(u1 * u1)))) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt((u1 - (single(-0.5) * (u1 * u1)))); end
\begin{array}{l}
\\
\sqrt{u1 - -0.5 \cdot \left(u1 \cdot u1\right)}
\end{array}
Initial program 63.3%
sub-neg63.3%
log1p-def99.1%
associate-*l*99.1%
Simplified99.1%
Taylor expanded in u2 around 0 80.1%
Taylor expanded in u1 around 0 70.7%
+-commutative70.7%
mul-1-neg70.7%
unsub-neg70.7%
unpow270.7%
Simplified70.7%
Final simplification70.7%
(FPCore (cosTheta_i u1 u2) :precision binary32 (pow (* u1 u1) 0.25))
float code(float cosTheta_i, float u1, float u2) {
return powf((u1 * u1), 0.25f);
}
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 = (u1 * u1) ** 0.25e0
end function
function code(cosTheta_i, u1, u2) return Float32(u1 * u1) ^ Float32(0.25) end
function tmp = code(cosTheta_i, u1, u2) tmp = (u1 * u1) ^ single(0.25); end
\begin{array}{l}
\\
{\left(u1 \cdot u1\right)}^{0.25}
\end{array}
Initial program 63.3%
sub-neg63.3%
log1p-def99.1%
associate-*l*99.1%
Simplified99.1%
Taylor expanded in u2 around 0 80.1%
pow1/280.1%
add-sqr-sqrt80.1%
sqrt-unprod80.1%
sqr-neg80.1%
sqrt-unprod-0.0%
add-sqr-sqrt-0.0%
add-sqr-sqrt-0.0%
sqrt-unprod60.3%
sqr-neg60.3%
sqrt-unprod60.3%
add-sqr-sqrt60.3%
metadata-eval60.3%
pow-prod-up60.2%
pow-prod-down60.3%
pow260.3%
Applied egg-rr60.3%
Taylor expanded in u1 around 0 61.9%
unpow261.9%
Simplified61.9%
Final simplification61.9%
(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 63.3%
sub-neg63.3%
log1p-def99.1%
associate-*l*99.1%
Simplified99.1%
Taylor expanded in u2 around 0 80.1%
pow1/280.1%
add-sqr-sqrt80.1%
sqrt-unprod80.1%
sqr-neg80.1%
sqrt-unprod-0.0%
add-sqr-sqrt-0.0%
add-sqr-sqrt-0.0%
sqrt-unprod60.3%
sqr-neg60.3%
sqrt-unprod60.3%
add-sqr-sqrt60.3%
metadata-eval60.3%
pow-prod-up60.2%
pow-prod-down60.3%
pow260.3%
Applied egg-rr60.3%
Taylor expanded in u1 around 0 61.9%
Final simplification61.9%
herbie shell --seed 2023188
(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))))