
(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 (exp (log (* 2.0 (* PI u2)))))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-log1pf(-u1)) * cosf(expf(logf((2.0f * (((float) M_PI) * u2)))));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log1p(Float32(-u1)))) * cos(exp(log(Float32(Float32(2.0) * Float32(Float32(pi) * u2)))))) end
\begin{array}{l}
\\
\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \cos \left(e^{\log \left(2 \cdot \left(\pi \cdot u2\right)\right)}\right)
\end{array}
Initial program 61.0%
sub-neg61.0%
log1p-define99.0%
Simplified99.0%
add-exp-log99.0%
associate-*l*99.0%
Applied egg-rr99.0%
Final simplification99.0%
(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 61.0%
sub-neg61.0%
log1p-define99.0%
Simplified99.0%
Final simplification99.0%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (* u2 (* 2.0 PI))))
(if (<= t_0 0.0024999999441206455)
(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 * (2.0f * ((float) M_PI));
float tmp;
if (t_0 <= 0.0024999999441206455f) {
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(2.0) * Float32(pi))) tmp = Float32(0.0) if (t_0 <= Float32(0.0024999999441206455)) 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(2 \cdot \pi\right)\\
\mathbf{if}\;t\_0 \leq 0.0024999999441206455:\\
\;\;\;\;\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) < 0.00249999994Initial program 64.1%
sub-neg64.1%
log1p-define99.3%
Simplified99.3%
Taylor expanded in u2 around 0 97.8%
if 0.00249999994 < (*.f32 (*.f32 2 (PI.f32)) u2) Initial program 56.1%
Taylor expanded in u1 around 0 87.2%
*-commutative87.2%
*-commutative87.2%
unpow287.2%
associate-*l*87.2%
distribute-lft-out87.1%
Simplified87.1%
Final simplification93.7%
(FPCore (cosTheta_i u1 u2) :precision binary32 (if (<= (* u2 (* 2.0 PI)) 0.0024999999441206455) (sqrt (- (log1p (- u1)))) (* (sqrt u1) (cos (* 2.0 (* PI u2))))))
float code(float cosTheta_i, float u1, float u2) {
float tmp;
if ((u2 * (2.0f * ((float) M_PI))) <= 0.0024999999441206455f) {
tmp = sqrtf(-log1pf(-u1));
} else {
tmp = sqrtf(u1) * cosf((2.0f * (((float) M_PI) * u2)));
}
return tmp;
}
function code(cosTheta_i, u1, u2) tmp = Float32(0.0) if (Float32(u2 * Float32(Float32(2.0) * Float32(pi))) <= Float32(0.0024999999441206455)) tmp = sqrt(Float32(-log1p(Float32(-u1)))); else tmp = Float32(sqrt(u1) * cos(Float32(Float32(2.0) * Float32(Float32(pi) * u2)))); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;u2 \cdot \left(2 \cdot \pi\right) \leq 0.0024999999441206455:\\
\;\;\;\;\sqrt{-\mathsf{log1p}\left(-u1\right)}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{u1} \cdot \cos \left(2 \cdot \left(\pi \cdot u2\right)\right)\\
\end{array}
\end{array}
if (*.f32 (*.f32 2 (PI.f32)) u2) < 0.00249999994Initial program 64.1%
sub-neg64.1%
log1p-define99.3%
Simplified99.3%
Taylor expanded in u2 around 0 97.8%
if 0.00249999994 < (*.f32 (*.f32 2 (PI.f32)) u2) Initial program 56.1%
add-sqr-sqrt48.8%
pow248.8%
Applied egg-rr65.1%
Taylor expanded in u1 around 0 76.3%
Final simplification89.6%
(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 61.0%
sub-neg61.0%
log1p-define99.0%
Simplified99.0%
Taylor expanded in u2 around 0 78.0%
Final simplification78.0%
(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 61.0%
sub-neg61.0%
log1p-define99.0%
Simplified99.0%
Taylor expanded in u2 around 0 78.0%
add-cbrt-cube78.0%
pow1/376.2%
Applied egg-rr59.1%
unpow1/359.8%
Simplified59.8%
Taylor expanded in u1 around 0 61.4%
Final simplification61.4%
herbie shell --seed 2024050
(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))))