
(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 7 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 (let* ((t_0 (* u2 (* 2.0 PI))) (t_1 (+ 2.0 t_0))) (* (sqrt (- (log1p (- u1)))) (cos (/ (* t_0 t_1) t_1)))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = u2 * (2.0f * ((float) M_PI));
float t_1 = 2.0f + t_0;
return sqrtf(-log1pf(-u1)) * cosf(((t_0 * t_1) / t_1));
}
function code(cosTheta_i, u1, u2) t_0 = Float32(u2 * Float32(Float32(2.0) * Float32(pi))) t_1 = Float32(Float32(2.0) + t_0) return Float32(sqrt(Float32(-log1p(Float32(-u1)))) * cos(Float32(Float32(t_0 * t_1) / t_1))) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := u2 \cdot \left(2 \cdot \pi\right)\\
t_1 := 2 + t_0\\
\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \cos \left(\frac{t_0 \cdot t_1}{t_1}\right)
\end{array}
\end{array}
Initial program 58.7%
sub-neg58.7%
log1p-def99.3%
Simplified99.3%
expm1-log1p-u99.3%
associate-*l*99.3%
Applied egg-rr99.3%
expm1-udef99.3%
flip--99.2%
Applied egg-rr99.2%
difference-of-sqr-199.3%
+-commutative99.3%
+-commutative99.3%
associate-+r+99.3%
metadata-eval99.3%
associate--l+99.3%
metadata-eval99.3%
+-rgt-identity99.3%
+-commutative99.3%
+-commutative99.3%
associate-+r+99.3%
metadata-eval99.3%
Simplified99.3%
Final simplification99.3%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (* u2 (* 2.0 PI))))
(*
(sqrt (- (log1p (- u1))))
(cos (+ (+ (* (* t_0 t_0) (/ 0.5 (* u2 PI))) 1.0) -1.0)))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = u2 * (2.0f * ((float) M_PI));
return sqrtf(-log1pf(-u1)) * cosf(((((t_0 * t_0) * (0.5f / (u2 * ((float) M_PI)))) + 1.0f) + -1.0f));
}
function code(cosTheta_i, u1, u2) t_0 = Float32(u2 * Float32(Float32(2.0) * Float32(pi))) return Float32(sqrt(Float32(-log1p(Float32(-u1)))) * cos(Float32(Float32(Float32(Float32(t_0 * t_0) * Float32(Float32(0.5) / Float32(u2 * Float32(pi)))) + Float32(1.0)) + Float32(-1.0)))) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := u2 \cdot \left(2 \cdot \pi\right)\\
\sqrt{-\mathsf{log1p}\left(-u1\right)} \cdot \cos \left(\left(\left(t_0 \cdot t_0\right) \cdot \frac{0.5}{u2 \cdot \pi} + 1\right) + -1\right)
\end{array}
\end{array}
Initial program 58.7%
sub-neg58.7%
log1p-def99.3%
Simplified99.3%
expm1-log1p-u99.3%
associate-*l*99.3%
Applied egg-rr99.3%
expm1-udef99.3%
log1p-udef99.2%
rem-exp-log99.3%
+-commutative99.3%
associate-*r*99.3%
*-commutative99.3%
*-commutative99.3%
Applied egg-rr99.3%
+-rgt-identity99.3%
flip-+99.3%
pow299.3%
*-commutative99.3%
*-commutative99.3%
associate-*l*99.3%
metadata-eval99.3%
*-commutative99.3%
*-commutative99.3%
associate-*l*99.3%
Applied egg-rr99.3%
--rgt-identity99.3%
--rgt-identity99.3%
remove-double-div99.3%
associate-/r/99.3%
unpow299.3%
associate-*r/99.3%
/-rgt-identity99.3%
unpow299.3%
*-commutative99.3%
*-commutative99.3%
associate-*l*99.3%
associate-/r*99.3%
metadata-eval99.3%
*-commutative99.3%
Simplified99.3%
unpow299.3%
Applied egg-rr99.3%
Final simplification99.3%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (cos (* u2 (* 2.0 PI)))))
(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 * (2.0f * ((float) M_PI))));
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(2.0) * Float32(pi)))) 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(2 \cdot \pi\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 59.7%
add-cube-cbrt59.6%
pow359.6%
add-sqr-sqrt59.6%
sqrt-unprod59.6%
sqr-neg59.6%
sqrt-unprod1.3%
add-sqr-sqrt1.3%
sub-neg1.3%
log1p-udef-0.0%
add-sqr-sqrt-0.0%
sqrt-unprod74.0%
sqr-neg74.0%
sqrt-unprod74.0%
add-sqr-sqrt74.0%
Applied egg-rr74.0%
Taylor expanded in u1 around 0 76.3%
if 0.999949992 < (cos.f32 (*.f32 (*.f32 2 (PI.f32)) u2)) Initial program 58.3%
sub-neg58.3%
log1p-def99.5%
Simplified99.5%
Taylor expanded in u2 around 0 96.5%
Final simplification91.0%
(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 58.7%
sub-neg58.7%
log1p-def99.3%
Simplified99.3%
Final simplification99.3%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (* u2 (* 2.0 PI))))
(if (<= t_0 0.0013800000306218863)
(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 <= 0.0013800000306218863f) {
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(0.0013800000306218863)) 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 0.0013800000306218863:\\
\;\;\;\;\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) < 0.00138000003Initial program 57.6%
sub-neg57.6%
log1p-def99.6%
Simplified99.6%
Taylor expanded in u2 around 0 99.0%
if 0.00138000003 < (*.f32 (*.f32 2 (PI.f32)) u2) Initial program 60.4%
Taylor expanded in u1 around 0 88.3%
unpow288.3%
associate-*r*88.3%
distribute-rgt-out88.2%
Simplified88.2%
Final simplification95.0%
(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 58.7%
sub-neg58.7%
log1p-def99.3%
Simplified99.3%
Taylor expanded in u2 around 0 81.5%
Final simplification81.5%
(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 58.7%
add-sqr-sqrt55.9%
sqrt-unprod56.2%
swap-sqr56.2%
Applied egg-rr71.0%
associate-*r*71.0%
*-commutative71.0%
associate-*l*71.0%
Simplified71.0%
Taylor expanded in u2 around 0 37.0%
log1p-def64.1%
Simplified64.1%
Taylor expanded in u1 around 0 65.6%
Final simplification65.6%
herbie shell --seed 2024018
(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))))