
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log (- 1.0 u1)))) (cos (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 8 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log (- 1.0 u1)))) (cos (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (pow (PI) 0.25)))
(if (<= (- 1.0 u1) 0.9998940229415894)
(*
(cos (* (* (* 2.0 (* u2 (sqrt (PI)))) t_0) t_0))
(sqrt (- (log (- 1.0 u1)))))
(* (cos (* (* 2.0 (PI)) u2)) (pow (* u1 u1) 0.25)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := {\mathsf{PI}\left(\right)}^{0.25}\\
\mathbf{if}\;1 - u1 \leq 0.9998940229415894:\\
\;\;\;\;\cos \left(\left(\left(2 \cdot \left(u2 \cdot \sqrt{\mathsf{PI}\left(\right)}\right)\right) \cdot t\_0\right) \cdot t\_0\right) \cdot \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{else}:\\
\;\;\;\;\cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right) \cdot {\left(u1 \cdot u1\right)}^{0.25}\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.999894023Initial program 89.3%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
lift-PI.f32N/A
add-sqr-sqrtN/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
lower-*.f32N/A
lift-PI.f32N/A
lower-sqrt.f32N/A
lift-PI.f32N/A
lower-sqrt.f3289.3
Applied rewrites89.3%
lift-*.f32N/A
*-commutativeN/A
lift-sqrt.f32N/A
pow1/2N/A
metadata-evalN/A
sqr-powN/A
associate-*l*N/A
lower-*.f32N/A
metadata-evalN/A
metadata-evalN/A
lower-pow.f32N/A
lower-*.f32N/A
metadata-evalN/A
metadata-evalN/A
lower-pow.f3289.3
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
lower-*.f32N/A
Applied rewrites89.3%
if 0.999894023 < (-.f32 #s(literal 1 binary32) u1) Initial program 33.9%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3294.1
Applied rewrites94.1%
lift-sqrt.f32N/A
pow1/2N/A
metadata-evalN/A
pow-sqrN/A
pow-prod-downN/A
lower-pow.f32N/A
lower-*.f3294.1
Applied rewrites94.1%
Taylor expanded in u1 around 0
unpow2N/A
lower-*.f3294.1
Applied rewrites94.1%
Final simplification92.3%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (sqrt (PI))))
(if (<= (- 1.0 u1) 0.9998940229415894)
(* (cos (* (* (* 2.0 u2) t_0) t_0)) (sqrt (- (log (- 1.0 u1)))))
(* (cos (* (* 2.0 (PI)) u2)) (pow (* u1 u1) 0.25)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{\mathsf{PI}\left(\right)}\\
\mathbf{if}\;1 - u1 \leq 0.9998940229415894:\\
\;\;\;\;\cos \left(\left(\left(2 \cdot u2\right) \cdot t\_0\right) \cdot t\_0\right) \cdot \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{else}:\\
\;\;\;\;\cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right) \cdot {\left(u1 \cdot u1\right)}^{0.25}\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.999894023Initial program 89.3%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
lift-PI.f32N/A
add-sqr-sqrtN/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
lower-*.f32N/A
lift-PI.f32N/A
lower-sqrt.f32N/A
lift-PI.f32N/A
lower-sqrt.f3289.3
Applied rewrites89.3%
if 0.999894023 < (-.f32 #s(literal 1 binary32) u1) Initial program 33.9%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3294.1
Applied rewrites94.1%
lift-sqrt.f32N/A
pow1/2N/A
metadata-evalN/A
pow-sqrN/A
pow-prod-downN/A
lower-pow.f32N/A
lower-*.f3294.1
Applied rewrites94.1%
Taylor expanded in u1 around 0
unpow2N/A
lower-*.f3294.1
Applied rewrites94.1%
Final simplification92.3%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (cos (* (* 2.0 (PI)) u2))))
(if (<= (- 1.0 u1) 0.9998940229415894)
(* t_0 (sqrt (- (log (- 1.0 u1)))))
(* t_0 (pow (* u1 u1) 0.25)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\mathbf{if}\;1 - u1 \leq 0.9998940229415894:\\
\;\;\;\;t\_0 \cdot \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{else}:\\
\;\;\;\;t\_0 \cdot {\left(u1 \cdot u1\right)}^{0.25}\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.999894023Initial program 89.3%
if 0.999894023 < (-.f32 #s(literal 1 binary32) u1) Initial program 33.9%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3294.1
Applied rewrites94.1%
lift-sqrt.f32N/A
pow1/2N/A
metadata-evalN/A
pow-sqrN/A
pow-prod-downN/A
lower-pow.f32N/A
lower-*.f3294.1
Applied rewrites94.1%
Taylor expanded in u1 around 0
unpow2N/A
lower-*.f3294.1
Applied rewrites94.1%
Final simplification92.3%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (cos (* (* 2.0 (PI)) u2)) (pow (* u1 u1) 0.25)))
\begin{array}{l}
\\
\cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right) \cdot {\left(u1 \cdot u1\right)}^{0.25}
\end{array}
Initial program 55.3%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3278.3
Applied rewrites78.3%
lift-sqrt.f32N/A
pow1/2N/A
metadata-evalN/A
pow-sqrN/A
pow-prod-downN/A
lower-pow.f32N/A
lower-*.f3278.4
Applied rewrites78.4%
Taylor expanded in u1 around 0
unpow2N/A
lower-*.f3278.4
Applied rewrites78.4%
Final simplification78.4%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt u1) (cos (* (* u2 (PI)) 2.0))))
\begin{array}{l}
\\
\sqrt{u1} \cdot \cos \left(\left(u2 \cdot \mathsf{PI}\left(\right)\right) \cdot 2\right)
\end{array}
Initial program 55.3%
Applied rewrites47.2%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower-cos.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f32N/A
lower-sqrt.f3278.3
Applied rewrites78.3%
Final simplification78.3%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* 1.0 (pow (* u1 u1) 0.25)))
float code(float cosTheta_i, float u1, float u2) {
return 1.0f * 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 = 1.0e0 * ((u1 * u1) ** 0.25e0)
end function
function code(cosTheta_i, u1, u2) return Float32(Float32(1.0) * (Float32(u1 * u1) ^ Float32(0.25))) end
function tmp = code(cosTheta_i, u1, u2) tmp = single(1.0) * ((u1 * u1) ^ single(0.25)); end
\begin{array}{l}
\\
1 \cdot {\left(u1 \cdot u1\right)}^{0.25}
\end{array}
Initial program 55.3%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3278.3
Applied rewrites78.3%
lift-sqrt.f32N/A
pow1/2N/A
metadata-evalN/A
pow-sqrN/A
pow-prod-downN/A
lower-pow.f32N/A
lower-*.f3278.4
Applied rewrites78.4%
Taylor expanded in u1 around 0
unpow2N/A
lower-*.f3278.4
Applied rewrites78.4%
Taylor expanded in u2 around 0
Applied rewrites67.0%
Final simplification67.0%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (- u1))) 1.0))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-(-u1)) * 1.0f;
}
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)) * 1.0e0
end function
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-Float32(-u1))) * Float32(1.0)) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(-(-u1)) * single(1.0); end
\begin{array}{l}
\\
\sqrt{-\left(-u1\right)} \cdot 1
\end{array}
Initial program 55.3%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3278.3
Applied rewrites78.3%
Taylor expanded in u2 around 0
Applied rewrites67.0%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (- (sqrt u1)) 1.0))
float code(float cosTheta_i, float u1, float u2) {
return -sqrtf(u1) * 1.0f;
}
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) * 1.0e0
end function
function code(cosTheta_i, u1, u2) return Float32(Float32(-sqrt(u1)) * Float32(1.0)) end
function tmp = code(cosTheta_i, u1, u2) tmp = -sqrt(u1) * single(1.0); end
\begin{array}{l}
\\
\left(-\sqrt{u1}\right) \cdot 1
\end{array}
Initial program 55.3%
Taylor expanded in u1 around 0
*-commutativeN/A
unpow2N/A
rem-square-sqrtN/A
mul-1-negN/A
lower-neg.f32N/A
lower-sqrt.f323.5
Applied rewrites3.5%
Taylor expanded in u2 around 0
Applied rewrites4.9%
herbie shell --seed 2024332
(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))))