
(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 6 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 (cos (* (* 2.0 (PI)) u2))) (t_1 (- (log (- 1.0 u1)))))
(if (<= t_1 0.0001500000071246177)
(* (sqrt (/ (* (* (- (- u1) 1.0) u1) u1) (- u1))) t_0)
(* (sqrt t_1) t_0))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
t_1 := -\log \left(1 - u1\right)\\
\mathbf{if}\;t\_1 \leq 0.0001500000071246177:\\
\;\;\;\;\sqrt{\frac{\left(\left(\left(-u1\right) - 1\right) \cdot u1\right) \cdot u1}{-u1}} \cdot t\_0\\
\mathbf{else}:\\
\;\;\;\;\sqrt{t\_1} \cdot t\_0\\
\end{array}
\end{array}
if (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1))) < 1.50000007e-4Initial program 33.8%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3294.0
Applied rewrites94.0%
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
lower-/.f32N/A
metadata-evalN/A
lower--.f32N/A
lower-*.f32N/A
lower-+.f3294.0
Applied rewrites94.0%
Taylor expanded in u1 around 0
*-commutativeN/A
unpow2N/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
lower--.f32N/A
mul-1-negN/A
lower-neg.f3294.0
Applied rewrites94.0%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3294.0
Applied rewrites94.0%
if 1.50000007e-4 < (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1))) Initial program 90.3%
Final simplification92.7%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (cos (* (* 2.0 (PI)) u2))))
(if (<= (* (sqrt (- (log (- 1.0 u1)))) t_0) 0.017999999225139618)
(* (sqrt (/ (* (* (- (- u1) 1.0) u1) u1) (- u1))) t_0)
(* (sqrt (log (sqrt (/ 1.0 (- 1.0 u1))))) (sqrt 2.0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\mathbf{if}\;\sqrt{-\log \left(1 - u1\right)} \cdot t\_0 \leq 0.017999999225139618:\\
\;\;\;\;\sqrt{\frac{\left(\left(\left(-u1\right) - 1\right) \cdot u1\right) \cdot u1}{-u1}} \cdot t\_0\\
\mathbf{else}:\\
\;\;\;\;\sqrt{\log \left(\sqrt{\frac{1}{1 - u1}}\right)} \cdot \sqrt{2}\\
\end{array}
\end{array}
if (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) < 0.0179999992Initial program 36.6%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3292.0
Applied rewrites92.0%
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
lower-/.f32N/A
metadata-evalN/A
lower--.f32N/A
lower-*.f32N/A
lower-+.f3292.0
Applied rewrites92.0%
Taylor expanded in u1 around 0
*-commutativeN/A
unpow2N/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
lower--.f32N/A
mul-1-negN/A
lower-neg.f3292.1
Applied rewrites92.1%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3292.1
Applied rewrites92.1%
if 0.0179999992 < (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) Initial program 91.3%
lift-neg.f32N/A
lift-log.f32N/A
neg-logN/A
inv-powN/A
sqr-powN/A
log-prodN/A
lower-+.f32N/A
lower-log.f32N/A
lower-pow.f32N/A
metadata-evalN/A
lower-log.f32N/A
lower-pow.f32N/A
metadata-eval86.7
Applied rewrites86.7%
Taylor expanded in u2 around 0
lower-*.f32N/A
lower-sqrt.f32N/A
lower-log.f32N/A
lower-sqrt.f32N/A
lower-/.f32N/A
lower--.f32N/A
lower-sqrt.f3275.8
Applied rewrites75.8%
Final simplification86.9%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (cos (* (* 2.0 (PI)) u2))))
(if (<= (* (sqrt (- (log (- 1.0 u1)))) t_0) 0.017999999225139618)
(* (sqrt (/ (* (- u1) u1) (- u1))) t_0)
(* (sqrt (log (sqrt (/ 1.0 (- 1.0 u1))))) (sqrt 2.0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\mathbf{if}\;\sqrt{-\log \left(1 - u1\right)} \cdot t\_0 \leq 0.017999999225139618:\\
\;\;\;\;\sqrt{\frac{\left(-u1\right) \cdot u1}{-u1}} \cdot t\_0\\
\mathbf{else}:\\
\;\;\;\;\sqrt{\log \left(\sqrt{\frac{1}{1 - u1}}\right)} \cdot \sqrt{2}\\
\end{array}
\end{array}
if (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) < 0.0179999992Initial program 36.6%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3292.0
Applied rewrites92.0%
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
lower-/.f32N/A
metadata-evalN/A
lower--.f32N/A
lower-*.f32N/A
lower-+.f3292.0
Applied rewrites92.0%
Taylor expanded in u1 around 0
unpow2N/A
associate-*r*N/A
lower-*.f32N/A
mul-1-negN/A
lower-neg.f3292.0
Applied rewrites92.0%
if 0.0179999992 < (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) Initial program 91.3%
lift-neg.f32N/A
lift-log.f32N/A
neg-logN/A
inv-powN/A
sqr-powN/A
log-prodN/A
lower-+.f32N/A
lower-log.f32N/A
lower-pow.f32N/A
metadata-evalN/A
lower-log.f32N/A
lower-pow.f32N/A
metadata-eval86.7
Applied rewrites86.7%
Taylor expanded in u2 around 0
lower-*.f32N/A
lower-sqrt.f32N/A
lower-log.f32N/A
lower-sqrt.f32N/A
lower-/.f32N/A
lower--.f32N/A
lower-sqrt.f3275.8
Applied rewrites75.8%
Final simplification86.8%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (* (fma -0.5 u1 1.0) u1) (* (- u1) u1))) (cos (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\sqrt{\mathsf{fma}\left(-0.5, u1, 1\right) \cdot u1 - \left(-u1\right) \cdot u1} \cdot \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
Initial program 54.1%
Applied rewrites49.6%
Taylor expanded in u1 around 0
unpow2N/A
associate-*r*N/A
lower-*.f32N/A
mul-1-negN/A
lower-neg.f3253.2
Applied rewrites52.0%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
+-commutativeN/A
lower-fma.f3261.0
Applied rewrites60.7%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (cos (* (* (PI) u2) 2.0)) (sqrt u1)))
\begin{array}{l}
\\
\cos \left(\left(\mathsf{PI}\left(\right) \cdot u2\right) \cdot 2\right) \cdot \sqrt{u1}
\end{array}
Initial program 54.1%
Applied rewrites48.6%
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.f3278.7
Applied rewrites78.7%
(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(u1) * Float32(1.0)) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(u1) * single(1.0); end
\begin{array}{l}
\\
\sqrt{u1} \cdot 1
\end{array}
Initial program 54.1%
Applied rewrites46.6%
Taylor expanded in u2 around 0
Applied rewrites8.3%
Taylor expanded in u1 around 0
lower-sqrt.f3266.5
Applied rewrites66.5%
herbie shell --seed 2024302
(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))))