
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log (- 1.0 u1)))) (sin (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \sin \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)))) (sin (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (cbrt (PI))))
(if (<= (- 1.0 u1) 0.9998350143432617)
(* (sin (* (* (* u2 t_0) 2.0) (pow t_0 2.0))) (sqrt (- (log (- 1.0 u1)))))
(*
(sin (* (* 2.0 (PI)) u2))
(sqrt (/ (* (- u1) (- u1)) (/ -1.0 (/ 1.0 (- u1)))))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt[3]{\mathsf{PI}\left(\right)}\\
\mathbf{if}\;1 - u1 \leq 0.9998350143432617:\\
\;\;\;\;\sin \left(\left(\left(u2 \cdot t\_0\right) \cdot 2\right) \cdot {t\_0}^{2}\right) \cdot \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{else}:\\
\;\;\;\;\sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right) \cdot \sqrt{\frac{\left(-u1\right) \cdot \left(-u1\right)}{\frac{-1}{\frac{1}{-u1}}}}\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.99983501Initial program 87.7%
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
*-commutativeN/A
lift-PI.f32N/A
add-cube-cbrtN/A
associate-*l*N/A
associate-*l*N/A
lower-*.f32N/A
pow2N/A
lower-pow.f32N/A
lift-PI.f32N/A
lower-cbrt.f32N/A
lower-*.f32N/A
lower-*.f32N/A
lift-PI.f32N/A
lower-cbrt.f3287.8
Applied rewrites87.8%
if 0.99983501 < (-.f32 #s(literal 1 binary32) u1) Initial program 35.0%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3292.5
Applied rewrites92.5%
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
lower-/.f32N/A
metadata-evalN/A
lower--.f32N/A
lower-*.f32N/A
lower-+.f3292.6
Applied rewrites92.6%
lift-+.f32N/A
flip3-+N/A
clear-numN/A
Applied rewrites92.6%
Final simplification90.7%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (- (log (- 1.0 u1)))) (t_1 (sin (* (* 2.0 (PI)) u2))))
(if (<= t_0 0.00016500000492669642)
(* t_1 (sqrt (/ (* (- u1) (- u1)) (/ -1.0 (/ 1.0 (- u1))))))
(* t_1 (sqrt t_0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := -\log \left(1 - u1\right)\\
t_1 := \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\mathbf{if}\;t\_0 \leq 0.00016500000492669642:\\
\;\;\;\;t\_1 \cdot \sqrt{\frac{\left(-u1\right) \cdot \left(-u1\right)}{\frac{-1}{\frac{1}{-u1}}}}\\
\mathbf{else}:\\
\;\;\;\;t\_1 \cdot \sqrt{t\_0}\\
\end{array}
\end{array}
if (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1))) < 1.65000005e-4Initial program 35.0%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3292.5
Applied rewrites92.5%
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
lower-/.f32N/A
metadata-evalN/A
lower--.f32N/A
lower-*.f32N/A
lower-+.f3292.6
Applied rewrites92.6%
lift-+.f32N/A
flip3-+N/A
clear-numN/A
Applied rewrites92.6%
if 1.65000005e-4 < (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1))) Initial program 87.7%
Final simplification90.7%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (* (* 2.0 (PI)) u2)))
(if (<= (- 1.0 u1) 0.9995200037956238)
(* t_0 (sqrt (- (log (- 1.0 u1)))))
(* (sin t_0) (sqrt (/ (* (- u1) (- u1)) (/ -1.0 (/ 1.0 (- u1)))))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\\
\mathbf{if}\;1 - u1 \leq 0.9995200037956238:\\
\;\;\;\;t\_0 \cdot \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{else}:\\
\;\;\;\;\sin t\_0 \cdot \sqrt{\frac{\left(-u1\right) \cdot \left(-u1\right)}{\frac{-1}{\frac{1}{-u1}}}}\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.999520004Initial program 90.1%
Taylor expanded in u2 around 0
*-commutativeN/A
associate-*r*N/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3273.0
Applied rewrites73.0%
if 0.999520004 < (-.f32 #s(literal 1 binary32) u1) Initial program 38.4%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3290.5
Applied rewrites90.5%
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
lower-/.f32N/A
metadata-evalN/A
lower--.f32N/A
lower-*.f32N/A
lower-+.f3290.6
Applied rewrites90.6%
lift-+.f32N/A
flip3-+N/A
clear-numN/A
Applied rewrites90.6%
Final simplification84.7%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (* (* 2.0 (PI)) u2)))
(if (<= (- 1.0 u1) 0.9995200037956238)
(* t_0 (sqrt (- (log (- 1.0 u1)))))
(* (sqrt (/ (* (- u1) u1) (- u1))) (sin t_0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\\
\mathbf{if}\;1 - u1 \leq 0.9995200037956238:\\
\;\;\;\;t\_0 \cdot \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{\frac{\left(-u1\right) \cdot u1}{-u1}} \cdot \sin t\_0\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.999520004Initial program 90.1%
Taylor expanded in u2 around 0
*-commutativeN/A
associate-*r*N/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3273.0
Applied rewrites73.0%
if 0.999520004 < (-.f32 #s(literal 1 binary32) u1) Initial program 38.4%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3290.5
Applied rewrites90.5%
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
lower-/.f32N/A
metadata-evalN/A
lower--.f32N/A
lower-*.f32N/A
lower-+.f3290.6
Applied rewrites90.6%
Taylor expanded in u1 around 0
mul-1-negN/A
unpow2N/A
distribute-lft-neg-inN/A
mul-1-negN/A
lower-*.f32N/A
mul-1-negN/A
lower-neg.f3290.6
Applied rewrites90.6%
Final simplification84.7%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (* (* 2.0 (PI)) u2)))
(if (<= (- 1.0 u1) 0.9995200037956238)
(* t_0 (sqrt (- (log (- 1.0 u1)))))
(* (sqrt u1) (sin t_0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\\
\mathbf{if}\;1 - u1 \leq 0.9995200037956238:\\
\;\;\;\;t\_0 \cdot \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{u1} \cdot \sin t\_0\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.999520004Initial program 90.1%
Taylor expanded in u2 around 0
*-commutativeN/A
associate-*r*N/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3273.0
Applied rewrites73.0%
if 0.999520004 < (-.f32 #s(literal 1 binary32) u1) Initial program 38.4%
Applied rewrites42.2%
Taylor expanded in u1 around 0
lower-sqrt.f3290.5
Applied rewrites90.5%
Final simplification84.7%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt u1) (sin (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\sqrt{u1} \cdot \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
Initial program 55.6%
Applied rewrites35.8%
Taylor expanded in u1 around 0
lower-sqrt.f3277.7
Applied rewrites77.7%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (* (* u2 (PI)) 2.0) (sqrt (- (- u1)))))
\begin{array}{l}
\\
\left(\left(u2 \cdot \mathsf{PI}\left(\right)\right) \cdot 2\right) \cdot \sqrt{-\left(-u1\right)}
\end{array}
Initial program 55.6%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3277.7
Applied rewrites77.7%
Taylor expanded in u2 around 0
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3267.2
Applied rewrites67.2%
Final simplification67.2%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (- (sqrt u1)) (* (* u2 (PI)) 2.0)))
\begin{array}{l}
\\
\left(-\sqrt{u1}\right) \cdot \left(\left(u2 \cdot \mathsf{PI}\left(\right)\right) \cdot 2\right)
\end{array}
Initial program 55.6%
Taylor expanded in u1 around 0
*-commutativeN/A
unpow2N/A
rem-square-sqrtN/A
mul-1-negN/A
lower-neg.f32N/A
lower-sqrt.f324.0
Applied rewrites4.0%
Taylor expanded in u2 around 0
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f324.4
Applied rewrites4.4%
Final simplification4.4%
herbie shell --seed 2024244
(FPCore (cosTheta_i u1 u2)
:name "Beckmann Sample, near normal, slope_y"
: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)))) (sin (* (* 2.0 (PI)) u2))))