
(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 7 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 (- (log (- 1.0 u1)))) (t_1 (sin (* (* 2.0 (PI)) u2))))
(if (<= t_0 0.00015500000154133886)
(* (pow (* u1 u1) 0.25) t_1)
(* (sqrt t_0) t_1))))\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 0.00015500000154133886:\\
\;\;\;\;{\left(u1 \cdot u1\right)}^{0.25} \cdot t\_1\\
\mathbf{else}:\\
\;\;\;\;\sqrt{t\_0} \cdot t\_1\\
\end{array}
\end{array}
if (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1))) < 1.55000002e-4Initial program 34.4%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3293.5
Applied rewrites93.5%
lift-sqrt.f32N/A
pow1/2N/A
metadata-evalN/A
pow-prod-upN/A
pow-prod-downN/A
lower-pow.f32N/A
lower-*.f3293.6
Applied rewrites93.6%
Taylor expanded in u1 around 0
unpow2N/A
lower-*.f3293.6
Applied rewrites93.6%
if 1.55000002e-4 < (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1))) Initial program 91.1%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(if (<= (- 1.0 u1) 0.9980000257492065)
(*
(* 2.0 (* (* (sqrt 2.0) (PI)) u2))
(sqrt (log (sqrt (/ 1.0 (- 1.0 u1))))))
(* (pow (* u1 u1) 0.25) (sin (* (* 2.0 (PI)) u2)))))\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;1 - u1 \leq 0.9980000257492065:\\
\;\;\;\;\left(2 \cdot \left(\left(\sqrt{2} \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\right) \cdot \sqrt{\log \left(\sqrt{\frac{1}{1 - u1}}\right)}\\
\mathbf{else}:\\
\;\;\;\;{\left(u1 \cdot u1\right)}^{0.25} \cdot \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.998000026Initial program 95.4%
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-eval91.9
Applied rewrites91.9%
Taylor expanded in u2 around 0
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-sqrt.f32N/A
lower-PI.f32N/A
lower-sqrt.f32N/A
lower-log.f32N/A
lower-sqrt.f32N/A
lower-/.f32N/A
lower--.f3276.5
Applied rewrites76.5%
if 0.998000026 < (-.f32 #s(literal 1 binary32) u1) Initial program 41.1%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3289.5
Applied rewrites89.5%
lift-sqrt.f32N/A
pow1/2N/A
metadata-evalN/A
pow-prod-upN/A
pow-prod-downN/A
lower-pow.f32N/A
lower-*.f3289.5
Applied rewrites89.5%
Taylor expanded in u1 around 0
unpow2N/A
lower-*.f3289.5
Applied rewrites89.5%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(if (<= (- 1.0 u1) 0.9980000257492065)
(*
(* 2.0 (* (* (sqrt 2.0) (PI)) u2))
(sqrt (log (sqrt (/ 1.0 (- 1.0 u1))))))
(* (sqrt (/ (* (- (- u1)) (- u1)) (- u1))) (sin (* (* 2.0 (PI)) u2)))))\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;1 - u1 \leq 0.9980000257492065:\\
\;\;\;\;\left(2 \cdot \left(\left(\sqrt{2} \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\right) \cdot \sqrt{\log \left(\sqrt{\frac{1}{1 - u1}}\right)}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{\frac{\left(-\left(-u1\right)\right) \cdot \left(-u1\right)}{-u1}} \cdot \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.998000026Initial program 95.4%
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-eval91.9
Applied rewrites91.9%
Taylor expanded in u2 around 0
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-sqrt.f32N/A
lower-PI.f32N/A
lower-sqrt.f32N/A
lower-log.f32N/A
lower-sqrt.f32N/A
lower-/.f32N/A
lower--.f3276.5
Applied rewrites76.5%
if 0.998000026 < (-.f32 #s(literal 1 binary32) u1) Initial program 41.1%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3289.5
Applied rewrites89.5%
+-lft-identityN/A
flip-+N/A
lower-/.f32N/A
metadata-evalN/A
lower--.f32N/A
lower-*.f32N/A
lower--.f3289.5
Applied rewrites89.5%
Final simplification85.5%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(if (<= (- 1.0 u1) 0.9800000190734863)
(*
(sqrt (- (log (- 1.0 u1))))
(* (* (PI) (fma (* (* u2 u2) -1.3333333333333333) (* (PI) (PI)) 2.0)) u2))
(* (sqrt (/ (* (- (- u1)) (- u1)) (- u1))) (sin (* (* 2.0 (PI)) u2)))))\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;1 - u1 \leq 0.9800000190734863:\\
\;\;\;\;\sqrt{-\log \left(1 - u1\right)} \cdot \left(\left(\mathsf{PI}\left(\right) \cdot \mathsf{fma}\left(\left(u2 \cdot u2\right) \cdot -1.3333333333333333, \mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right), 2\right)\right) \cdot u2\right)\\
\mathbf{else}:\\
\;\;\;\;\sqrt{\frac{\left(-\left(-u1\right)\right) \cdot \left(-u1\right)}{-u1}} \cdot \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.980000019Initial program 97.7%
Taylor expanded in u2 around 0
*-commutativeN/A
*-commutativeN/A
associate-*r*N/A
+-commutativeN/A
lower-*.f32N/A
Applied rewrites83.7%
if 0.980000019 < (-.f32 #s(literal 1 binary32) u1) Initial program 46.7%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3285.6
Applied rewrites85.6%
+-lft-identityN/A
flip-+N/A
lower-/.f32N/A
metadata-evalN/A
lower--.f32N/A
lower-*.f32N/A
lower--.f3285.6
Applied rewrites85.6%
Final simplification85.2%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(if (<= (- 1.0 u1) 0.9800000190734863)
(*
(sqrt (- (log (- 1.0 u1))))
(* (* (PI) (fma (* (* u2 u2) -1.3333333333333333) (* (PI) (PI)) 2.0)) u2))
(* (sin (* (* (PI) 2.0) u2)) (sqrt u1))))\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;1 - u1 \leq 0.9800000190734863:\\
\;\;\;\;\sqrt{-\log \left(1 - u1\right)} \cdot \left(\left(\mathsf{PI}\left(\right) \cdot \mathsf{fma}\left(\left(u2 \cdot u2\right) \cdot -1.3333333333333333, \mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right), 2\right)\right) \cdot u2\right)\\
\mathbf{else}:\\
\;\;\;\;\sin \left(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot u2\right) \cdot \sqrt{u1}\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.980000019Initial program 97.7%
Taylor expanded in u2 around 0
*-commutativeN/A
*-commutativeN/A
associate-*r*N/A
+-commutativeN/A
lower-*.f32N/A
Applied rewrites83.7%
if 0.980000019 < (-.f32 #s(literal 1 binary32) u1) Initial program 46.7%
Applied rewrites39.0%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
associate-*r*N/A
*-commutativeN/A
lower-sin.f32N/A
*-commutativeN/A
associate-*r*N/A
*-commutativeN/A
*-commutativeN/A
associate-*r*N/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f32N/A
lower-sqrt.f3285.6
Applied rewrites85.6%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sin (* (* (PI) 2.0) u2)) (sqrt u1)))
\begin{array}{l}
\\
\sin \left(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot u2\right) \cdot \sqrt{u1}
\end{array}
Initial program 57.7%
Applied rewrites32.5%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
associate-*r*N/A
*-commutativeN/A
lower-sin.f32N/A
*-commutativeN/A
associate-*r*N/A
*-commutativeN/A
*-commutativeN/A
associate-*r*N/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f32N/A
lower-sqrt.f3275.8
Applied rewrites75.8%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (* (* (PI) u2) 2.0) (sqrt u1)))
\begin{array}{l}
\\
\left(\left(\mathsf{PI}\left(\right) \cdot u2\right) \cdot 2\right) \cdot \sqrt{u1}
\end{array}
Initial program 57.7%
Applied rewrites32.6%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
associate-*r*N/A
*-commutativeN/A
lower-sin.f32N/A
*-commutativeN/A
associate-*r*N/A
*-commutativeN/A
*-commutativeN/A
associate-*r*N/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f32N/A
lower-sqrt.f3275.8
Applied rewrites75.8%
Taylor expanded in u2 around 0
Applied rewrites65.6%
Final simplification65.6%
herbie shell --seed 2024313
(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))))