
(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 6 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 (if (<= (- 1.0 u1) 0.9998499751091003) (* (sqrt (- (log (- 1.0 u1)))) (sin (* (PI) (+ u2 u2)))) (* (/ 1.0 (/ (sqrt u1) u1)) (sin (* (* 2.0 (PI)) u2)))))
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;1 - u1 \leq 0.9998499751091003:\\
\;\;\;\;\sqrt{-\log \left(1 - u1\right)} \cdot \sin \left(\mathsf{PI}\left(\right) \cdot \left(u2 + u2\right)\right)\\
\mathbf{else}:\\
\;\;\;\;\frac{1}{\frac{\sqrt{u1}}{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) < 0.999849975Initial program 89.8%
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.f3289.5
Applied rewrites89.5%
lift-*.f32N/A
lift-*.f32N/A
associate-*r*N/A
lift-*.f32N/A
associate-*r*N/A
lift-pow.f32N/A
pow-plusN/A
lift-cbrt.f32N/A
metadata-evalN/A
rem-cube-cbrtN/A
*-commutativeN/A
lift-*.f32N/A
*-commutativeN/A
count-2N/A
lift-*.f32N/A
lift-*.f32N/A
distribute-rgt-outN/A
lower-*.f32N/A
lower-+.f3289.8
Applied rewrites89.8%
if 0.999849975 < (-.f32 #s(literal 1 binary32) u1) Initial program 37.5%
Taylor expanded in u1 around 0
*-commutativeN/A
unpow2N/A
rem-square-sqrtN/A
mul-1-negN/A
lower-neg.f32N/A
lower-sqrt.f324.2
Applied rewrites4.2%
Applied rewrites92.9%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (* u2 (PI))))
(if (<= (- 1.0 u1) 0.9998999834060669)
(* (sqrt (- (log (- 1.0 u1)))) (* (* (cos t_0) (sin t_0)) 2.0))
(*
(sqrt
(-
(-
(*
(fma (fma -0.3333333333333333 (* u1 u1) -0.5) (* u1 u1) -1.0)
(* u1 u1))
(log1p u1))))
(sin (* (* 2.0 (PI)) u2))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := u2 \cdot \mathsf{PI}\left(\right)\\
\mathbf{if}\;1 - u1 \leq 0.9998999834060669:\\
\;\;\;\;\sqrt{-\log \left(1 - u1\right)} \cdot \left(\left(\cos t\_0 \cdot \sin t\_0\right) \cdot 2\right)\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-\left(\mathsf{fma}\left(\mathsf{fma}\left(-0.3333333333333333, u1 \cdot u1, -0.5\right), u1 \cdot u1, -1\right) \cdot \left(u1 \cdot u1\right) - \mathsf{log1p}\left(u1\right)\right)} \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) < 0.999899983Initial program 88.9%
lift-sin.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
sin-2N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-cos.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-sin.f32N/A
*-commutativeN/A
lower-*.f3288.9
Applied rewrites88.9%
if 0.999899983 < (-.f32 #s(literal 1 binary32) u1) Initial program 36.4%
Applied rewrites93.5%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
sub-negN/A
*-commutativeN/A
metadata-evalN/A
lower-fma.f32N/A
sub-negN/A
metadata-evalN/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
unpow2N/A
lower-*.f3224.9
Applied rewrites28.7%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(if (<= (- 1.0 u1) 0.9998999834060669)
(* (sqrt (- (log (- 1.0 u1)))) (sin (* (PI) (+ u2 u2))))
(*
(sqrt
(-
(-
(*
(fma (fma -0.3333333333333333 (* u1 u1) -0.5) (* u1 u1) -1.0)
(* u1 u1))
(log1p u1))))
(sin (* (* 2.0 (PI)) u2)))))\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;1 - u1 \leq 0.9998999834060669:\\
\;\;\;\;\sqrt{-\log \left(1 - u1\right)} \cdot \sin \left(\mathsf{PI}\left(\right) \cdot \left(u2 + u2\right)\right)\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-\left(\mathsf{fma}\left(\mathsf{fma}\left(-0.3333333333333333, u1 \cdot u1, -0.5\right), u1 \cdot u1, -1\right) \cdot \left(u1 \cdot u1\right) - \mathsf{log1p}\left(u1\right)\right)} \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) < 0.999899983Initial program 88.9%
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.f3288.6
Applied rewrites88.6%
lift-*.f32N/A
lift-*.f32N/A
associate-*r*N/A
lift-*.f32N/A
associate-*r*N/A
lift-pow.f32N/A
pow-plusN/A
lift-cbrt.f32N/A
metadata-evalN/A
rem-cube-cbrtN/A
*-commutativeN/A
lift-*.f32N/A
*-commutativeN/A
count-2N/A
lift-*.f32N/A
lift-*.f32N/A
distribute-rgt-outN/A
lower-*.f32N/A
lower-+.f3288.9
Applied rewrites88.9%
if 0.999899983 < (-.f32 #s(literal 1 binary32) u1) Initial program 36.4%
Applied rewrites93.5%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
sub-negN/A
*-commutativeN/A
metadata-evalN/A
lower-fma.f32N/A
sub-negN/A
metadata-evalN/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
unpow2N/A
lower-*.f3228.5
Applied rewrites25.6%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (/ 1.0 (/ (sqrt u1) u1)) (sin (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\frac{1}{\frac{\sqrt{u1}}{u1}} \cdot \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
Initial program 58.7%
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%
Applied rewrites76.5%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sin (* (* u2 2.0) (PI))) (sqrt u1)))
\begin{array}{l}
\\
\sin \left(\left(u2 \cdot 2\right) \cdot \mathsf{PI}\left(\right)\right) \cdot \sqrt{u1}
\end{array}
Initial program 58.7%
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%
Applied rewrites76.5%
(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 58.7%
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%
Applied rewrites76.5%
Taylor expanded in u2 around 0
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3268.0
Applied rewrites68.0%
herbie shell --seed 2024322
(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))))