
(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 (sin (* (* 2.0 (PI)) u2)))
(t_1
(*
(- (* (- (* (- (* -0.25 u1) 0.3333333333333333) u1) 0.5) u1) 1.0)
u1)))
(if (<= u1 0.041999999433755875)
(* (pow (* t_1 t_1) 0.25) t_0)
(* (sqrt (- (log (- 1.0 u1)))) t_0))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
t_1 := \left(\left(\left(-0.25 \cdot u1 - 0.3333333333333333\right) \cdot u1 - 0.5\right) \cdot u1 - 1\right) \cdot u1\\
\mathbf{if}\;u1 \leq 0.041999999433755875:\\
\;\;\;\;{\left(t\_1 \cdot t\_1\right)}^{0.25} \cdot t\_0\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-\log \left(1 - u1\right)} \cdot t\_0\\
\end{array}
\end{array}
if u1 < 0.0419999994Initial program 52.5%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
metadata-evalN/A
distribute-lft-neg-inN/A
lower--.f32N/A
distribute-lft-neg-inN/A
metadata-evalN/A
lower-*.f3298.2
Applied rewrites98.2%
lift-sqrt.f32N/A
pow1/2N/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
pow-prod-upN/A
pow-prod-downN/A
lower-pow.f32N/A
lower-*.f32N/A
metadata-eval98.2
Applied rewrites98.2%
lift-*.f32N/A
lift-neg.f32N/A
lift-neg.f32N/A
sqr-negN/A
lower-*.f3298.2
Applied rewrites98.2%
if 0.0419999994 < u1 Initial program 97.8%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (log (- 1.0 u1))))
(if (<= t_0 -0.03500000014901161)
(* (sqrt (- t_0)) (* (* (PI) u2) 2.0))
(*
(sqrt (- (* (- (* (- (* -0.3333333333333333 u1) 0.5) u1) 1.0) u1)))
(sin (* (* 2.0 (PI)) u2))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \log \left(1 - u1\right)\\
\mathbf{if}\;t\_0 \leq -0.03500000014901161:\\
\;\;\;\;\sqrt{-t\_0} \cdot \left(\left(\mathsf{PI}\left(\right) \cdot u2\right) \cdot 2\right)\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-\left(\left(-0.3333333333333333 \cdot u1 - 0.5\right) \cdot u1 - 1\right) \cdot u1} \cdot \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\end{array}
\end{array}
if (log.f32 (-.f32 #s(literal 1 binary32) u1)) < -0.0350000001Initial program 97.5%
lift-neg.f32N/A
lift-log.f32N/A
neg-logN/A
lower-log.f32N/A
lower-/.f3296.9
Applied rewrites96.9%
Taylor expanded in u2 around 0
count-2-revN/A
distribute-rgt-outN/A
count-2-revN/A
lower-*.f32N/A
lower-sqrt.f32N/A
log-recN/A
lower-neg.f32N/A
lower-log.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3284.6
Applied rewrites84.6%
if -0.0350000001 < (log.f32 (-.f32 #s(literal 1 binary32) u1)) Initial program 52.2%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
metadata-evalN/A
distribute-lft-neg-inN/A
*-commutativeN/A
distribute-lft-neg-inN/A
lower--.f32N/A
distribute-lft-neg-inN/A
*-commutativeN/A
distribute-lft-neg-inN/A
metadata-evalN/A
lower-*.f3297.1
Applied rewrites97.1%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (log (- 1.0 u1))))
(if (<= t_0 -0.021199999377131462)
(* (sqrt (- t_0)) (* (* (PI) u2) 2.0))
(* (sqrt (- (* (- (* -0.5 u1) 1.0) u1))) (sin (* (* 2.0 (PI)) u2))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \log \left(1 - u1\right)\\
\mathbf{if}\;t\_0 \leq -0.021199999377131462:\\
\;\;\;\;\sqrt{-t\_0} \cdot \left(\left(\mathsf{PI}\left(\right) \cdot u2\right) \cdot 2\right)\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-\left(-0.5 \cdot u1 - 1\right) \cdot u1} \cdot \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\end{array}
\end{array}
if (log.f32 (-.f32 #s(literal 1 binary32) u1)) < -0.0211999994Initial program 96.8%
lift-neg.f32N/A
lift-log.f32N/A
neg-logN/A
lower-log.f32N/A
lower-/.f3296.1
Applied rewrites96.1%
Taylor expanded in u2 around 0
count-2-revN/A
distribute-rgt-outN/A
count-2-revN/A
lower-*.f32N/A
lower-sqrt.f32N/A
log-recN/A
lower-neg.f32N/A
lower-log.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3283.3
Applied rewrites83.3%
if -0.0211999994 < (log.f32 (-.f32 #s(literal 1 binary32) u1)) Initial program 49.6%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
metadata-evalN/A
distribute-lft-neg-inN/A
*-commutativeN/A
distribute-lft-neg-inN/A
lower--.f32N/A
distribute-lft-neg-inN/A
*-commutativeN/A
distribute-lft-neg-inN/A
metadata-evalN/A
lower-*.f3296.0
Applied rewrites96.0%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (log (- 1.0 u1))) (t_1 (* (* (PI) u2) 2.0)))
(if (<= t_0 -0.0005600000149570405)
(* (sqrt (- t_0)) t_1)
(* (sin t_1) (sqrt u1)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \log \left(1 - u1\right)\\
t_1 := \left(\mathsf{PI}\left(\right) \cdot u2\right) \cdot 2\\
\mathbf{if}\;t\_0 \leq -0.0005600000149570405:\\
\;\;\;\;\sqrt{-t\_0} \cdot t\_1\\
\mathbf{else}:\\
\;\;\;\;\sin t\_1 \cdot \sqrt{u1}\\
\end{array}
\end{array}
if (log.f32 (-.f32 #s(literal 1 binary32) u1)) < -5.60000015e-4Initial program 92.6%
lift-neg.f32N/A
lift-log.f32N/A
neg-logN/A
lower-log.f32N/A
lower-/.f3290.8
Applied rewrites90.8%
Taylor expanded in u2 around 0
count-2-revN/A
distribute-rgt-outN/A
count-2-revN/A
lower-*.f32N/A
lower-sqrt.f32N/A
log-recN/A
lower-neg.f32N/A
lower-log.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3279.4
Applied rewrites79.4%
if -5.60000015e-4 < (log.f32 (-.f32 #s(literal 1 binary32) u1)) Initial program 41.9%
lift-neg.f32N/A
lift-log.f32N/A
neg-logN/A
lower-log.f32N/A
lower-/.f3239.6
Applied rewrites39.6%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower-sin.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f32N/A
lower-sqrt.f3289.4
Applied rewrites89.4%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (sin (* (* 2.0 (PI)) u2))))
(if (<= u1 0.041999999433755875)
(*
(sqrt
(-
(*
(- (* (- (* (- (* -0.25 u1) 0.3333333333333333) u1) 0.5) u1) 1.0)
u1)))
t_0)
(* (sqrt (- (log (- 1.0 u1)))) t_0))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\mathbf{if}\;u1 \leq 0.041999999433755875:\\
\;\;\;\;\sqrt{-\left(\left(\left(-0.25 \cdot u1 - 0.3333333333333333\right) \cdot u1 - 0.5\right) \cdot u1 - 1\right) \cdot u1} \cdot t\_0\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-\log \left(1 - u1\right)} \cdot t\_0\\
\end{array}
\end{array}
if u1 < 0.0419999994Initial program 52.5%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
metadata-evalN/A
distribute-lft-neg-inN/A
lower--.f32N/A
distribute-lft-neg-inN/A
metadata-evalN/A
lower-*.f3298.2
Applied rewrites98.2%
if 0.0419999994 < u1 Initial program 97.8%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(*
(sqrt
(-
(* (- (* (- (* (- (* -0.25 u1) 0.3333333333333333) u1) 0.5) u1) 1.0) u1)))
(sin (* (* 2.0 (PI)) u2))))\begin{array}{l}
\\
\sqrt{-\left(\left(\left(-0.25 \cdot u1 - 0.3333333333333333\right) \cdot u1 - 0.5\right) \cdot u1 - 1\right) \cdot u1} \cdot \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
Initial program 60.3%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
metadata-evalN/A
distribute-lft-neg-inN/A
lower--.f32N/A
distribute-lft-neg-inN/A
metadata-evalN/A
lower-*.f3293.0
Applied rewrites93.0%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sin (* (* (PI) u2) 2.0)) (sqrt u1)))
\begin{array}{l}
\\
\sin \left(\left(\mathsf{PI}\left(\right) \cdot u2\right) \cdot 2\right) \cdot \sqrt{u1}
\end{array}
Initial program 60.3%
lift-neg.f32N/A
lift-log.f32N/A
neg-logN/A
lower-log.f32N/A
lower-/.f3258.2
Applied rewrites58.2%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower-sin.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f32N/A
lower-sqrt.f3274.5
Applied rewrites74.5%
(FPCore (cosTheta_i u1 u2) :precision binary32 0.0)
float code(float cosTheta_i, float u1, float u2) {
return 0.0f;
}
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 = 0.0e0
end function
function code(cosTheta_i, u1, u2) return Float32(0.0) end
function tmp = code(cosTheta_i, u1, u2) tmp = single(0.0); end
\begin{array}{l}
\\
0
\end{array}
Initial program 60.3%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
metadata-evalN/A
distribute-lft-neg-inN/A
lower--.f32N/A
distribute-lft-neg-inN/A
metadata-evalN/A
lower-*.f3293.0
Applied rewrites93.0%
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%
lift-*.f32N/A
*-commutativeN/A
lower-*.f324.0
Applied rewrites4.6%
lift-*.f32N/A
*-commutativeN/A
lift-sin.f32N/A
lift-*.f32N/A
*-commutativeN/A
count-2-revN/A
lift-PI.f32N/A
sin-+PIN/A
lift-PI.f32N/A
sin-PIN/A
metadata-evalN/A
sin-PIN/A
lift-PI.f32N/A
lower-*.f32N/A
lift-PI.f32N/A
sin-PI7.1
Applied rewrites7.1%
Final simplification7.1%
herbie shell --seed 2024340
(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))))