
(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 9 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 0.03999999910593033)
(* (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 0.03999999910593033:\\
\;\;\;\;{\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 < 0.0399999991Initial program 49.9%
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-*.f3298.3
Applied rewrites98.3%
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-eval98.3
Applied rewrites98.3%
lift-*.f32N/A
lift-neg.f32N/A
lift-neg.f32N/A
sqr-negN/A
lower-*.f3298.3
Applied rewrites98.3%
if 0.0399999991 < u1 Initial program 97.2%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (log (- 1.0 u1))) (t_1 (sin (* (* 2.0 (PI)) u2))))
(if (<= t_0 -0.03999999910593033)
(* (sqrt (- t_0)) t_1)
(*
(sqrt
(-
(*
(- (* (- (* (- (* -0.25 u1) 0.3333333333333333) u1) 0.5) u1) 1.0)
u1)))
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 -0.03999999910593033:\\
\;\;\;\;\sqrt{-t\_0} \cdot t\_1\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-\left(\left(\left(-0.25 \cdot u1 - 0.3333333333333333\right) \cdot u1 - 0.5\right) \cdot u1 - 1\right) \cdot u1} \cdot t\_1\\
\end{array}
\end{array}
if (log.f32 (-.f32 #s(literal 1 binary32) u1)) < -0.0399999991Initial program 97.2%
if -0.0399999991 < (log.f32 (-.f32 #s(literal 1 binary32) u1)) Initial program 49.9%
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-*.f3298.3
Applied rewrites98.3%
(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 55.4%
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-*.f3294.6
Applied rewrites94.6%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (* (- (* (- (* -0.3333333333333333 u1) 0.5) u1) 1.0) u1))) (sin (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\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}
Initial program 55.4%
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-*.f3292.9
Applied rewrites92.9%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (+ (* (* 0.5 u1) u1) u1)) (sin (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\sqrt{\left(0.5 \cdot u1\right) \cdot u1 + u1} \cdot \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
Initial program 55.4%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
+-commutativeN/A
lower-fma.f3236.9
Applied rewrites36.6%
Applied rewrites89.2%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (* (- 1.0 (* -0.5 u1)) u1)) (sin (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\sqrt{\left(1 - -0.5 \cdot u1\right) \cdot u1} \cdot \sin \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
Initial program 55.4%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
+-commutativeN/A
lower-fma.f3236.1
Applied rewrites37.6%
Applied rewrites89.2%
(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 55.4%
lift-sqrt.f32N/A
pow1/2N/A
pow-to-expN/A
lower-exp.f32N/A
*-commutativeN/A
log-pow-revN/A
pow1/2N/A
lift-sqrt.f32N/A
lower-log.f3255.4
lift-log.f32N/A
lift--.f32N/A
*-lft-identityN/A
fp-cancel-sub-sign-invN/A
distribute-lft-neg-inN/A
*-lft-identityN/A
lower-log1p.f32N/A
lower-neg.f3228.6
Applied rewrites29.1%
Applied rewrites17.4%
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.f3278.2
Applied rewrites78.2%
(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 55.4%
lift-sqrt.f32N/A
pow1/2N/A
pow-to-expN/A
lower-exp.f32N/A
*-commutativeN/A
log-pow-revN/A
pow1/2N/A
lift-sqrt.f32N/A
lower-log.f3255.4
lift-log.f32N/A
lift--.f32N/A
*-lft-identityN/A
fp-cancel-sub-sign-invN/A
distribute-lft-neg-inN/A
*-lft-identityN/A
lower-log1p.f32N/A
lower-neg.f3228.8
Applied rewrites28.7%
Applied rewrites19.2%
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.f3278.2
Applied rewrites78.2%
Taylor expanded in u2 around 0
Applied rewrites68.6%
(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 55.4%
lift-sqrt.f32N/A
pow1/2N/A
pow-to-expN/A
lower-exp.f32N/A
*-commutativeN/A
log-pow-revN/A
pow1/2N/A
lift-sqrt.f32N/A
lower-log.f3255.4
lift-log.f32N/A
lift--.f32N/A
*-lft-identityN/A
fp-cancel-sub-sign-invN/A
distribute-lft-neg-inN/A
*-lft-identityN/A
lower-log1p.f32N/A
lower-neg.f3229.1
Applied rewrites28.0%
Applied rewrites17.5%
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.f3278.2
Applied rewrites78.2%
Applied rewrites7.2%
Final simplification7.2%
herbie shell --seed 2024332
(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))))