
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log (- 1.0 u1)))) (cos (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \cos \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)))) (cos (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (cos (* (* 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 := \cos \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 53.2%
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-*.f3298.7
Applied rewrites98.7%
if 0.0419999994 < u1 Initial program 97.8%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (sqrt (- (log (- 1.0 u1))))) (t_1 (cos (* (* 2.0 (PI)) u2))))
(if (<= (* t_0 t_1) 0.1420000046491623)
(*
(sqrt (- (* (- (* (- (* -0.3333333333333333 u1) 0.5) u1) 1.0) u1)))
t_1)
(* t_0 1.0))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{-\log \left(1 - u1\right)}\\
t_1 := \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\mathbf{if}\;t\_0 \cdot t\_1 \leq 0.1420000046491623:\\
\;\;\;\;\sqrt{-\left(\left(-0.3333333333333333 \cdot u1 - 0.5\right) \cdot u1 - 1\right) \cdot u1} \cdot t\_1\\
\mathbf{else}:\\
\;\;\;\;t\_0 \cdot 1\\
\end{array}
\end{array}
if (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) < 0.142000005Initial program 51.7%
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-*.f3298.0
Applied rewrites98.0%
if 0.142000005 < (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) Initial program 97.3%
Taylor expanded in u2 around 0
Applied rewrites86.9%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (sqrt (- (log (- 1.0 u1))))) (t_1 (cos (* (* 2.0 (PI)) u2))))
(if (<= (* t_0 t_1) 0.10260000079870224)
(* (sqrt (- (* (- (* -0.5 u1) 1.0) u1))) t_1)
(* t_0 1.0))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{-\log \left(1 - u1\right)}\\
t_1 := \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\mathbf{if}\;t\_0 \cdot t\_1 \leq 0.10260000079870224:\\
\;\;\;\;\sqrt{-\left(-0.5 \cdot u1 - 1\right) \cdot u1} \cdot t\_1\\
\mathbf{else}:\\
\;\;\;\;t\_0 \cdot 1\\
\end{array}
\end{array}
if (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) < 0.102600001Initial program 49.5%
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-*.f3295.9
Applied rewrites95.9%
if 0.102600001 < (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) Initial program 96.0%
Taylor expanded in u2 around 0
Applied rewrites84.9%
(FPCore (cosTheta_i u1 u2) :precision binary32 (let* ((t_0 (sqrt (- (log (- 1.0 u1))))) (t_1 (cos (* (* 2.0 (PI)) u2)))) (if (<= (* t_0 t_1) 0.024000000208616257) (* (sqrt u1) t_1) (* t_0 1.0))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{-\log \left(1 - u1\right)}\\
t_1 := \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\mathbf{if}\;t\_0 \cdot t\_1 \leq 0.024000000208616257:\\
\;\;\;\;\sqrt{u1} \cdot t\_1\\
\mathbf{else}:\\
\;\;\;\;t\_0 \cdot 1\\
\end{array}
\end{array}
if (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) < 0.0240000002Initial program 41.5%
lift-log.f32N/A
lift--.f32N/A
flip--N/A
log-divN/A
lower--.f32N/A
metadata-evalN/A
fp-cancel-sub-sign-invN/A
lower-log1p.f32N/A
lower-*.f32N/A
lower-neg.f32N/A
lower-log1p.f3251.9
Applied rewrites53.5%
Taylor expanded in u1 around 0
lower-sqrt.f3289.8
Applied rewrites89.8%
if 0.0240000002 < (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) Initial program 91.2%
Taylor expanded in u2 around 0
Applied rewrites81.1%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (sqrt (- (log (- 1.0 u1))))))
(if (<= (* t_0 (cos (* (* 2.0 (PI)) u2))) 0.014000000432133675)
(* (sqrt u1) 1.0)
(* t_0 1.0))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{if}\;t\_0 \cdot \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right) \leq 0.014000000432133675:\\
\;\;\;\;\sqrt{u1} \cdot 1\\
\mathbf{else}:\\
\;\;\;\;t\_0 \cdot 1\\
\end{array}
\end{array}
if (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) < 0.0140000004Initial program 39.6%
lift-log.f32N/A
lift--.f32N/A
flip--N/A
log-divN/A
lower--.f32N/A
metadata-evalN/A
fp-cancel-sub-sign-invN/A
lower-log1p.f32N/A
lower-*.f32N/A
lower-neg.f32N/A
lower-log1p.f3255.6
Applied rewrites55.7%
Taylor expanded in u1 around 0
lower-sqrt.f3291.0
Applied rewrites91.0%
Taylor expanded in u2 around 0
Applied rewrites74.3%
if 0.0140000004 < (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) Initial program 89.8%
Taylor expanded in u2 around 0
Applied rewrites79.3%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(*
(sqrt
(-
(* (- (* (- (* (- (* -0.25 u1) 0.3333333333333333) u1) 0.5) u1) 1.0) u1)))
(cos (* (* 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 \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
Initial program 58.4%
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 (* (pow u1 0.5) 1.0))
float code(float cosTheta_i, float u1, float u2) {
return powf(u1, 0.5f) * 1.0f;
}
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 = (u1 ** 0.5e0) * 1.0e0
end function
function code(cosTheta_i, u1, u2) return Float32((u1 ^ Float32(0.5)) * Float32(1.0)) end
function tmp = code(cosTheta_i, u1, u2) tmp = (u1 ^ single(0.5)) * single(1.0); end
\begin{array}{l}
\\
{u1}^{0.5} \cdot 1
\end{array}
Initial program 58.4%
lift-log.f32N/A
lift--.f32N/A
flip--N/A
log-divN/A
lower--.f32N/A
metadata-evalN/A
fp-cancel-sub-sign-invN/A
lower-log1p.f32N/A
lower-*.f32N/A
lower-neg.f32N/A
lower-log1p.f3247.3
Applied rewrites47.3%
Taylor expanded in u1 around 0
lower-sqrt.f3276.4
Applied rewrites76.4%
Taylor expanded in u2 around 0
Applied rewrites65.3%
Applied rewrites65.3%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt u1) 1.0))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(u1) * 1.0f;
}
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 = sqrt(u1) * 1.0e0
end function
function code(cosTheta_i, u1, u2) return Float32(sqrt(u1) * Float32(1.0)) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(u1) * single(1.0); end
\begin{array}{l}
\\
\sqrt{u1} \cdot 1
\end{array}
Initial program 58.4%
lift-log.f32N/A
lift--.f32N/A
flip--N/A
log-divN/A
lower--.f32N/A
metadata-evalN/A
fp-cancel-sub-sign-invN/A
lower-log1p.f32N/A
lower-*.f32N/A
lower-neg.f32N/A
lower-log1p.f3247.4
Applied rewrites48.3%
Taylor expanded in u1 around 0
lower-sqrt.f3276.4
Applied rewrites76.4%
Taylor expanded in u2 around 0
Applied rewrites65.3%
herbie shell --seed 2024343
(FPCore (cosTheta_i u1 u2)
:name "Beckmann Sample, near normal, slope_x"
: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)))) (cos (* (* 2.0 (PI)) u2))))