
(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 7 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 (- (log (- 1.0 u1)))) (t_1 (cbrt (PI))))
(if (<= t_0 0.00013080000644549727)
(* (cos (* (* 2.0 (PI)) u2)) (sqrt u1))
(* (cos (* (* (* t_1 u2) 2.0) (pow t_1 2.0))) (sqrt t_0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := -\log \left(1 - u1\right)\\
t_1 := \sqrt[3]{\mathsf{PI}\left(\right)}\\
\mathbf{if}\;t\_0 \leq 0.00013080000644549727:\\
\;\;\;\;\cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right) \cdot \sqrt{u1}\\
\mathbf{else}:\\
\;\;\;\;\cos \left(\left(\left(t\_1 \cdot u2\right) \cdot 2\right) \cdot {t\_1}^{2}\right) \cdot \sqrt{t\_0}\\
\end{array}
\end{array}
if (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1))) < 1.30800006e-4Initial program 39.7%
Taylor expanded in u1 around 0
*-commutativeN/A
unpow2N/A
rem-square-sqrtN/A
mul-1-negN/A
lower-neg.f32N/A
lower-sqrt.f323.6
Applied rewrites3.6%
Applied rewrites91.9%
if 1.30800006e-4 < (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1))) Initial program 89.3%
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.f3289.4
Applied rewrites89.4%
Final simplification90.9%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (- (log (- 1.0 u1)))))
(if (<= t_0 0.00013080000644549727)
(* (cos (* (* 2.0 (PI)) u2)) (sqrt u1))
(*
(cos
(*
(* (* (* (sqrt (PI)) u2) 2.0) (pow (PI) 0.16666666666666666))
(cbrt (PI))))
(sqrt t_0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := -\log \left(1 - u1\right)\\
\mathbf{if}\;t\_0 \leq 0.00013080000644549727:\\
\;\;\;\;\cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right) \cdot \sqrt{u1}\\
\mathbf{else}:\\
\;\;\;\;\cos \left(\left(\left(\left(\sqrt{\mathsf{PI}\left(\right)} \cdot u2\right) \cdot 2\right) \cdot {\mathsf{PI}\left(\right)}^{0.16666666666666666}\right) \cdot \sqrt[3]{\mathsf{PI}\left(\right)}\right) \cdot \sqrt{t\_0}\\
\end{array}
\end{array}
if (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1))) < 1.30800006e-4Initial program 39.7%
Taylor expanded in u1 around 0
*-commutativeN/A
unpow2N/A
rem-square-sqrtN/A
mul-1-negN/A
lower-neg.f32N/A
lower-sqrt.f323.6
Applied rewrites3.6%
Applied rewrites91.9%
if 1.30800006e-4 < (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1))) Initial program 89.3%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
lift-PI.f32N/A
add-sqr-sqrtN/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
lower-*.f32N/A
lift-PI.f32N/A
lower-sqrt.f32N/A
lift-PI.f32N/A
lower-sqrt.f3289.2
Applied rewrites89.2%
lift-*.f32N/A
*-commutativeN/A
lift-sqrt.f32N/A
pow1/2N/A
metadata-evalN/A
metadata-evalN/A
pow-prod-upN/A
pow1/3N/A
lift-cbrt.f32N/A
sqrt-pow2N/A
lift-sqrt.f32N/A
associate-*l*N/A
lower-*.f32N/A
lower-*.f32N/A
lift-sqrt.f32N/A
sqrt-pow2N/A
lower-pow.f32N/A
metadata-eval89.3
lift-*.f32N/A
*-commutativeN/A
Applied rewrites89.3%
Final simplification90.8%
(FPCore (cosTheta_i u1 u2) :precision binary32 (let* ((t_0 (- (log (- 1.0 u1)))) (t_1 (cos (* (* 2.0 (PI)) u2)))) (if (<= t_0 0.00013080000644549727) (* t_1 (sqrt u1)) (* t_1 (sqrt t_0)))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := -\log \left(1 - u1\right)\\
t_1 := \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\mathbf{if}\;t\_0 \leq 0.00013080000644549727:\\
\;\;\;\;t\_1 \cdot \sqrt{u1}\\
\mathbf{else}:\\
\;\;\;\;t\_1 \cdot \sqrt{t\_0}\\
\end{array}
\end{array}
if (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1))) < 1.30800006e-4Initial program 39.7%
Taylor expanded in u1 around 0
*-commutativeN/A
unpow2N/A
rem-square-sqrtN/A
mul-1-negN/A
lower-neg.f32N/A
lower-sqrt.f323.6
Applied rewrites3.6%
Applied rewrites91.9%
if 1.30800006e-4 < (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1))) Initial program 89.3%
Final simplification90.8%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (+ (sqrt u1) (* (* (* 0.16666666666666666 (sqrt u1)) u1) u1)) (cos (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\left(\sqrt{u1} + \left(\left(0.16666666666666666 \cdot \sqrt{u1}\right) \cdot u1\right) \cdot u1\right) \cdot \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
Initial program 59.8%
Applied rewrites43.9%
Taylor expanded in u1 around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
*-commutativeN/A
lower-fma.f32N/A
lower-sqrt.f32N/A
lower-/.f32N/A
lower-*.f32N/A
lower-sqrt.f32N/A
unpow2N/A
lower-*.f32N/A
lower-sqrt.f3275.9
Applied rewrites75.9%
Applied rewrites75.7%
Taylor expanded in u1 around 0
Applied rewrites76.0%
Final simplification76.0%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (cos (* (* 2.0 (PI)) u2)) (sqrt u1)))
\begin{array}{l}
\\
\cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right) \cdot \sqrt{u1}
\end{array}
Initial program 59.8%
Taylor expanded in u1 around 0
*-commutativeN/A
unpow2N/A
rem-square-sqrtN/A
mul-1-negN/A
lower-neg.f32N/A
lower-sqrt.f323.5
Applied rewrites3.5%
Applied rewrites75.9%
Final simplification75.9%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* 1.0 (sqrt (- (- u1)))))
float code(float cosTheta_i, float u1, float u2) {
return 1.0f * sqrtf(-(-u1));
}
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 = 1.0e0 * sqrt(-(-u1))
end function
function code(cosTheta_i, u1, u2) return Float32(Float32(1.0) * sqrt(Float32(-Float32(-u1)))) end
function tmp = code(cosTheta_i, u1, u2) tmp = single(1.0) * sqrt(-(-u1)); end
\begin{array}{l}
\\
1 \cdot \sqrt{-\left(-u1\right)}
\end{array}
Initial program 59.8%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3275.9
Applied rewrites75.9%
Taylor expanded in u2 around 0
Applied rewrites62.6%
Final simplification62.6%
(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(Float32(-sqrt(u1)) * Float32(1.0)) end
function tmp = code(cosTheta_i, u1, u2) tmp = -sqrt(u1) * single(1.0); end
\begin{array}{l}
\\
\left(-\sqrt{u1}\right) \cdot 1
\end{array}
Initial program 59.8%
Taylor expanded in u1 around 0
*-commutativeN/A
unpow2N/A
rem-square-sqrtN/A
mul-1-negN/A
lower-neg.f32N/A
lower-sqrt.f323.5
Applied rewrites3.5%
Taylor expanded in u2 around 0
Applied rewrites5.7%
herbie shell --seed 2024285
(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))))