
(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
(if (<= (- 1.0 u1) 0.9968500137329102)
(*
(cos
(*
(sqrt (PI))
(* (pow (PI) 0.16666666666666666) (* 2.0 (* u2 (cbrt (PI)))))))
(sqrt (- (log (- 1.0 u1)))))
(* (cos (* (* 2.0 (PI)) u2)) (sqrt (+ (* (* 0.5 u1) u1) u1)))))\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;1 - u1 \leq 0.9968500137329102:\\
\;\;\;\;\cos \left(\sqrt{\mathsf{PI}\left(\right)} \cdot \left({\mathsf{PI}\left(\right)}^{0.16666666666666666} \cdot \left(2 \cdot \left(u2 \cdot \sqrt[3]{\mathsf{PI}\left(\right)}\right)\right)\right)\right) \cdot \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{else}:\\
\;\;\;\;\cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right) \cdot \sqrt{\left(0.5 \cdot u1\right) \cdot u1 + u1}\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.99685001Initial program 94.8%
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.f3294.9
Applied rewrites94.9%
lift-*.f32N/A
unpow1N/A
metadata-evalN/A
pow-powN/A
pow3N/A
unpow-prod-downN/A
lift-sqrt.f32N/A
lift-sqrt.f32N/A
rem-square-sqrtN/A
pow1/3N/A
lift-cbrt.f32N/A
associate-*r*N/A
lower-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
associate-*r*N/A
lower-*.f32N/A
lower-*.f32N/A
Applied rewrites95.1%
if 0.99685001 < (-.f32 #s(literal 1 binary32) u1) Initial program 47.0%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3287.0
Applied rewrites87.0%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
+-commutativeN/A
lower-fma.f3262.1
Applied rewrites61.7%
Applied rewrites98.5%
Final simplification97.6%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (sqrt (PI))))
(if (<= (- 1.0 u1) 0.9968500137329102)
(* (cos (* (* (* 2.0 u2) t_0) t_0)) (sqrt (- (log (- 1.0 u1)))))
(* (cos (* (* 2.0 (PI)) u2)) (sqrt (+ (* (* 0.5 u1) u1) u1))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{\mathsf{PI}\left(\right)}\\
\mathbf{if}\;1 - u1 \leq 0.9968500137329102:\\
\;\;\;\;\cos \left(\left(\left(2 \cdot u2\right) \cdot t\_0\right) \cdot t\_0\right) \cdot \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{else}:\\
\;\;\;\;\cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right) \cdot \sqrt{\left(0.5 \cdot u1\right) \cdot u1 + u1}\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.99685001Initial program 94.8%
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.f3294.9
Applied rewrites94.9%
if 0.99685001 < (-.f32 #s(literal 1 binary32) u1) Initial program 47.0%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3287.0
Applied rewrites87.0%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
+-commutativeN/A
lower-fma.f3262.7
Applied rewrites61.7%
Applied rewrites98.5%
Final simplification97.6%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (cos (* (* 2.0 (PI)) u2))))
(if (<= (- 1.0 u1) 0.9968500137329102)
(* t_0 (sqrt (- (log (- 1.0 u1)))))
(* t_0 (sqrt (+ (* (* 0.5 u1) u1) u1))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)\\
\mathbf{if}\;1 - u1 \leq 0.9968500137329102:\\
\;\;\;\;t\_0 \cdot \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{else}:\\
\;\;\;\;t\_0 \cdot \sqrt{\left(0.5 \cdot u1\right) \cdot u1 + u1}\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.99685001Initial program 94.8%
if 0.99685001 < (-.f32 #s(literal 1 binary32) u1) Initial program 47.0%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3287.0
Applied rewrites87.0%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
+-commutativeN/A
lower-fma.f3261.3
Applied rewrites62.8%
Applied rewrites98.5%
Final simplification97.5%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (cos (* (* 2.0 (PI)) u2)) (sqrt (+ (* (* 0.5 u1) u1) u1))))
\begin{array}{l}
\\
\cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right) \cdot \sqrt{\left(0.5 \cdot u1\right) \cdot u1 + u1}
\end{array}
Initial program 59.3%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3276.1
Applied rewrites76.1%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
+-commutativeN/A
lower-fma.f3254.6
Applied rewrites53.6%
Applied rewrites88.3%
Final simplification88.3%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (* (+ (* 0.5 u1) 1.0) u1)) (cos (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\sqrt{\left(0.5 \cdot u1 + 1\right) \cdot u1} \cdot \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
Initial program 59.3%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3276.1
Applied rewrites76.1%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
+-commutativeN/A
lower-fma.f3255.0
Applied rewrites54.2%
Applied rewrites88.1%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt u1) (cos (* (* 2.0 u2) (PI)))))
\begin{array}{l}
\\
\sqrt{u1} \cdot \cos \left(\left(2 \cdot u2\right) \cdot \mathsf{PI}\left(\right)\right)
\end{array}
Initial program 59.3%
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 rewrites76.1%
Final simplification76.1%
(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 59.3%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3276.1
Applied rewrites76.1%
Taylor expanded in u2 around 0
Applied rewrites64.3%
Final simplification64.3%
(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(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 59.3%
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 rewrites4.3%
herbie shell --seed 2024331
(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))))