
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(+ 1.0 c)
(*
(* (/ 1.0 (sqrt (PI))) (/ (sqrt (- (- 1.0 cosTheta) cosTheta)) cosTheta))
(exp (* (- cosTheta) cosTheta))))))\begin{array}{l}
\\
\frac{1}{\left(1 + c\right) + \left(\frac{1}{\sqrt{\mathsf{PI}\left(\right)}} \cdot \frac{\sqrt{\left(1 - cosTheta\right) - cosTheta}}{cosTheta}\right) \cdot e^{\left(-cosTheta\right) \cdot cosTheta}}
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 9 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(+ 1.0 c)
(*
(* (/ 1.0 (sqrt (PI))) (/ (sqrt (- (- 1.0 cosTheta) cosTheta)) cosTheta))
(exp (* (- cosTheta) cosTheta))))))\begin{array}{l}
\\
\frac{1}{\left(1 + c\right) + \left(\frac{1}{\sqrt{\mathsf{PI}\left(\right)}} \cdot \frac{\sqrt{\left(1 - cosTheta\right) - cosTheta}}{cosTheta}\right) \cdot e^{\left(-cosTheta\right) \cdot cosTheta}}
\end{array}
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(*
(exp (* (- cosTheta) cosTheta))
(/
(* (sqrt (- (- 1.0 cosTheta) cosTheta)) (pow (PI) -0.16666666666666666))
(* (cbrt (PI)) cosTheta)))
(+ c 1.0))))\begin{array}{l}
\\
\frac{1}{e^{\left(-cosTheta\right) \cdot cosTheta} \cdot \frac{\sqrt{\left(1 - cosTheta\right) - cosTheta} \cdot {\mathsf{PI}\left(\right)}^{-0.16666666666666666}}{\sqrt[3]{\mathsf{PI}\left(\right)} \cdot cosTheta} + \left(c + 1\right)}
\end{array}
Initial program 98.0%
lift-*.f32N/A
lift-/.f32N/A
associate-*l/N/A
*-commutativeN/A
lift-sqrt.f32N/A
pow1/2N/A
lift-PI.f32N/A
add-cube-cbrtN/A
unpow-prod-downN/A
pow2N/A
pow-powN/A
metadata-evalN/A
unpow1N/A
times-fracN/A
lower-*.f32N/A
Applied rewrites98.7%
lift-*.f32N/A
*-commutativeN/A
lift-/.f32N/A
lift-/.f32N/A
associate-/l/N/A
associate-*r/N/A
lower-/.f32N/A
lower-*.f32N/A
lift-/.f32N/A
lift-pow.f32N/A
pow-flipN/A
lower-pow.f32N/A
metadata-evalN/A
lower-*.f3298.8
Applied rewrites98.8%
Final simplification98.8%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(*
(/ (sqrt (- (- 1.0 cosTheta) cosTheta)) (* (sqrt (PI)) cosTheta))
(exp (* (- cosTheta) cosTheta)))
(+ c 1.0))))\begin{array}{l}
\\
\frac{1}{\frac{\sqrt{\left(1 - cosTheta\right) - cosTheta}}{\sqrt{\mathsf{PI}\left(\right)} \cdot cosTheta} \cdot e^{\left(-cosTheta\right) \cdot cosTheta} + \left(c + 1\right)}
\end{array}
Initial program 98.0%
lift-*.f32N/A
lift-/.f32N/A
lift-/.f32N/A
frac-timesN/A
*-lft-identityN/A
lower-/.f32N/A
*-commutativeN/A
lower-*.f3298.7
Applied rewrites98.7%
Final simplification98.7%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(*
(/ (sqrt (- (- 1.0 cosTheta) cosTheta)) (* (sqrt (PI)) cosTheta))
(exp (* (- cosTheta) cosTheta)))
1.0)))\begin{array}{l}
\\
\frac{1}{\frac{\sqrt{\left(1 - cosTheta\right) - cosTheta}}{\sqrt{\mathsf{PI}\left(\right)} \cdot cosTheta} \cdot e^{\left(-cosTheta\right) \cdot cosTheta} + 1}
\end{array}
Initial program 98.0%
lift-*.f32N/A
lift-/.f32N/A
associate-*l/N/A
*-commutativeN/A
lift-sqrt.f32N/A
pow1/2N/A
lift-PI.f32N/A
add-cube-cbrtN/A
unpow-prod-downN/A
pow2N/A
pow-powN/A
metadata-evalN/A
unpow1N/A
times-fracN/A
lower-*.f32N/A
Applied rewrites98.7%
lift-*.f32N/A
*-commutativeN/A
lift-/.f32N/A
lift-/.f32N/A
frac-timesN/A
lift-pow.f32N/A
lift-cbrt.f32N/A
pow1/3N/A
pow-prod-upN/A
metadata-evalN/A
pow1/2N/A
lift-sqrt.f32N/A
associate-*l/N/A
lift-/.f32N/A
frac-timesN/A
*-lft-identityN/A
lower-/.f32N/A
Applied rewrites98.7%
Taylor expanded in c around 0
Applied rewrites98.6%
Final simplification98.6%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(*
(/ (sqrt (/ (- (- 1.0 cosTheta) cosTheta) (PI))) cosTheta)
(exp (* (- cosTheta) cosTheta)))
(+ c 1.0))))\begin{array}{l}
\\
\frac{1}{\frac{\sqrt{\frac{\left(1 - cosTheta\right) - cosTheta}{\mathsf{PI}\left(\right)}}}{cosTheta} \cdot e^{\left(-cosTheta\right) \cdot cosTheta} + \left(c + 1\right)}
\end{array}
Initial program 98.0%
lift-*.f32N/A
lift-/.f32N/A
associate-*r/N/A
lower-/.f32N/A
lift-/.f32N/A
associate-*l/N/A
*-lft-identityN/A
lift-sqrt.f32N/A
lift-sqrt.f32N/A
sqrt-undivN/A
lower-sqrt.f32N/A
lower-/.f3298.3
Applied rewrites98.3%
Final simplification98.3%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(*
(/ (- 1.0 cosTheta) (* (sqrt (PI)) cosTheta))
(exp (* (- cosTheta) cosTheta)))
(+ c 1.0))))\begin{array}{l}
\\
\frac{1}{\frac{1 - cosTheta}{\sqrt{\mathsf{PI}\left(\right)} \cdot cosTheta} \cdot e^{\left(-cosTheta\right) \cdot cosTheta} + \left(c + 1\right)}
\end{array}
Initial program 98.0%
Taylor expanded in cosTheta around 0
associate-*r*N/A
lower-/.f32N/A
mul-1-negN/A
cancel-sign-sub-invN/A
*-lft-identityN/A
distribute-rgt-out--N/A
lower-*.f32N/A
lower-sqrt.f32N/A
lower-/.f32N/A
lower-PI.f32N/A
lower--.f3296.3
Applied rewrites96.3%
Applied rewrites96.7%
Applied rewrites96.8%
Final simplification96.8%
(FPCore (cosTheta c)
:precision binary32
(let* ((t_0 (/ 1.0 (+ c 1.0))) (t_1 (sqrt (PI))))
(/
1.0
(/ (+ (/ (- t_0 (/ cosTheta (+ c 1.0))) cosTheta) t_1) (* t_0 t_1)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{c + 1}\\
t_1 := \sqrt{\mathsf{PI}\left(\right)}\\
\frac{1}{\frac{\frac{t\_0 - \frac{cosTheta}{c + 1}}{cosTheta} + t\_1}{t\_0 \cdot t\_1}}
\end{array}
\end{array}
Initial program 98.0%
lift-+.f32N/A
lift-+.f32N/A
flip3-+N/A
clear-numN/A
lift-*.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-/.f32N/A
div-invN/A
associate-*l/N/A
Applied rewrites98.6%
Taylor expanded in cosTheta around 0
lower-/.f32N/A
+-commutativeN/A
mul-1-negN/A
unsub-negN/A
lower--.f32N/A
lower-/.f32N/A
+-commutativeN/A
lower-+.f32N/A
lower-/.f32N/A
+-commutativeN/A
lower-+.f3296.5
Applied rewrites96.5%
Final simplification96.5%
(FPCore (cosTheta c) :precision binary32 (let* ((t_0 (/ 1.0 (+ c 1.0))) (t_1 (sqrt (PI)))) (/ 1.0 (/ (+ (* (/ (- 1.0 cosTheta) cosTheta) t_0) t_1) (* t_0 t_1)))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{c + 1}\\
t_1 := \sqrt{\mathsf{PI}\left(\right)}\\
\frac{1}{\frac{\frac{1 - cosTheta}{cosTheta} \cdot t\_0 + t\_1}{t\_0 \cdot t\_1}}
\end{array}
\end{array}
Initial program 98.0%
lift-+.f32N/A
lift-+.f32N/A
flip3-+N/A
clear-numN/A
lift-*.f32N/A
lift-*.f32N/A
*-commutativeN/A
lift-/.f32N/A
div-invN/A
associate-*l/N/A
Applied rewrites98.6%
Taylor expanded in cosTheta around 0
lower-/.f32N/A
mul-1-negN/A
unsub-negN/A
lower--.f3296.4
Applied rewrites96.4%
Final simplification96.4%
(FPCore (cosTheta c) :precision binary32 (* (sqrt (PI)) cosTheta))
\begin{array}{l}
\\
\sqrt{\mathsf{PI}\left(\right)} \cdot cosTheta
\end{array}
Initial program 98.0%
Taylor expanded in cosTheta around 0
*-commutativeN/A
lower-*.f32N/A
lower-sqrt.f32N/A
lower-PI.f3294.3
Applied rewrites94.3%
(FPCore (cosTheta c) :precision binary32 (/ 1.0 c))
float code(float cosTheta, float c) {
return 1.0f / c;
}
real(4) function code(costheta, c)
real(4), intent (in) :: costheta
real(4), intent (in) :: c
code = 1.0e0 / c
end function
function code(cosTheta, c) return Float32(Float32(1.0) / c) end
function tmp = code(cosTheta, c) tmp = single(1.0) / c; end
\begin{array}{l}
\\
\frac{1}{c}
\end{array}
Initial program 98.0%
Taylor expanded in c around inf
lower-/.f325.1
Applied rewrites5.1%
herbie shell --seed 2024249
(FPCore (cosTheta c)
:name "Beckmann Sample, normalization factor"
:precision binary32
:pre (and (and (< 0.0 cosTheta) (< cosTheta 0.9999)) (and (< -1.0 c) (< c 1.0)))
(/ 1.0 (+ (+ 1.0 c) (* (* (/ 1.0 (sqrt (PI))) (/ (sqrt (- (- 1.0 cosTheta) cosTheta)) cosTheta)) (exp (* (- cosTheta) cosTheta))))))