
(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 11 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
(-
(- -1.0 c)
(*
(exp (* (- cosTheta) cosTheta))
(/ (sqrt (- (- 1.0 cosTheta) cosTheta)) (* (sqrt (PI)) cosTheta))))))\begin{array}{l}
\\
\frac{-1}{\left(-1 - c\right) - e^{\left(-cosTheta\right) \cdot cosTheta} \cdot \frac{\sqrt{\left(1 - cosTheta\right) - cosTheta}}{\sqrt{\mathsf{PI}\left(\right)} \cdot cosTheta}}
\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
(let* ((t_0 (pow (exp cosTheta) cosTheta)) (t_1 (* (fma c c -1.0) cosTheta)))
(/
(*
(-
t_1
(* (/ (sqrt (/ (- (- 1.0 cosTheta) cosTheta) (PI))) t_0) (- c 1.0)))
(* cosTheta (- c 1.0)))
(+
(* (/ (- cosTheta (- 1.0 cosTheta)) (PI)) (pow (/ t_0 (- c 1.0)) -2.0))
(pow t_1 2.0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := {\left(e^{cosTheta}\right)}^{cosTheta}\\
t_1 := \mathsf{fma}\left(c, c, -1\right) \cdot cosTheta\\
\frac{\left(t\_1 - \frac{\sqrt{\frac{\left(1 - cosTheta\right) - cosTheta}{\mathsf{PI}\left(\right)}}}{t\_0} \cdot \left(c - 1\right)\right) \cdot \left(cosTheta \cdot \left(c - 1\right)\right)}{\frac{cosTheta - \left(1 - cosTheta\right)}{\mathsf{PI}\left(\right)} \cdot {\left(\frac{t\_0}{c - 1}\right)}^{-2} + {t\_1}^{2}}
\end{array}
\end{array}
Initial program 98.0%
lift-+.f32N/A
lift-+.f32N/A
+-commutativeN/A
flip-+N/A
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
lift-/.f32N/A
associate-*r/N/A
associate-*r/N/A
frac-addN/A
Applied rewrites92.3%
Applied rewrites98.6%
lift-*.f32N/A
lift-/.f32N/A
associate-*l/N/A
lower-/.f32N/A
Applied rewrites59.6%
Final simplification81.9%
(FPCore (cosTheta c)
:precision binary32
(/
-1.0
(-
(- -1.0 c)
(*
(/ (sqrt (/ (- 1.0 (+ cosTheta cosTheta)) (PI))) cosTheta)
(exp (* (- cosTheta) cosTheta))))))\begin{array}{l}
\\
\frac{-1}{\left(-1 - c\right) - \frac{\sqrt{\frac{1 - \left(cosTheta + cosTheta\right)}{\mathsf{PI}\left(\right)}}}{cosTheta} \cdot e^{\left(-cosTheta\right) \cdot cosTheta}}
\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-/.f3298.2
Applied rewrites98.2%
lift--.f32N/A
sub-negN/A
lift--.f32N/A
lift-neg.f32N/A
associate-+l-N/A
lower--.f32N/A
lower--.f3298.2
Applied rewrites98.2%
Final simplification98.2%
(FPCore (cosTheta c)
:precision binary32
(/
-1.0
(-
(- -1.0 c)
(*
(/ (sqrt (/ (- (- 1.0 cosTheta) cosTheta) (PI))) cosTheta)
(exp (* (- cosTheta) cosTheta))))))\begin{array}{l}
\\
\frac{-1}{\left(-1 - c\right) - \frac{\sqrt{\frac{\left(1 - cosTheta\right) - cosTheta}{\mathsf{PI}\left(\right)}}}{cosTheta} \cdot e^{\left(-cosTheta\right) \cdot cosTheta}}
\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-/.f3298.2
Applied rewrites98.2%
Final simplification98.2%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
1.0
(*
(/ (sqrt (/ (- (- 1.0 cosTheta) cosTheta) (PI))) cosTheta)
(exp (* (- cosTheta) cosTheta))))))\begin{array}{l}
\\
\frac{1}{1 + \frac{\sqrt{\frac{\left(1 - cosTheta\right) - cosTheta}{\mathsf{PI}\left(\right)}}}{cosTheta} \cdot e^{\left(-cosTheta\right) \cdot cosTheta}}
\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-/.f3298.2
Applied rewrites98.2%
Taylor expanded in c around 0
Applied rewrites98.1%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(*
(* (/ -1.0 (* (sqrt (PI)) cosTheta)) (+ -1.0 cosTheta))
(exp (* (- cosTheta) cosTheta)))
1.0)))\begin{array}{l}
\\
\frac{1}{\left(\frac{-1}{\sqrt{\mathsf{PI}\left(\right)} \cdot cosTheta} \cdot \left(-1 + cosTheta\right)\right) \cdot e^{\left(-cosTheta\right) \cdot cosTheta} + 1}
\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--.f3295.6
Applied rewrites95.6%
Taylor expanded in c around 0
Applied rewrites95.5%
Applied rewrites96.0%
Final simplification96.0%
(FPCore (cosTheta c)
:precision binary32
(/
-1.0
(-
(- -1.0 c)
(*
(/ (- 1.0 cosTheta) (* (sqrt (PI)) cosTheta))
(exp (* (- cosTheta) cosTheta))))))\begin{array}{l}
\\
\frac{-1}{\left(-1 - c\right) - \frac{1 - cosTheta}{\sqrt{\mathsf{PI}\left(\right)} \cdot cosTheta} \cdot e^{\left(-cosTheta\right) \cdot cosTheta}}
\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--.f3295.6
Applied rewrites95.6%
Applied rewrites96.1%
Final simplification96.1%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(*
(/ (- 1.0 cosTheta) (* (sqrt (PI)) cosTheta))
(exp (* (- cosTheta) cosTheta)))
1.0)))\begin{array}{l}
\\
\frac{1}{\frac{1 - cosTheta}{\sqrt{\mathsf{PI}\left(\right)} \cdot cosTheta} \cdot e^{\left(-cosTheta\right) \cdot cosTheta} + 1}
\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--.f3295.6
Applied rewrites95.6%
Taylor expanded in c around 0
Applied rewrites95.5%
Applied rewrites96.0%
Final simplification96.0%
(FPCore (cosTheta c) :precision binary32 (* (- (sqrt (PI)) (* (- (+ 1.0 c) (sqrt (/ 1.0 (PI)))) (* (PI) cosTheta))) cosTheta))
\begin{array}{l}
\\
\left(\sqrt{\mathsf{PI}\left(\right)} - \left(\left(1 + c\right) - \sqrt{\frac{1}{\mathsf{PI}\left(\right)}}\right) \cdot \left(\mathsf{PI}\left(\right) \cdot cosTheta\right)\right) \cdot cosTheta
\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%
lift-/.f32N/A
lift-*.f32N/A
associate-/r*N/A
lift-/.f32N/A
clear-numN/A
lower-/.f32N/A
lower-/.f3298.6
Applied rewrites98.6%
Taylor expanded in cosTheta around 0
*-commutativeN/A
lower-*.f32N/A
Applied rewrites95.7%
Final simplification95.7%
(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.f3293.7
Applied rewrites93.7%
(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-/.f325.0
Applied rewrites5.0%
herbie shell --seed 2024264
(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))))))