
(FPCore (k n) :precision binary64 (* (/ 1.0 (sqrt k)) (pow (* (* 2.0 (PI)) n) (/ (- 1.0 k) 2.0))))
\begin{array}{l}
\\
\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 11 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (k n) :precision binary64 (* (/ 1.0 (sqrt k)) (pow (* (* 2.0 (PI)) n) (/ (- 1.0 k) 2.0))))
\begin{array}{l}
\\
\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}
\end{array}
(FPCore (k n) :precision binary64 (let* ((t_0 (* (* 2.0 (PI)) n))) (/ (sqrt t_0) (* (pow (pow t_0 k) 0.5) (sqrt k)))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\\
\frac{\sqrt{t\_0}}{{\left({t\_0}^{k}\right)}^{0.5} \cdot \sqrt{k}}
\end{array}
\end{array}
Initial program 99.6%
lift-*.f64N/A
*-commutativeN/A
lift-/.f64N/A
un-div-invN/A
lift-pow.f64N/A
lift-/.f64N/A
lift--.f64N/A
div-subN/A
metadata-evalN/A
pow-subN/A
associate-/l/N/A
lower-/.f64N/A
Applied rewrites99.7%
Final simplification99.7%
(FPCore (k n) :precision binary64 (let* ((t_0 (* (* 2.0 (PI)) n))) (* (* (pow t_0 (* -0.5 k)) (sqrt t_0)) (/ 1.0 (sqrt k)))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\\
\left({t\_0}^{\left(-0.5 \cdot k\right)} \cdot \sqrt{t\_0}\right) \cdot \frac{1}{\sqrt{k}}
\end{array}
\end{array}
Initial program 99.6%
lift-pow.f64N/A
lift-/.f64N/A
lift--.f64N/A
div-subN/A
metadata-evalN/A
sub-negN/A
+-commutativeN/A
unpow-prod-upN/A
lower-*.f64N/A
Applied rewrites99.7%
Final simplification99.7%
(FPCore (k n)
:precision binary64
(let* ((t_0 (* (* 2.0 (PI)) n)))
(if (<= k 1.0)
(* (pow k -0.5) (sqrt t_0))
(/ (pow t_0 (* -0.5 k)) (sqrt k)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\\
\mathbf{if}\;k \leq 1:\\
\;\;\;\;{k}^{-0.5} \cdot \sqrt{t\_0}\\
\mathbf{else}:\\
\;\;\;\;\frac{{t\_0}^{\left(-0.5 \cdot k\right)}}{\sqrt{k}}\\
\end{array}
\end{array}
if k < 1Initial program 99.2%
Taylor expanded in k around 0
*-commutativeN/A
lower-*.f64N/A
lower-sqrt.f64N/A
lower-sqrt.f64N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f64N/A
lower-PI.f6474.5
Applied rewrites74.5%
Applied rewrites98.1%
if 1 < k Initial program 100.0%
Taylor expanded in k around inf
*-commutativeN/A
lower-*.f64100.0
Applied rewrites100.0%
lift-*.f64N/A
*-commutativeN/A
lift-/.f64N/A
un-div-invN/A
lower-/.f64100.0
Applied rewrites100.0%
Final simplification99.1%
(FPCore (k n) :precision binary64 (* (sqrt (/ 1.0 k)) (pow (* (* 2.0 n) (PI)) (fma k -0.5 0.5))))
\begin{array}{l}
\\
\sqrt{\frac{1}{k}} \cdot {\left(\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)\right)}^{\left(\mathsf{fma}\left(k, -0.5, 0.5\right)\right)}
\end{array}
Initial program 99.6%
Taylor expanded in k around inf
*-commutativeN/A
lower-*.f64N/A
Applied rewrites99.7%
Final simplification99.7%
(FPCore (k n) :precision binary64 (/ (pow (* (* 2.0 (PI)) n) (fma -0.5 k 0.5)) (sqrt k)))
\begin{array}{l}
\\
\frac{{\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\mathsf{fma}\left(-0.5, k, 0.5\right)\right)}}{\sqrt{k}}
\end{array}
Initial program 99.6%
lift-/.f64N/A
lift--.f64N/A
div-subN/A
metadata-evalN/A
sub-negN/A
+-commutativeN/A
div-invN/A
metadata-evalN/A
distribute-rgt-neg-inN/A
metadata-evalN/A
metadata-evalN/A
lower-fma.f64N/A
metadata-eval99.6
Applied rewrites99.6%
lift-*.f64N/A
*-commutativeN/A
lift-/.f64N/A
un-div-invN/A
lower-/.f6499.6
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.6
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.6
lift-fma.f64N/A
*-commutativeN/A
lower-fma.f6499.6
Applied rewrites99.6%
Final simplification99.6%
(FPCore (k n) :precision binary64 (let* ((t_0 (* 2.0 (PI)))) (/ (* (sqrt n) t_0) (sqrt (* t_0 k)))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := 2 \cdot \mathsf{PI}\left(\right)\\
\frac{\sqrt{n} \cdot t\_0}{\sqrt{t\_0 \cdot k}}
\end{array}
\end{array}
Initial program 99.6%
Taylor expanded in k around 0
*-commutativeN/A
lower-*.f64N/A
lower-sqrt.f64N/A
lower-sqrt.f64N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f64N/A
lower-PI.f6436.4
Applied rewrites36.4%
Applied rewrites47.3%
Applied rewrites47.4%
Applied rewrites48.2%
Final simplification48.2%
(FPCore (k n) :precision binary64 (* (sqrt (/ (* 2.0 (PI)) k)) (sqrt n)))
\begin{array}{l}
\\
\sqrt{\frac{2 \cdot \mathsf{PI}\left(\right)}{k}} \cdot \sqrt{n}
\end{array}
Initial program 99.6%
Taylor expanded in k around 0
*-commutativeN/A
lower-*.f64N/A
lower-sqrt.f64N/A
lower-sqrt.f64N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f64N/A
lower-PI.f6436.4
Applied rewrites36.4%
Applied rewrites47.5%
Final simplification47.5%
(FPCore (k n) :precision binary64 (sqrt (/ (* 2.0 (PI)) (/ k n))))
\begin{array}{l}
\\
\sqrt{\frac{2 \cdot \mathsf{PI}\left(\right)}{\frac{k}{n}}}
\end{array}
Initial program 99.6%
Taylor expanded in k around 0
*-commutativeN/A
lower-*.f64N/A
lower-sqrt.f64N/A
lower-sqrt.f64N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f64N/A
lower-PI.f6436.4
Applied rewrites36.4%
Applied rewrites36.6%
Applied rewrites36.6%
Final simplification36.6%
(FPCore (k n) :precision binary64 (sqrt (* (/ n k) (* 2.0 (PI)))))
\begin{array}{l}
\\
\sqrt{\frac{n}{k} \cdot \left(2 \cdot \mathsf{PI}\left(\right)\right)}
\end{array}
Initial program 99.6%
Taylor expanded in k around 0
*-commutativeN/A
lower-*.f64N/A
lower-sqrt.f64N/A
lower-sqrt.f64N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f64N/A
lower-PI.f6436.4
Applied rewrites36.4%
Applied rewrites36.6%
Applied rewrites36.6%
Final simplification36.6%
(FPCore (k n) :precision binary64 (sqrt (* (* (/ (PI) k) n) 2.0)))
\begin{array}{l}
\\
\sqrt{\left(\frac{\mathsf{PI}\left(\right)}{k} \cdot n\right) \cdot 2}
\end{array}
Initial program 99.6%
Taylor expanded in k around 0
*-commutativeN/A
lower-*.f64N/A
lower-sqrt.f64N/A
lower-sqrt.f64N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f64N/A
lower-PI.f6436.4
Applied rewrites36.4%
Applied rewrites36.6%
Applied rewrites36.6%
Final simplification36.6%
(FPCore (k n) :precision binary64 (sqrt (* (/ 2.0 k) (* (PI) n))))
\begin{array}{l}
\\
\sqrt{\frac{2}{k} \cdot \left(\mathsf{PI}\left(\right) \cdot n\right)}
\end{array}
Initial program 99.6%
Taylor expanded in k around 0
*-commutativeN/A
lower-*.f64N/A
lower-sqrt.f64N/A
lower-sqrt.f64N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f64N/A
lower-PI.f6436.4
Applied rewrites36.4%
Applied rewrites36.6%
Applied rewrites36.6%
Final simplification36.6%
herbie shell --seed 2024244
(FPCore (k n)
:name "Migdal et al, Equation (51)"
:precision binary64
(* (/ 1.0 (sqrt k)) (pow (* (* 2.0 (PI)) n) (/ (- 1.0 k) 2.0))))