
(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 10 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 (/ (sqrt (* (* 2.0 (PI)) n)) (* (pow (* (* 2.0 n) (PI)) (* 0.5 k)) (sqrt k))))
\begin{array}{l}
\\
\frac{\sqrt{\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n}}{{\left(\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)\right)}^{\left(0.5 \cdot k\right)} \cdot \sqrt{k}}
\end{array}
Initial program 99.5%
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%
lift-pow.f64N/A
lift-pow.f64N/A
pow-powN/A
*-commutativeN/A
lower-pow.f64N/A
lift-*.f64N/A
lift-*.f64N/A
associate-*r*N/A
lift-*.f64N/A
*-commutativeN/A
lift-*.f64N/A
associate-*r*N/A
lower-*.f64N/A
lower-*.f64N/A
lower-*.f6499.7
Applied rewrites99.7%
Final simplification99.7%
(FPCore (k n) :precision binary64 (let* ((t_0 (* (* 2.0 n) (PI)))) (/ (sqrt t_0) (sqrt (* (pow t_0 k) k)))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)\\
\frac{\sqrt{t\_0}}{\sqrt{{t\_0}^{k} \cdot k}}
\end{array}
\end{array}
Initial program 99.5%
lift-pow.f64N/A
lift-/.f64N/A
clear-numN/A
associate-/r/N/A
metadata-evalN/A
pow-unpowN/A
remove-double-negN/A
neg-sub0N/A
pow-subN/A
metadata-evalN/A
lower-/.f64N/A
lower-pow.f64N/A
unpow1/2N/A
lower-sqrt.f64N/A
lift-*.f64N/A
*-commutativeN/A
lower-*.f64N/A
lift-*.f64N/A
*-commutativeN/A
lower-*.f64N/A
neg-sub0N/A
lift--.f64N/A
sub-negN/A
Applied rewrites99.5%
lift-*.f64N/A
lift-/.f64N/A
lift-/.f64N/A
frac-timesN/A
metadata-evalN/A
lift-pow.f64N/A
lift--.f64N/A
sub-negN/A
metadata-evalN/A
unpow-prod-upN/A
lift-sqrt.f64N/A
sqrt-pow2N/A
sqrt-pow1N/A
lift-pow.f64N/A
unpow1/2N/A
lift-pow.f64N/A
inv-powN/A
Applied rewrites99.6%
Final simplification99.6%
(FPCore (k n) :precision binary64 (* (sqrt (/ 1.0 k)) (pow (* (* 2.0 n) (PI)) (fma -0.5 k 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(-0.5, k, 0.5\right)\right)}
\end{array}
Initial program 99.5%
Taylor expanded in k around inf
*-commutativeN/A
lower-*.f64N/A
Applied rewrites99.6%
Final simplification99.6%
(FPCore (k n) :precision binary64 (if (<= k 1.06e-20) (/ (sqrt (* (PI) n)) (sqrt (* 0.5 k))) (sqrt (/ (pow (* (* 2.0 n) (PI)) (- 1.0 k)) k))))
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;k \leq 1.06 \cdot 10^{-20}:\\
\;\;\;\;\frac{\sqrt{\mathsf{PI}\left(\right) \cdot n}}{\sqrt{0.5 \cdot k}}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{\frac{{\left(\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)\right)}^{\left(1 - k\right)}}{k}}\\
\end{array}
\end{array}
if k < 1.06e-20Initial program 99.3%
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.f6471.7
Applied rewrites71.7%
Applied rewrites71.8%
Applied rewrites72.3%
Applied rewrites99.5%
if 1.06e-20 < k Initial program 99.7%
lift-pow.f64N/A
lift-/.f64N/A
clear-numN/A
associate-/r/N/A
metadata-evalN/A
pow-unpowN/A
remove-double-negN/A
neg-sub0N/A
pow-subN/A
metadata-evalN/A
lower-/.f64N/A
lower-pow.f64N/A
unpow1/2N/A
lower-sqrt.f64N/A
lift-*.f64N/A
*-commutativeN/A
lower-*.f64N/A
lift-*.f64N/A
*-commutativeN/A
lower-*.f64N/A
neg-sub0N/A
lift--.f64N/A
sub-negN/A
Applied rewrites99.7%
lift-*.f64N/A
lift-/.f64N/A
lift-/.f64N/A
frac-timesN/A
metadata-evalN/A
lift-pow.f64N/A
lift--.f64N/A
sub-negN/A
metadata-evalN/A
unpow-prod-upN/A
lift-sqrt.f64N/A
sqrt-pow2N/A
sqrt-pow1N/A
lift-pow.f64N/A
unpow1/2N/A
lift-pow.f64N/A
inv-powN/A
Applied rewrites100.0%
lift-/.f64N/A
lift-sqrt.f64N/A
lift-sqrt.f64N/A
sqrt-undivN/A
lower-sqrt.f64N/A
lift-*.f64N/A
*-commutativeN/A
associate-/r*N/A
lower-/.f64N/A
Applied rewrites99.7%
Final simplification99.6%
(FPCore (k n) :precision binary64 (/ (pow (* (* 2.0 n) (PI)) (fma -0.5 k 0.5)) (sqrt k)))
\begin{array}{l}
\\
\frac{{\left(\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)\right)}^{\left(\mathsf{fma}\left(-0.5, k, 0.5\right)\right)}}{\sqrt{k}}
\end{array}
Initial program 99.5%
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%
lift-pow.f64N/A
lift-pow.f64N/A
pow-powN/A
*-commutativeN/A
lower-pow.f64N/A
lift-*.f64N/A
lift-*.f64N/A
associate-*r*N/A
lift-*.f64N/A
*-commutativeN/A
lift-*.f64N/A
associate-*r*N/A
lower-*.f64N/A
lower-*.f64N/A
lower-*.f6499.7
Applied rewrites99.7%
Applied rewrites99.5%
(FPCore (k n) :precision binary64 (/ (sqrt (* (PI) n)) (sqrt (* 0.5 k))))
\begin{array}{l}
\\
\frac{\sqrt{\mathsf{PI}\left(\right) \cdot n}}{\sqrt{0.5 \cdot k}}
\end{array}
Initial program 99.5%
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.f6437.8
Applied rewrites37.8%
Applied rewrites37.9%
Applied rewrites38.1%
Applied rewrites51.4%
(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 99.5%
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.f6437.8
Applied rewrites37.8%
Applied rewrites51.4%
Final simplification51.4%
(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 99.5%
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.f6437.8
Applied rewrites37.8%
Applied rewrites37.9%
Applied rewrites37.9%
(FPCore (k n) :precision binary64 (sqrt (* (/ (* 2.0 (PI)) k) n)))
\begin{array}{l}
\\
\sqrt{\frac{2 \cdot \mathsf{PI}\left(\right)}{k} \cdot n}
\end{array}
Initial program 99.5%
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.f6437.8
Applied rewrites37.8%
Applied rewrites37.9%
Applied rewrites37.9%
(FPCore (k n) :precision binary64 (sqrt (* (/ (* (PI) n) k) 2.0)))
\begin{array}{l}
\\
\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}
\end{array}
Initial program 99.5%
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.f6437.8
Applied rewrites37.8%
Applied rewrites37.9%
Taylor expanded in k around 0
Applied rewrites37.9%
herbie shell --seed 2024308
(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))))