
(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 12 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 99.4%
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))) (/ (sqrt t_0) (sqrt (* (pow t_0 k) k)))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\\
\frac{\sqrt{t\_0}}{\sqrt{{t\_0}^{k} \cdot k}}
\end{array}
\end{array}
Initial program 99.4%
lift-pow.f64N/A
lift-/.f64N/A
div-invN/A
metadata-evalN/A
pow-unpowN/A
unpow1/2N/A
lower-sqrt.f64N/A
lower-pow.f6499.4
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.4
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.4
Applied rewrites99.4%
lift-*.f64N/A
*-commutativeN/A
lift-/.f64N/A
un-div-invN/A
lift-sqrt.f64N/A
lift-pow.f64N/A
sqrt-pow1N/A
lift--.f64N/A
div-subN/A
metadata-evalN/A
pow-subN/A
pow1/2N/A
lift-sqrt.f64N/A
associate-/r*N/A
associate-/l/N/A
Applied rewrites99.7%
Final simplification99.7%
(FPCore (k n) :precision binary64 (/ (pow (sqrt (* (* 2.0 (PI)) n)) (- 1.0 k)) (sqrt k)))
\begin{array}{l}
\\
\frac{{\left(\sqrt{\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n}\right)}^{\left(1 - k\right)}}{\sqrt{k}}
\end{array}
Initial program 99.4%
lift-pow.f64N/A
lift-/.f64N/A
div-invN/A
metadata-evalN/A
pow-unpowN/A
unpow1/2N/A
lower-sqrt.f64N/A
lower-pow.f6499.4
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.4
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.4
Applied rewrites99.4%
lift-*.f64N/A
*-commutativeN/A
lift-/.f64N/A
un-div-invN/A
lower-/.f6499.5
Applied rewrites99.5%
(FPCore (k n) :precision binary64 (if (<= k 2.5e-15) (* (sqrt (* 2.0 n)) (sqrt (/ (PI) k))) (sqrt (/ (pow (* (* 2.0 (PI)) n) (- 1.0 k)) k))))
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;k \leq 2.5 \cdot 10^{-15}:\\
\;\;\;\;\sqrt{2 \cdot n} \cdot \sqrt{\frac{\mathsf{PI}\left(\right)}{k}}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{\frac{{\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(1 - k\right)}}{k}}\\
\end{array}
\end{array}
if k < 2.5e-15Initial program 99.1%
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.f6473.3
Applied rewrites73.3%
Applied rewrites72.8%
Applied rewrites72.9%
Applied rewrites99.1%
if 2.5e-15 < k Initial program 99.8%
lift-pow.f64N/A
lift-/.f64N/A
div-invN/A
metadata-evalN/A
pow-unpowN/A
unpow1/2N/A
lower-sqrt.f64N/A
lower-pow.f6499.8
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.8
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.8
Applied rewrites99.8%
lift-*.f64N/A
lift-/.f64N/A
associate-*l/N/A
*-lft-identityN/A
lift-sqrt.f64N/A
lift-sqrt.f64N/A
sqrt-undivN/A
lower-sqrt.f64N/A
lower-/.f6499.8
lift-*.f64N/A
lift-*.f64N/A
*-commutativeN/A
lift-*.f64N/A
*-commutativeN/A
lift-*.f6499.8
Applied rewrites99.8%
Final simplification99.4%
(FPCore (k n) :precision binary64 (/ (pow (* (* 2.0 (PI)) n) (* (- 1.0 k) 0.5)) (sqrt k)))
\begin{array}{l}
\\
\frac{{\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\left(1 - k\right) \cdot 0.5\right)}}{\sqrt{k}}
\end{array}
Initial program 99.4%
lift-pow.f64N/A
lift-/.f64N/A
div-invN/A
metadata-evalN/A
pow-unpowN/A
unpow1/2N/A
lower-sqrt.f64N/A
lower-pow.f6499.4
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.4
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.4
Applied rewrites99.4%
lift-*.f64N/A
*-commutativeN/A
lift-/.f64N/A
un-div-invN/A
lower-/.f6499.5
Applied rewrites99.5%
lift-pow.f64N/A
lift-sqrt.f64N/A
sqrt-pow2N/A
lift--.f64N/A
lower-pow.f64N/A
lift-*.f64N/A
*-commutativeN/A
lift-*.f64N/A
*-commutativeN/A
lift-*.f64N/A
lift-*.f64N/A
lift--.f64N/A
clear-numN/A
associate-/r/N/A
metadata-evalN/A
lower-*.f6499.5
Applied rewrites99.5%
Final simplification99.5%
(FPCore (k n)
:precision binary64
(let* ((t_0 (* (* 2.0 (PI)) n)))
(if (<= t_0 5e+16)
(sqrt (* (* (/ (PI) k) n) 2.0))
(/ (* (- -2.0) (* (PI) n)) (sqrt (* k t_0))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\\
\mathbf{if}\;t\_0 \leq 5 \cdot 10^{+16}:\\
\;\;\;\;\sqrt{\left(\frac{\mathsf{PI}\left(\right)}{k} \cdot n\right) \cdot 2}\\
\mathbf{else}:\\
\;\;\;\;\frac{\left(--2\right) \cdot \left(\mathsf{PI}\left(\right) \cdot n\right)}{\sqrt{k \cdot t\_0}}\\
\end{array}
\end{array}
if (*.f64 (*.f64 #s(literal 2 binary64) (PI.f64)) n) < 5e16Initial 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.f6448.7
Applied rewrites48.7%
Applied rewrites48.9%
Applied rewrites49.0%
if 5e16 < (*.f64 (*.f64 #s(literal 2 binary64) (PI.f64)) n) Initial program 99.4%
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.f6421.4
Applied rewrites21.4%
Applied rewrites50.6%
Applied rewrites50.6%
Applied rewrites78.5%
Final simplification61.4%
(FPCore (k n) :precision binary64 (* (sqrt (* 2.0 n)) (sqrt (/ (PI) k))))
\begin{array}{l}
\\
\sqrt{2 \cdot n} \cdot \sqrt{\frac{\mathsf{PI}\left(\right)}{k}}
\end{array}
Initial program 99.4%
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.f6437.2
Applied rewrites37.2%
Applied rewrites37.0%
Applied rewrites37.0%
Applied rewrites49.7%
Final simplification49.7%
(FPCore (k n) :precision binary64 (* (sqrt (* (PI) n)) (sqrt (/ 2.0 k))))
\begin{array}{l}
\\
\sqrt{\mathsf{PI}\left(\right) \cdot n} \cdot \sqrt{\frac{2}{k}}
\end{array}
Initial program 99.4%
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.f6437.2
Applied rewrites37.2%
Applied rewrites37.0%
Applied rewrites49.7%
Final simplification49.7%
(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 99.4%
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.f6437.2
Applied rewrites37.2%
Applied rewrites49.6%
Final simplification49.6%
(FPCore (k n) :precision binary64 (* (sqrt (/ (* (PI) n) k)) (sqrt 2.0)))
\begin{array}{l}
\\
\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}} \cdot \sqrt{2}
\end{array}
Initial program 99.4%
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.f6437.2
Applied rewrites37.2%
Final simplification37.2%
(FPCore (k n) :precision binary64 (sqrt (/ (* 2.0 n) (/ k (PI)))))
\begin{array}{l}
\\
\sqrt{\frac{2 \cdot n}{\frac{k}{\mathsf{PI}\left(\right)}}}
\end{array}
Initial program 99.4%
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.f6437.2
Applied rewrites37.2%
Applied rewrites37.0%
Applied rewrites37.0%
Applied rewrites37.0%
(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 99.4%
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.f6437.2
Applied rewrites37.2%
Applied rewrites37.0%
Applied rewrites37.0%
Final simplification37.0%
herbie shell --seed 2024271
(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))))