
(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)))) (* (sqrt n) (sqrt (/ t_0 (* k (pow (* t_0 n) k)))))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := 2 \cdot \mathsf{PI}\left(\right)\\
\sqrt{n} \cdot \sqrt{\frac{t\_0}{k \cdot {\left(t\_0 \cdot n\right)}^{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
lift-/.f64N/A
associate-*l/N/A
*-lft-identityN/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%
(FPCore (k n) :precision binary64 (if (<= k 3.2e-30) (* (sqrt (* (* 2.0 (PI)) n)) (pow k -0.5)) (pow (sqrt (* k (pow (* (* n 2.0) (PI)) (- k 1.0)))) -1.0)))
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;k \leq 3.2 \cdot 10^{-30}:\\
\;\;\;\;\sqrt{\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n} \cdot {k}^{-0.5}\\
\mathbf{else}:\\
\;\;\;\;{\left(\sqrt{k \cdot {\left(\left(n \cdot 2\right) \cdot \mathsf{PI}\left(\right)\right)}^{\left(k - 1\right)}}\right)}^{-1}\\
\end{array}
\end{array}
if k < 3.2e-30Initial 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.f6472.3
Applied rewrites72.3%
Applied rewrites99.5%
if 3.2e-30 < k 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
lift-/.f64N/A
associate-*l/N/A
*-lft-identityN/A
lower-/.f6499.4
Applied rewrites99.4%
lift-pow.f64N/A
lift-sqrt.f64N/A
sqrt-pow2N/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
Applied rewrites99.4%
lift-/.f64N/A
clear-numN/A
lower-/.f64N/A
lift-sqrt.f64N/A
lift-sqrt.f64N/A
sqrt-undivN/A
lower-sqrt.f64N/A
div-invN/A
lift-pow.f64N/A
lift--.f64N/A
pow-subN/A
unpow1N/A
lift-*.f64N/A
lift-*.f64N/A
*-commutativeN/A
lift-PI.f64N/A
Applied rewrites99.3%
Final simplification99.4%
(FPCore (k n) :precision binary64 (* (pow (* (* 2.0 n) (PI)) (fma -0.5 k 0.5)) (sqrt (pow k -1.0))))
\begin{array}{l}
\\
{\left(\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)\right)}^{\left(\mathsf{fma}\left(-0.5, k, 0.5\right)\right)} \cdot \sqrt{{k}^{-1}}
\end{array}
Initial program 99.4%
Taylor expanded in k around inf
*-commutativeN/A
lower-*.f64N/A
Applied rewrites99.4%
Final simplification99.4%
(FPCore (k n)
:precision binary64
(let* ((t_0 (* (* 2.0 (PI)) n)))
(if (<= k 2.2e-31)
(* (sqrt t_0) (pow k -0.5))
(sqrt (/ (pow t_0 (- 1.0 k)) k)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\\
\mathbf{if}\;k \leq 2.2 \cdot 10^{-31}:\\
\;\;\;\;\sqrt{t\_0} \cdot {k}^{-0.5}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{\frac{{t\_0}^{\left(1 - k\right)}}{k}}\\
\end{array}
\end{array}
if k < 2.2000000000000001e-31Initial 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.f6471.8
Applied rewrites71.8%
Applied rewrites99.5%
if 2.2000000000000001e-31 < k 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
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-/.f6498.8
lift-*.f64N/A
*-commutativeN/A
lower-*.f6498.8
lift-*.f64N/A
*-commutativeN/A
lift-*.f6498.8
Applied rewrites98.8%
(FPCore (k n) :precision binary64 (/ (pow (* (* (PI) 2.0) n) (- 0.5 (* 0.5 k))) (sqrt k)))
\begin{array}{l}
\\
\frac{{\left(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot n\right)}^{\left(0.5 - 0.5 \cdot 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
lift-/.f64N/A
associate-*l/N/A
*-lft-identityN/A
lower-/.f6499.4
Applied rewrites99.4%
lift-pow.f64N/A
lift--.f64N/A
pow-subN/A
unpow1N/A
lift-sqrt.f64N/A
pow1/2N/A
lift-sqrt.f64N/A
pow1/2N/A
pow-powN/A
pow-divN/A
lower-pow.f64N/A
lift-*.f64N/A
*-commutativeN/A
lower-*.f64N/A
lower--.f64N/A
lower-*.f6499.4
Applied rewrites99.4%
(FPCore (k n) :precision binary64 (* (sqrt (* (* 2.0 (PI)) n)) (pow k -0.5)))
\begin{array}{l}
\\
\sqrt{\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n} \cdot {k}^{-0.5}
\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 rewrites48.8%
(FPCore (k n) :precision binary64 (* (sqrt n) (sqrt (/ (* 2.0 (PI)) k))))
\begin{array}{l}
\\
\sqrt{n} \cdot \sqrt{\frac{2 \cdot \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 rewrites48.8%
(FPCore (k n) :precision binary64 (sqrt (* (/ n (/ k (PI))) 2.0)))
\begin{array}{l}
\\
\sqrt{\frac{n}{\frac{k}{\mathsf{PI}\left(\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 rewrites37.3%
Applied rewrites37.3%
(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 99.4%
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 rewrites37.3%
(FPCore (k n) :precision binary64 (sqrt (* (* (/ n k) (PI)) 2.0)))
\begin{array}{l}
\\
\sqrt{\left(\frac{n}{k} \cdot \mathsf{PI}\left(\right)\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 rewrites37.3%
Applied rewrites37.3%
(FPCore (k n) :precision binary64 (sqrt (* (* (PI) (/ 2.0 k)) n)))
\begin{array}{l}
\\
\sqrt{\left(\mathsf{PI}\left(\right) \cdot \frac{2}{k}\right) \cdot 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 rewrites37.3%
Applied rewrites37.2%
herbie shell --seed 2024296
(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))))