Migdal et al, Equation (51)

Average Accuracy: 99.2% → 99.3%

Time: 15.2s

Precision: binary64

Cost: 20036

Math

\[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]

↓

\[\begin{array}{l} \mathbf{if}\;k \leq 7.2 \cdot 10^{-17}:\\ \;\;\;\;\sqrt{\frac{\pi}{k}} \cdot \sqrt{2 \cdot n}\\ \mathbf{else}:\\ \;\;\;\;\frac{1}{\sqrt{k \cdot {\left(n \cdot \left(\pi \cdot 2\right)\right)}^{\left(k + -1\right)}}}\\ \end{array} \]

FPCore

(FPCore (k n)
 :precision binary64
 (* (/ 1.0 (sqrt k)) (pow (* (* 2.0 PI) n) (/ (- 1.0 k) 2.0))))

↓

(FPCore (k n)
 :precision binary64
 (if (<= k 7.2e-17)
   (* (sqrt (/ PI k)) (sqrt (* 2.0 n)))
   (/ 1.0 (sqrt (* k (pow (* n (* PI 2.0)) (+ k -1.0)))))))

C

double code(double k, double n) {
	return (1.0 / sqrt(k)) * pow(((2.0 * ((double) M_PI)) * n), ((1.0 - k) / 2.0));
}

↓

double code(double k, double n) {
	double tmp;
	if (k <= 7.2e-17) {
		tmp = sqrt((((double) M_PI) / k)) * sqrt((2.0 * n));
	} else {
		tmp = 1.0 / sqrt((k * pow((n * (((double) M_PI) * 2.0)), (k + -1.0))));
	}
	return tmp;
}

Java

public static double code(double k, double n) {
	return (1.0 / Math.sqrt(k)) * Math.pow(((2.0 * Math.PI) * n), ((1.0 - k) / 2.0));
}

↓

public static double code(double k, double n) {
	double tmp;
	if (k <= 7.2e-17) {
		tmp = Math.sqrt((Math.PI / k)) * Math.sqrt((2.0 * n));
	} else {
		tmp = 1.0 / Math.sqrt((k * Math.pow((n * (Math.PI * 2.0)), (k + -1.0))));
	}
	return tmp;
}

Python

def code(k, n):
	return (1.0 / math.sqrt(k)) * math.pow(((2.0 * math.pi) * n), ((1.0 - k) / 2.0))

↓

def code(k, n):
	tmp = 0
	if k <= 7.2e-17:
		tmp = math.sqrt((math.pi / k)) * math.sqrt((2.0 * n))
	else:
		tmp = 1.0 / math.sqrt((k * math.pow((n * (math.pi * 2.0)), (k + -1.0))))
	return tmp

Julia

function code(k, n)
	return Float64(Float64(1.0 / sqrt(k)) * (Float64(Float64(2.0 * pi) * n) ^ Float64(Float64(1.0 - k) / 2.0)))
end

↓

function code(k, n)
	tmp = 0.0
	if (k <= 7.2e-17)
		tmp = Float64(sqrt(Float64(pi / k)) * sqrt(Float64(2.0 * n)));
	else
		tmp = Float64(1.0 / sqrt(Float64(k * (Float64(n * Float64(pi * 2.0)) ^ Float64(k + -1.0)))));
	end
	return tmp
end

MATLAB

function tmp = code(k, n)
	tmp = (1.0 / sqrt(k)) * (((2.0 * pi) * n) ^ ((1.0 - k) / 2.0));
end

↓

function tmp_2 = code(k, n)
	tmp = 0.0;
	if (k <= 7.2e-17)
		tmp = sqrt((pi / k)) * sqrt((2.0 * n));
	else
		tmp = 1.0 / sqrt((k * ((n * (pi * 2.0)) ^ (k + -1.0))));
	end
	tmp_2 = tmp;
end

Wolfram

code[k_, n_] := N[(N[(1.0 / N[Sqrt[k], $MachinePrecision]), $MachinePrecision] * N[Power[N[(N[(2.0 * Pi), $MachinePrecision] * n), $MachinePrecision], N[(N[(1.0 - k), $MachinePrecision] / 2.0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]

↓

code[k_, n_] := If[LessEqual[k, 7.2e-17], N[(N[Sqrt[N[(Pi / k), $MachinePrecision]], $MachinePrecision] * N[Sqrt[N[(2.0 * n), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], N[(1.0 / N[Sqrt[N[(k * N[Power[N[(n * N[(Pi * 2.0), $MachinePrecision]), $MachinePrecision], N[(k + -1.0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]]

Derivation

1. Split input into 2 regimes

2. if k < 7.1999999999999999e-17

   1. Initial program 99.2%

      \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]

   2. Simplified 99.3%

      \[\leadsto \color{blue}{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 - \frac{k}{2}\right)}}{\sqrt{k}}} \]
      Proof

      [Start] 99.2	\[ \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
      associate-*l/ [=>] 99.3	\[ \color{blue}{\frac{1 \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}}} \]
      *-lft-identity [=>] 99.3	\[ \frac{\color{blue}{{\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}}{\sqrt{k}} \]
      sqr-pow [=>] 98.9	\[ \frac{\color{blue}{{\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{\frac{1 - k}{2}}{2}\right)} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{\frac{1 - k}{2}}{2}\right)}}}{\sqrt{k}} \]
      sqr-pow [<=] 99.3	\[ \frac{\color{blue}{{\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}}{\sqrt{k}} \]
      *-commutative [=>] 99.3	\[ \frac{{\left(\color{blue}{\left(\pi \cdot 2\right)} \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}} \]
      associate-*l* [=>] 99.3	\[ \frac{{\color{blue}{\left(\pi \cdot \left(2 \cdot n\right)\right)}}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}} \]
      div-sub [=>] 99.3	\[ \frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\color{blue}{\left(\frac{1}{2} - \frac{k}{2}\right)}}}{\sqrt{k}} \]
      metadata-eval [=>] 99.3	\[ \frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(\color{blue}{0.5} - \frac{k}{2}\right)}}{\sqrt{k}} \]

   3. Applied egg-rr 73.2%

      \[\leadsto \color{blue}{\sqrt{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(2 \cdot \left(0.5 + k \cdot -0.5\right)\right)}}{k}}} \]
      Proof

      [Start] 99.3	\[ \frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 - \frac{k}{2}\right)}}{\sqrt{k}} \]
      add-sqr-sqrt [=>] 98.9	\[ \color{blue}{\sqrt{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 - \frac{k}{2}\right)}}{\sqrt{k}}} \cdot \sqrt{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 - \frac{k}{2}\right)}}{\sqrt{k}}}} \]
      sqrt-unprod [=>] 73.0	\[ \color{blue}{\sqrt{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 - \frac{k}{2}\right)}}{\sqrt{k}} \cdot \frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 - \frac{k}{2}\right)}}{\sqrt{k}}}} \]
      frac-times [=>] 72.9	\[ \sqrt{\color{blue}{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 - \frac{k}{2}\right)} \cdot {\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 - \frac{k}{2}\right)}}{\sqrt{k} \cdot \sqrt{k}}}} \]
      add-sqr-sqrt [<=] 73.0	\[ \sqrt{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 - \frac{k}{2}\right)} \cdot {\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 - \frac{k}{2}\right)}}{\color{blue}{k}}} \]
      pow-sqr [=>] 73.2	\[ \sqrt{\frac{\color{blue}{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(2 \cdot \left(0.5 - \frac{k}{2}\right)\right)}}}{k}} \]
      sub-neg [=>] 73.2	\[ \sqrt{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(2 \cdot \color{blue}{\left(0.5 + \left(-\frac{k}{2}\right)\right)}\right)}}{k}} \]
      div-inv [=>] 73.2	\[ \sqrt{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(2 \cdot \left(0.5 + \left(-\color{blue}{k \cdot \frac{1}{2}}\right)\right)\right)}}{k}} \]
      metadata-eval [=>] 73.2	\[ \sqrt{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(2 \cdot \left(0.5 + \left(-k \cdot \color{blue}{0.5}\right)\right)\right)}}{k}} \]
      distribute-rgt-neg-in [=>] 73.2	\[ \sqrt{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(2 \cdot \left(0.5 + \color{blue}{k \cdot \left(-0.5\right)}\right)\right)}}{k}} \]
      metadata-eval [=>] 73.2	\[ \sqrt{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(2 \cdot \left(0.5 + k \cdot \color{blue}{-0.5}\right)\right)}}{k}} \]

   4. Simplified 73.2%

      \[\leadsto \color{blue}{\sqrt{\frac{{\left(n \cdot \left(2 \cdot \pi\right)\right)}^{\left(1 + k \cdot -1\right)}}{k}}} \]
      Proof

      [Start] 73.2	\[ \sqrt{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(2 \cdot \left(0.5 + k \cdot -0.5\right)\right)}}{k}} \]
      associate-*r* [=>] 73.2	\[ \sqrt{\frac{{\color{blue}{\left(\left(\pi \cdot 2\right) \cdot n\right)}}^{\left(2 \cdot \left(0.5 + k \cdot -0.5\right)\right)}}{k}} \]
      *-commutative [=>] 73.2	\[ \sqrt{\frac{{\color{blue}{\left(n \cdot \left(\pi \cdot 2\right)\right)}}^{\left(2 \cdot \left(0.5 + k \cdot -0.5\right)\right)}}{k}} \]
      *-commutative [<=] 73.2	\[ \sqrt{\frac{{\left(n \cdot \color{blue}{\left(2 \cdot \pi\right)}\right)}^{\left(2 \cdot \left(0.5 + k \cdot -0.5\right)\right)}}{k}} \]
      distribute-rgt-in [=>] 73.2	\[ \sqrt{\frac{{\left(n \cdot \left(2 \cdot \pi\right)\right)}^{\color{blue}{\left(0.5 \cdot 2 + \left(k \cdot -0.5\right) \cdot 2\right)}}}{k}} \]
      metadata-eval [=>] 73.2	\[ \sqrt{\frac{{\left(n \cdot \left(2 \cdot \pi\right)\right)}^{\left(\color{blue}{1} + \left(k \cdot -0.5\right) \cdot 2\right)}}{k}} \]
      associate-*l* [=>] 73.2	\[ \sqrt{\frac{{\left(n \cdot \left(2 \cdot \pi\right)\right)}^{\left(1 + \color{blue}{k \cdot \left(-0.5 \cdot 2\right)}\right)}}{k}} \]
      metadata-eval [=>] 73.2	\[ \sqrt{\frac{{\left(n \cdot \left(2 \cdot \pi\right)\right)}^{\left(1 + k \cdot \color{blue}{-1}\right)}}{k}} \]

   5. Taylor expanded in k around 0 73.2%

      \[\leadsto \sqrt{\color{blue}{2 \cdot \frac{n \cdot \pi}{k}}} \]

   6. Simplified 73.2%

      \[\leadsto \sqrt{\color{blue}{2 \cdot \left(\frac{n}{k} \cdot \pi\right)}} \]
      Proof

      [Start] 73.2	\[ \sqrt{2 \cdot \frac{n \cdot \pi}{k}} \]
      associate-/l* [=>] 73.2	\[ \sqrt{2 \cdot \color{blue}{\frac{n}{\frac{k}{\pi}}}} \]
      associate-/r/ [=>] 73.2	\[ \sqrt{2 \cdot \color{blue}{\left(\frac{n}{k} \cdot \pi\right)}} \]

   7. Taylor expanded in n around 0 73.2%

      \[\leadsto \sqrt{2 \cdot \color{blue}{\frac{n \cdot \pi}{k}}} \]

   8. Simplified 73.1%

      \[\leadsto \sqrt{2 \cdot \color{blue}{\left(n \cdot \frac{\pi}{k}\right)}} \]
      Proof

      [Start] 73.2	\[ \sqrt{2 \cdot \frac{n \cdot \pi}{k}} \]
      associate-*r/ [<=] 73.1	\[ \sqrt{2 \cdot \color{blue}{\left(n \cdot \frac{\pi}{k}\right)}} \]

   9. Applied egg-rr 99.3%

      \[\leadsto \color{blue}{\sqrt{2 \cdot n} \cdot \sqrt{\frac{\pi}{k}}} \]
      Proof

      [Start] 73.1	\[ \sqrt{2 \cdot \left(n \cdot \frac{\pi}{k}\right)} \]
      associate-*r* [=>] 73.1	\[ \sqrt{\color{blue}{\left(2 \cdot n\right) \cdot \frac{\pi}{k}}} \]
      sqrt-prod [=>] 99.3	\[ \color{blue}{\sqrt{2 \cdot n} \cdot \sqrt{\frac{\pi}{k}}} \]

   10. Simplified 99.3%

       \[\leadsto \color{blue}{\sqrt{\frac{\pi}{k}} \cdot \sqrt{n \cdot 2}} \]
       Proof

       [Start] 99.3	\[ \sqrt{2 \cdot n} \cdot \sqrt{\frac{\pi}{k}} \]
       *-commutative [=>] 99.3	\[ \color{blue}{\sqrt{\frac{\pi}{k}} \cdot \sqrt{2 \cdot n}} \]
       *-commutative [=>] 99.3	\[ \sqrt{\frac{\pi}{k}} \cdot \sqrt{\color{blue}{n \cdot 2}} \]

   if 7.1999999999999999e-17 < k

   1. Initial program 99.4%

      \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]

   2. Simplified 99.4%

      \[\leadsto \color{blue}{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 - \frac{k}{2}\right)}}{\sqrt{k}}} \]
      Proof

      [Start] 99.4	\[ \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
      associate-*l/ [=>] 99.4	\[ \color{blue}{\frac{1 \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}}} \]
      *-lft-identity [=>] 99.4	\[ \frac{\color{blue}{{\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}}{\sqrt{k}} \]
      sqr-pow [=>] 99.3	\[ \frac{\color{blue}{{\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{\frac{1 - k}{2}}{2}\right)} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{\frac{1 - k}{2}}{2}\right)}}}{\sqrt{k}} \]
      sqr-pow [<=] 99.4	\[ \frac{\color{blue}{{\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}}{\sqrt{k}} \]
      *-commutative [=>] 99.4	\[ \frac{{\left(\color{blue}{\left(\pi \cdot 2\right)} \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}} \]
      associate-*l* [=>] 99.4	\[ \frac{{\color{blue}{\left(\pi \cdot \left(2 \cdot n\right)\right)}}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}} \]
      div-sub [=>] 99.4	\[ \frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\color{blue}{\left(\frac{1}{2} - \frac{k}{2}\right)}}}{\sqrt{k}} \]
      metadata-eval [=>] 99.4	\[ \frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(\color{blue}{0.5} - \frac{k}{2}\right)}}{\sqrt{k}} \]

   3. Applied egg-rr 99.6%

      \[\leadsto \frac{\color{blue}{\frac{\sqrt{\pi \cdot \left(2 \cdot n\right)}}{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 \cdot k\right)}}}}{\sqrt{k}} \]
      Proof

      [Start] 99.4	\[ \frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 - \frac{k}{2}\right)}}{\sqrt{k}} \]
      pow-sub [=>] 99.6	\[ \frac{\color{blue}{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{0.5}}{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(\frac{k}{2}\right)}}}}{\sqrt{k}} \]
      unpow1/2 [=>] 99.6	\[ \frac{\frac{\color{blue}{\sqrt{\pi \cdot \left(2 \cdot n\right)}}}{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(\frac{k}{2}\right)}}}{\sqrt{k}} \]
      div-inv [=>] 99.6	\[ \frac{\frac{\sqrt{\pi \cdot \left(2 \cdot n\right)}}{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\color{blue}{\left(k \cdot \frac{1}{2}\right)}}}}{\sqrt{k}} \]
      metadata-eval [=>] 99.6	\[ \frac{\frac{\sqrt{\pi \cdot \left(2 \cdot n\right)}}{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(k \cdot \color{blue}{0.5}\right)}}}{\sqrt{k}} \]
      *-commutative [=>] 99.6	\[ \frac{\frac{\sqrt{\pi \cdot \left(2 \cdot n\right)}}{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\color{blue}{\left(0.5 \cdot k\right)}}}}{\sqrt{k}} \]

   4. Applied egg-rr 99.3%

      \[\leadsto \color{blue}{{\left(\sqrt{k} \cdot {\left(\sqrt{\pi \cdot \left(2 \cdot n\right)}\right)}^{\left(k - 1\right)}\right)}^{-1}} \]
      Proof

      [Start] 99.6	\[ \frac{\frac{\sqrt{\pi \cdot \left(2 \cdot n\right)}}{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 \cdot k\right)}}}{\sqrt{k}} \]
      clear-num [=>] 99.6	\[ \color{blue}{\frac{1}{\frac{\sqrt{k}}{\frac{\sqrt{\pi \cdot \left(2 \cdot n\right)}}{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 \cdot k\right)}}}}} \]
      inv-pow [=>] 99.6	\[ \color{blue}{{\left(\frac{\sqrt{k}}{\frac{\sqrt{\pi \cdot \left(2 \cdot n\right)}}{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 \cdot k\right)}}}\right)}^{-1}} \]
      div-inv [=>] 99.6	\[ {\color{blue}{\left(\sqrt{k} \cdot \frac{1}{\frac{\sqrt{\pi \cdot \left(2 \cdot n\right)}}{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 \cdot k\right)}}}\right)}}^{-1} \]
      clear-num [<=] 99.6	\[ {\left(\sqrt{k} \cdot \color{blue}{\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 \cdot k\right)}}{\sqrt{\pi \cdot \left(2 \cdot n\right)}}}\right)}^{-1} \]
      pow-unpow [=>] 99.6	\[ {\left(\sqrt{k} \cdot \frac{\color{blue}{{\left({\left(\pi \cdot \left(2 \cdot n\right)\right)}^{0.5}\right)}^{k}}}{\sqrt{\pi \cdot \left(2 \cdot n\right)}}\right)}^{-1} \]
      pow1/2 [<=] 99.6	\[ {\left(\sqrt{k} \cdot \frac{{\color{blue}{\left(\sqrt{\pi \cdot \left(2 \cdot n\right)}\right)}}^{k}}{\sqrt{\pi \cdot \left(2 \cdot n\right)}}\right)}^{-1} \]
      pow1 [=>] 99.6	\[ {\left(\sqrt{k} \cdot \frac{{\left(\sqrt{\pi \cdot \left(2 \cdot n\right)}\right)}^{k}}{\color{blue}{{\left(\sqrt{\pi \cdot \left(2 \cdot n\right)}\right)}^{1}}}\right)}^{-1} \]
      pow-div [=>] 99.3	\[ {\left(\sqrt{k} \cdot \color{blue}{{\left(\sqrt{\pi \cdot \left(2 \cdot n\right)}\right)}^{\left(k - 1\right)}}\right)}^{-1} \]

   5. Simplified 99.3%

      \[\leadsto \color{blue}{\frac{1}{\sqrt{k} \cdot {\left(\sqrt{n \cdot \left(2 \cdot \pi\right)}\right)}^{\left(k + -1\right)}}} \]
      Proof

      [Start] 99.3	\[ {\left(\sqrt{k} \cdot {\left(\sqrt{\pi \cdot \left(2 \cdot n\right)}\right)}^{\left(k - 1\right)}\right)}^{-1} \]
      unpow-1 [=>] 99.3	\[ \color{blue}{\frac{1}{\sqrt{k} \cdot {\left(\sqrt{\pi \cdot \left(2 \cdot n\right)}\right)}^{\left(k - 1\right)}}} \]
      associate-*r* [=>] 99.3	\[ \frac{1}{\sqrt{k} \cdot {\left(\sqrt{\color{blue}{\left(\pi \cdot 2\right) \cdot n}}\right)}^{\left(k - 1\right)}} \]
      *-commutative [=>] 99.3	\[ \frac{1}{\sqrt{k} \cdot {\left(\sqrt{\color{blue}{n \cdot \left(\pi \cdot 2\right)}}\right)}^{\left(k - 1\right)}} \]
      *-commutative [=>] 99.3	\[ \frac{1}{\sqrt{k} \cdot {\left(\sqrt{n \cdot \color{blue}{\left(2 \cdot \pi\right)}}\right)}^{\left(k - 1\right)}} \]
      sub-neg [=>] 99.3	\[ \frac{1}{\sqrt{k} \cdot {\left(\sqrt{n \cdot \left(2 \cdot \pi\right)}\right)}^{\color{blue}{\left(k + \left(-1\right)\right)}}} \]
      metadata-eval [=>] 99.3	\[ \frac{1}{\sqrt{k} \cdot {\left(\sqrt{n \cdot \left(2 \cdot \pi\right)}\right)}^{\left(k + \color{blue}{-1}\right)}} \]

   6. Applied egg-rr 95.1%

      \[\leadsto \frac{1}{\color{blue}{e^{\mathsf{log1p}\left(\sqrt{k \cdot {\left(n \cdot \left(2 \cdot \pi\right)\right)}^{\left(k + -1\right)}}\right)} - 1}} \]
      Proof

      [Start] 99.3	\[ \frac{1}{\sqrt{k} \cdot {\left(\sqrt{n \cdot \left(2 \cdot \pi\right)}\right)}^{\left(k + -1\right)}} \]
      expm1-log1p-u [=>] 99.3	\[ \frac{1}{\color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\sqrt{k} \cdot {\left(\sqrt{n \cdot \left(2 \cdot \pi\right)}\right)}^{\left(k + -1\right)}\right)\right)}} \]
      expm1-udef [=>] 95.0	\[ \frac{1}{\color{blue}{e^{\mathsf{log1p}\left(\sqrt{k} \cdot {\left(\sqrt{n \cdot \left(2 \cdot \pi\right)}\right)}^{\left(k + -1\right)}\right)} - 1}} \]

   7. Simplified 99.3%

      \[\leadsto \frac{1}{\color{blue}{\sqrt{k \cdot {\left(n \cdot \left(2 \cdot \pi\right)\right)}^{\left(k + -1\right)}}}} \]
      Proof

      [Start] 95.1	\[ \frac{1}{e^{\mathsf{log1p}\left(\sqrt{k \cdot {\left(n \cdot \left(2 \cdot \pi\right)\right)}^{\left(k + -1\right)}}\right)} - 1} \]
      expm1-def [=>] 99.2	\[ \frac{1}{\color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\sqrt{k \cdot {\left(n \cdot \left(2 \cdot \pi\right)\right)}^{\left(k + -1\right)}}\right)\right)}} \]
      expm1-log1p [=>] 99.3	\[ \frac{1}{\color{blue}{\sqrt{k \cdot {\left(n \cdot \left(2 \cdot \pi\right)\right)}^{\left(k + -1\right)}}}} \]

3. Recombined 2 regimes into one program.

4. Final simplification 99.3%

   \[\leadsto \begin{array}{l} \mathbf{if}\;k \leq 7.2 \cdot 10^{-17}:\\ \;\;\;\;\sqrt{\frac{\pi}{k}} \cdot \sqrt{2 \cdot n}\\ \mathbf{else}:\\ \;\;\;\;\frac{1}{\sqrt{k \cdot {\left(n \cdot \left(\pi \cdot 2\right)\right)}^{\left(k + -1\right)}}}\\ \end{array} \]

Alternatives

Alternative 1
Accuracy	99.4%
Cost	32896

\[\begin{array}{l} t_0 := \pi \cdot \left(2 \cdot n\right)\\ \frac{\frac{\sqrt{t_0}}{{t_0}^{\left(0.5 \cdot k\right)}}}{\sqrt{k}} \end{array} \]

Alternative 2
Accuracy	99.1%
Cost	26624

\[\begin{array}{l} t_0 := 0.5 + k \cdot -0.5\\ \frac{{\left(2 \cdot n\right)}^{t_0} \cdot {\pi}^{t_0}}{\sqrt{k}} \end{array} \]

Alternative 3
Accuracy	99.2%
Cost	19908

\[\begin{array}{l} \mathbf{if}\;k \leq 7 \cdot 10^{-22}:\\ \;\;\;\;\sqrt{\frac{\pi}{k}} \cdot \sqrt{2 \cdot n}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{\frac{{\left(n \cdot \left(\pi \cdot 2\right)\right)}^{\left(1 - k\right)}}{k}}\\ \end{array} \]

Alternative 4
Accuracy	99.3%
Cost	19904

\[\frac{{\left(\pi \cdot \left(2 \cdot n\right)\right)}^{\left(0.5 - \frac{k}{2}\right)}}{\sqrt{k}} \]

Alternative 5
Accuracy	65.5%
Cost	19584

\[\sqrt{\frac{\pi}{k}} \cdot \sqrt{2 \cdot n} \]

Alternative 6
Accuracy	48.9%
Cost	13184

\[\sqrt{2 \cdot \left(n \cdot \frac{\pi}{k}\right)} \]

Alternative 7
Accuracy	48.9%
Cost	13184

\[\sqrt{2 \cdot \left(\pi \cdot \frac{n}{k}\right)} \]

Reproduce

herbie shell --seed 2023126 
(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))))