Migdal et al, Equation (51)

Percentage Accurate: 99.4% → 99.5%
Time: 5.8s
Alternatives: 6
Speedup: 1.1×

Specification

?
\[\begin{array}{l} \\ \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \end{array} \]
(FPCore (k n)
 :precision binary64
 (* (/ 1.0 (sqrt k)) (pow (* (* 2.0 PI) n) (/ (- 1.0 k) 2.0))))
double code(double k, double n) {
	return (1.0 / sqrt(k)) * pow(((2.0 * ((double) M_PI)) * n), ((1.0 - k) / 2.0));
}
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));
}
def code(k, n):
	return (1.0 / math.sqrt(k)) * math.pow(((2.0 * math.pi) * n), ((1.0 - k) / 2.0))
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 tmp = code(k, n)
	tmp = (1.0 / sqrt(k)) * (((2.0 * pi) * n) ^ ((1.0 - k) / 2.0));
end
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]
\begin{array}{l}

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

Sampling outcomes in binary64 precision:

Local Percentage Accuracy vs ?

The average percentage accuracy by input value. Horizontal axis shows value of an input variable; the variable is choosen in the title. Vertical axis is accuracy; higher is better. Red represent the original program, while blue represents Herbie's suggestion. These can be toggled with buttons below the plot. The line is an average while dots represent individual samples.

Accuracy vs Speed?

Herbie found 6 alternatives:

AlternativeAccuracySpeedup
The accuracy (vertical axis) and speed (horizontal axis) of each alternatives. Up and to the right is better. The red square shows the initial program, and each blue circle shows an alternative.The line shows the best available speed-accuracy tradeoffs.

Initial Program: 99.4% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \end{array} \]
(FPCore (k n)
 :precision binary64
 (* (/ 1.0 (sqrt k)) (pow (* (* 2.0 PI) n) (/ (- 1.0 k) 2.0))))
double code(double k, double n) {
	return (1.0 / sqrt(k)) * pow(((2.0 * ((double) M_PI)) * n), ((1.0 - k) / 2.0));
}
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));
}
def code(k, n):
	return (1.0 / math.sqrt(k)) * math.pow(((2.0 * math.pi) * n), ((1.0 - k) / 2.0))
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 tmp = code(k, n)
	tmp = (1.0 / sqrt(k)) * (((2.0 * pi) * n) ^ ((1.0 - k) / 2.0));
end
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]
\begin{array}{l}

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

Alternative 1: 99.5% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{{\left(\left(\pi \cdot 2\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}} \end{array} \]
(FPCore (k n)
 :precision binary64
 (/ (pow (* (* PI 2.0) n) (/ (- 1.0 k) 2.0)) (sqrt k)))
double code(double k, double n) {
	return pow(((((double) M_PI) * 2.0) * n), ((1.0 - k) / 2.0)) / sqrt(k);
}
public static double code(double k, double n) {
	return Math.pow(((Math.PI * 2.0) * n), ((1.0 - k) / 2.0)) / Math.sqrt(k);
}
def code(k, n):
	return math.pow(((math.pi * 2.0) * n), ((1.0 - k) / 2.0)) / math.sqrt(k)
function code(k, n)
	return Float64((Float64(Float64(pi * 2.0) * n) ^ Float64(Float64(1.0 - k) / 2.0)) / sqrt(k))
end
function tmp = code(k, n)
	tmp = (((pi * 2.0) * n) ^ ((1.0 - k) / 2.0)) / sqrt(k);
end
code[k_, n_] := N[(N[Power[N[(N[(Pi * 2.0), $MachinePrecision] * n), $MachinePrecision], N[(N[(1.0 - k), $MachinePrecision] / 2.0), $MachinePrecision]], $MachinePrecision] / N[Sqrt[k], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{{\left(\left(\pi \cdot 2\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}}
\end{array}
Derivation
  1. Initial program 99.5%

    \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-*.f64N/A

      \[\leadsto \color{blue}{\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}} \]
    2. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{1}{\sqrt{k}}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
    3. lift-sqrt.f64N/A

      \[\leadsto \frac{1}{\color{blue}{\sqrt{k}}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
    4. lift-pow.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot \color{blue}{{\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}} \]
    5. lift-*.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\color{blue}{\left(\left(2 \cdot \pi\right) \cdot n\right)}}^{\left(\frac{1 - k}{2}\right)} \]
    6. lift-PI.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \color{blue}{\mathsf{PI}\left(\right)}\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
    7. lift-*.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\color{blue}{\left(2 \cdot \mathsf{PI}\left(\right)\right)} \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
    8. lift--.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{\color{blue}{1 - k}}{2}\right)} \]
    9. lift-/.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\color{blue}{\left(\frac{1 - k}{2}\right)}} \]
    10. associate-*l/N/A

      \[\leadsto \color{blue}{\frac{1 \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}}} \]
    11. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{1 \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}}} \]
  4. Applied rewrites99.6%

    \[\leadsto \color{blue}{\frac{1 \cdot {\left(\left(\pi \cdot 2\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}}} \]
  5. Final simplification99.6%

    \[\leadsto \frac{{\left(\left(\pi \cdot 2\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}} \]
  6. Add Preprocessing

Alternative 2: 49.8% accurate, 0.8× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 5 \cdot 10^{+130}:\\ \;\;\;\;\sqrt{\pi \cdot \left(\frac{n}{k} \cdot 2\right)}\\ \mathbf{else}:\\ \;\;\;\;\frac{\sqrt{\left(k + k\right) \cdot \left(\pi \cdot n\right)}}{k}\\ \end{array} \end{array} \]
(FPCore (k n)
 :precision binary64
 (if (<= (* (/ 1.0 (sqrt k)) (pow (* (* 2.0 PI) n) (/ (- 1.0 k) 2.0))) 5e+130)
   (sqrt (* PI (* (/ n k) 2.0)))
   (/ (sqrt (* (+ k k) (* PI n))) k)))
double code(double k, double n) {
	double tmp;
	if (((1.0 / sqrt(k)) * pow(((2.0 * ((double) M_PI)) * n), ((1.0 - k) / 2.0))) <= 5e+130) {
		tmp = sqrt((((double) M_PI) * ((n / k) * 2.0)));
	} else {
		tmp = sqrt(((k + k) * (((double) M_PI) * n))) / k;
	}
	return tmp;
}
public static double code(double k, double n) {
	double tmp;
	if (((1.0 / Math.sqrt(k)) * Math.pow(((2.0 * Math.PI) * n), ((1.0 - k) / 2.0))) <= 5e+130) {
		tmp = Math.sqrt((Math.PI * ((n / k) * 2.0)));
	} else {
		tmp = Math.sqrt(((k + k) * (Math.PI * n))) / k;
	}
	return tmp;
}
def code(k, n):
	tmp = 0
	if ((1.0 / math.sqrt(k)) * math.pow(((2.0 * math.pi) * n), ((1.0 - k) / 2.0))) <= 5e+130:
		tmp = math.sqrt((math.pi * ((n / k) * 2.0)))
	else:
		tmp = math.sqrt(((k + k) * (math.pi * n))) / k
	return tmp
function code(k, n)
	tmp = 0.0
	if (Float64(Float64(1.0 / sqrt(k)) * (Float64(Float64(2.0 * pi) * n) ^ Float64(Float64(1.0 - k) / 2.0))) <= 5e+130)
		tmp = sqrt(Float64(pi * Float64(Float64(n / k) * 2.0)));
	else
		tmp = Float64(sqrt(Float64(Float64(k + k) * Float64(pi * n))) / k);
	end
	return tmp
end
function tmp_2 = code(k, n)
	tmp = 0.0;
	if (((1.0 / sqrt(k)) * (((2.0 * pi) * n) ^ ((1.0 - k) / 2.0))) <= 5e+130)
		tmp = sqrt((pi * ((n / k) * 2.0)));
	else
		tmp = sqrt(((k + k) * (pi * n))) / k;
	end
	tmp_2 = tmp;
end
code[k_, n_] := If[LessEqual[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], 5e+130], N[Sqrt[N[(Pi * N[(N[(n / k), $MachinePrecision] * 2.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision], N[(N[Sqrt[N[(N[(k + k), $MachinePrecision] * N[(Pi * n), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / k), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 5 \cdot 10^{+130}:\\
\;\;\;\;\sqrt{\pi \cdot \left(\frac{n}{k} \cdot 2\right)}\\

\mathbf{else}:\\
\;\;\;\;\frac{\sqrt{\left(k + k\right) \cdot \left(\pi \cdot n\right)}}{k}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (*.f64 (/.f64 #s(literal 1 binary64) (sqrt.f64 k)) (pow.f64 (*.f64 (*.f64 #s(literal 2 binary64) (PI.f64)) n) (/.f64 (-.f64 #s(literal 1 binary64) k) #s(literal 2 binary64)))) < 4.9999999999999996e130

    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. Add Preprocessing
    3. Taylor expanded in k around 0

      \[\leadsto \color{blue}{\sqrt{\frac{n \cdot \mathsf{PI}\left(\right)}{k}} \cdot \sqrt{2}} \]
    4. Step-by-step derivation
      1. sqrt-unprodN/A

        \[\leadsto \sqrt{\frac{n \cdot \mathsf{PI}\left(\right)}{k} \cdot 2} \]
      2. lower-sqrt.f64N/A

        \[\leadsto \sqrt{\frac{n \cdot \mathsf{PI}\left(\right)}{k} \cdot 2} \]
      3. lower-*.f64N/A

        \[\leadsto \sqrt{\frac{n \cdot \mathsf{PI}\left(\right)}{k} \cdot 2} \]
      4. lower-/.f64N/A

        \[\leadsto \sqrt{\frac{n \cdot \mathsf{PI}\left(\right)}{k} \cdot 2} \]
      5. *-commutativeN/A

        \[\leadsto \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2} \]
      6. lower-*.f64N/A

        \[\leadsto \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2} \]
      7. lift-PI.f6454.5

        \[\leadsto \sqrt{\frac{\pi \cdot n}{k} \cdot 2} \]
    5. Applied rewrites54.5%

      \[\leadsto \color{blue}{\sqrt{\frac{\pi \cdot n}{k} \cdot 2}} \]
    6. Step-by-step derivation
      1. lift-/.f64N/A

        \[\leadsto \sqrt{\frac{\pi \cdot n}{k} \cdot 2} \]
      2. lift-PI.f64N/A

        \[\leadsto \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2} \]
      3. lift-*.f64N/A

        \[\leadsto \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2} \]
      4. associate-/l*N/A

        \[\leadsto \sqrt{\left(\mathsf{PI}\left(\right) \cdot \frac{n}{k}\right) \cdot 2} \]
      5. lower-*.f64N/A

        \[\leadsto \sqrt{\left(\mathsf{PI}\left(\right) \cdot \frac{n}{k}\right) \cdot 2} \]
      6. lift-PI.f64N/A

        \[\leadsto \sqrt{\left(\pi \cdot \frac{n}{k}\right) \cdot 2} \]
      7. lower-/.f6454.5

        \[\leadsto \sqrt{\left(\pi \cdot \frac{n}{k}\right) \cdot 2} \]
    7. Applied rewrites54.5%

      \[\leadsto \sqrt{\left(\pi \cdot \frac{n}{k}\right) \cdot 2} \]
    8. Step-by-step derivation
      1. lift-*.f64N/A

        \[\leadsto \sqrt{\left(\pi \cdot \frac{n}{k}\right) \cdot 2} \]
      2. lift-PI.f64N/A

        \[\leadsto \sqrt{\left(\mathsf{PI}\left(\right) \cdot \frac{n}{k}\right) \cdot 2} \]
      3. lift-*.f64N/A

        \[\leadsto \sqrt{\left(\mathsf{PI}\left(\right) \cdot \frac{n}{k}\right) \cdot 2} \]
      4. associate-*l*N/A

        \[\leadsto \sqrt{\mathsf{PI}\left(\right) \cdot \left(\frac{n}{k} \cdot 2\right)} \]
      5. lower-*.f64N/A

        \[\leadsto \sqrt{\mathsf{PI}\left(\right) \cdot \left(\frac{n}{k} \cdot 2\right)} \]
      6. lift-PI.f64N/A

        \[\leadsto \sqrt{\pi \cdot \left(\frac{n}{k} \cdot 2\right)} \]
      7. lower-*.f6454.5

        \[\leadsto \sqrt{\pi \cdot \left(\frac{n}{k} \cdot 2\right)} \]
    9. Applied rewrites54.5%

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

    if 4.9999999999999996e130 < (*.f64 (/.f64 #s(literal 1 binary64) (sqrt.f64 k)) (pow.f64 (*.f64 (*.f64 #s(literal 2 binary64) (PI.f64)) n) (/.f64 (-.f64 #s(literal 1 binary64) k) #s(literal 2 binary64))))

    1. Initial program 99.7%

      \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
    2. Add Preprocessing
    3. Taylor expanded in k around 0

      \[\leadsto \color{blue}{\frac{\frac{-1}{2} \cdot \left(\sqrt{{k}^{3} \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)} \cdot \left(\log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \sqrt{2}\right)\right) + \sqrt{k \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)} \cdot \sqrt{2}}{k}} \]
    4. Step-by-step derivation
      1. lower-/.f64N/A

        \[\leadsto \frac{\frac{-1}{2} \cdot \left(\sqrt{{k}^{3} \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)} \cdot \left(\log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \sqrt{2}\right)\right) + \sqrt{k \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)} \cdot \sqrt{2}}{\color{blue}{k}} \]
    5. Applied rewrites78.6%

      \[\leadsto \color{blue}{\frac{\sqrt{\left(\left(\pi \cdot n\right) \cdot k\right) \cdot 2} + \left(\left(\log \left(\left(\pi \cdot 2\right) \cdot n\right) \cdot \sqrt{2}\right) \cdot \sqrt{\left({k}^{3} \cdot n\right) \cdot \pi}\right) \cdot -0.5}{k}} \]
    6. Taylor expanded in k around 0

      \[\leadsto \frac{\sqrt{k \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)} \cdot \sqrt{2}}{k} \]
    7. Step-by-step derivation
      1. *-commutativeN/A

        \[\leadsto \frac{\sqrt{k \cdot \left(\mathsf{PI}\left(\right) \cdot n\right)} \cdot \sqrt{2}}{k} \]
      2. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{k \cdot \left(\mathsf{PI}\left(\right) \cdot n\right)} \cdot \sqrt{2}}{k} \]
      3. lift-PI.f64N/A

        \[\leadsto \frac{\sqrt{k \cdot \left(\pi \cdot n\right)} \cdot \sqrt{2}}{k} \]
      4. *-commutativeN/A

        \[\leadsto \frac{\sqrt{\left(\pi \cdot n\right) \cdot k} \cdot \sqrt{2}}{k} \]
      5. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{\left(\pi \cdot n\right) \cdot k} \cdot \sqrt{2}}{k} \]
      6. sqrt-prodN/A

        \[\leadsto \frac{\sqrt{\left(\left(\pi \cdot n\right) \cdot k\right) \cdot 2}}{k} \]
      7. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{\left(\left(\pi \cdot n\right) \cdot k\right) \cdot 2}}{k} \]
      8. lift-sqrt.f6444.9

        \[\leadsto \frac{\sqrt{\left(\left(\pi \cdot n\right) \cdot k\right) \cdot 2}}{k} \]
      9. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{\left(\left(\pi \cdot n\right) \cdot k\right) \cdot 2}}{k} \]
      10. *-commutativeN/A

        \[\leadsto \frac{\sqrt{2 \cdot \left(\left(\pi \cdot n\right) \cdot k\right)}}{k} \]
      11. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{2 \cdot \left(\left(\pi \cdot n\right) \cdot k\right)}}{k} \]
      12. *-commutativeN/A

        \[\leadsto \frac{\sqrt{2 \cdot \left(k \cdot \left(\pi \cdot n\right)\right)}}{k} \]
      13. lift-PI.f64N/A

        \[\leadsto \frac{\sqrt{2 \cdot \left(k \cdot \left(\mathsf{PI}\left(\right) \cdot n\right)\right)}}{k} \]
      14. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{2 \cdot \left(k \cdot \left(\mathsf{PI}\left(\right) \cdot n\right)\right)}}{k} \]
      15. *-commutativeN/A

        \[\leadsto \frac{\sqrt{2 \cdot \left(k \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right)}}{k} \]
      16. associate-*r*N/A

        \[\leadsto \frac{\sqrt{\left(2 \cdot k\right) \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)}}{k} \]
    8. Applied rewrites44.9%

      \[\leadsto \frac{\sqrt{\left(2 \cdot k\right) \cdot \left(\pi \cdot n\right)}}{k} \]
    9. Step-by-step derivation
      1. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{\left(2 \cdot k\right) \cdot \left(\pi \cdot n\right)}}{k} \]
      2. count-2-revN/A

        \[\leadsto \frac{\sqrt{\left(k + k\right) \cdot \left(\pi \cdot n\right)}}{k} \]
      3. lower-+.f6444.9

        \[\leadsto \frac{\sqrt{\left(k + k\right) \cdot \left(\pi \cdot n\right)}}{k} \]
    10. Applied rewrites44.9%

      \[\leadsto \frac{\sqrt{\left(k + k\right) \cdot \left(\pi \cdot n\right)}}{k} \]
  3. Recombined 2 regimes into one program.
  4. Add Preprocessing

Alternative 3: 98.2% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;k \leq 1:\\ \;\;\;\;\frac{\sqrt{\left(n + n\right) \cdot \pi}}{\sqrt{k}}\\ \mathbf{else}:\\ \;\;\;\;\frac{1}{\sqrt{k}} \cdot {\left(\left(\pi + \pi\right) \cdot n\right)}^{\left(-0.5 \cdot k\right)}\\ \end{array} \end{array} \]
(FPCore (k n)
 :precision binary64
 (if (<= k 1.0)
   (/ (sqrt (* (+ n n) PI)) (sqrt k))
   (* (/ 1.0 (sqrt k)) (pow (* (+ PI PI) n) (* -0.5 k)))))
double code(double k, double n) {
	double tmp;
	if (k <= 1.0) {
		tmp = sqrt(((n + n) * ((double) M_PI))) / sqrt(k);
	} else {
		tmp = (1.0 / sqrt(k)) * pow(((((double) M_PI) + ((double) M_PI)) * n), (-0.5 * k));
	}
	return tmp;
}
public static double code(double k, double n) {
	double tmp;
	if (k <= 1.0) {
		tmp = Math.sqrt(((n + n) * Math.PI)) / Math.sqrt(k);
	} else {
		tmp = (1.0 / Math.sqrt(k)) * Math.pow(((Math.PI + Math.PI) * n), (-0.5 * k));
	}
	return tmp;
}
def code(k, n):
	tmp = 0
	if k <= 1.0:
		tmp = math.sqrt(((n + n) * math.pi)) / math.sqrt(k)
	else:
		tmp = (1.0 / math.sqrt(k)) * math.pow(((math.pi + math.pi) * n), (-0.5 * k))
	return tmp
function code(k, n)
	tmp = 0.0
	if (k <= 1.0)
		tmp = Float64(sqrt(Float64(Float64(n + n) * pi)) / sqrt(k));
	else
		tmp = Float64(Float64(1.0 / sqrt(k)) * (Float64(Float64(pi + pi) * n) ^ Float64(-0.5 * k)));
	end
	return tmp
end
function tmp_2 = code(k, n)
	tmp = 0.0;
	if (k <= 1.0)
		tmp = sqrt(((n + n) * pi)) / sqrt(k);
	else
		tmp = (1.0 / sqrt(k)) * (((pi + pi) * n) ^ (-0.5 * k));
	end
	tmp_2 = tmp;
end
code[k_, n_] := If[LessEqual[k, 1.0], N[(N[Sqrt[N[(N[(n + n), $MachinePrecision] * Pi), $MachinePrecision]], $MachinePrecision] / N[Sqrt[k], $MachinePrecision]), $MachinePrecision], N[(N[(1.0 / N[Sqrt[k], $MachinePrecision]), $MachinePrecision] * N[Power[N[(N[(Pi + Pi), $MachinePrecision] * n), $MachinePrecision], N[(-0.5 * k), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;k \leq 1:\\
\;\;\;\;\frac{\sqrt{\left(n + n\right) \cdot \pi}}{\sqrt{k}}\\

\mathbf{else}:\\
\;\;\;\;\frac{1}{\sqrt{k}} \cdot {\left(\left(\pi + \pi\right) \cdot n\right)}^{\left(-0.5 \cdot k\right)}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if k < 1

    1. Initial program 99.0%

      \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
    2. Add Preprocessing
    3. Step-by-step derivation
      1. lift-*.f64N/A

        \[\leadsto \color{blue}{\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}} \]
      2. lift-/.f64N/A

        \[\leadsto \color{blue}{\frac{1}{\sqrt{k}}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
      3. lift-sqrt.f64N/A

        \[\leadsto \frac{1}{\color{blue}{\sqrt{k}}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
      4. lift-pow.f64N/A

        \[\leadsto \frac{1}{\sqrt{k}} \cdot \color{blue}{{\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}} \]
      5. lift-*.f64N/A

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\color{blue}{\left(\left(2 \cdot \pi\right) \cdot n\right)}}^{\left(\frac{1 - k}{2}\right)} \]
      6. lift-PI.f64N/A

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \color{blue}{\mathsf{PI}\left(\right)}\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
      7. lift-*.f64N/A

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\color{blue}{\left(2 \cdot \mathsf{PI}\left(\right)\right)} \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
      8. lift--.f64N/A

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{\color{blue}{1 - k}}{2}\right)} \]
      9. lift-/.f64N/A

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\color{blue}{\left(\frac{1 - k}{2}\right)}} \]
      10. associate-*l/N/A

        \[\leadsto \color{blue}{\frac{1 \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}}} \]
      11. lower-/.f64N/A

        \[\leadsto \color{blue}{\frac{1 \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}}} \]
    4. Applied rewrites99.2%

      \[\leadsto \color{blue}{\frac{1 \cdot {\left(\left(\pi \cdot 2\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}}} \]
    5. Taylor expanded in k around 0

      \[\leadsto \frac{\color{blue}{\sqrt{n \cdot \mathsf{PI}\left(\right)} \cdot \sqrt{2}}}{\sqrt{k}} \]
    6. Step-by-step derivation
      1. sqrt-unprodN/A

        \[\leadsto \frac{\sqrt{\left(n \cdot \mathsf{PI}\left(\right)\right) \cdot 2}}{\sqrt{k}} \]
      2. *-commutativeN/A

        \[\leadsto \frac{\sqrt{\left(\mathsf{PI}\left(\right) \cdot n\right) \cdot 2}}{\sqrt{k}} \]
      3. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{\left(\mathsf{PI}\left(\right) \cdot n\right) \cdot 2}}{\sqrt{k}} \]
      4. lift-PI.f64N/A

        \[\leadsto \frac{\sqrt{\left(\pi \cdot n\right) \cdot 2}}{\sqrt{k}} \]
      5. *-commutativeN/A

        \[\leadsto \frac{\sqrt{2 \cdot \left(\pi \cdot n\right)}}{\sqrt{k}} \]
      6. lift-PI.f64N/A

        \[\leadsto \frac{\sqrt{2 \cdot \left(\mathsf{PI}\left(\right) \cdot n\right)}}{\sqrt{k}} \]
      7. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{2 \cdot \left(\mathsf{PI}\left(\right) \cdot n\right)}}{\sqrt{k}} \]
      8. associate-*l*N/A

        \[\leadsto \frac{\sqrt{\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n}}{\sqrt{k}} \]
      9. *-commutativeN/A

        \[\leadsto \frac{\sqrt{\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot n}}{\sqrt{k}} \]
      10. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot n}}{\sqrt{k}} \]
      11. lift-PI.f64N/A

        \[\leadsto \frac{\sqrt{\left(\pi \cdot 2\right) \cdot n}}{\sqrt{k}} \]
      12. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{\left(\pi \cdot 2\right) \cdot n}}{\sqrt{k}} \]
      13. lift-sqrt.f6496.6

        \[\leadsto \frac{\sqrt{\left(\pi \cdot 2\right) \cdot n}}{\sqrt{k}} \]
      14. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{\left(\pi \cdot 2\right) \cdot n}}{\sqrt{k}} \]
      15. lift-PI.f64N/A

        \[\leadsto \frac{\sqrt{\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot n}}{\sqrt{k}} \]
      16. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot n}}{\sqrt{k}} \]
      17. *-commutativeN/A

        \[\leadsto \frac{\sqrt{\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n}}{\sqrt{k}} \]
      18. associate-*l*N/A

        \[\leadsto \frac{\sqrt{2 \cdot \left(\mathsf{PI}\left(\right) \cdot n\right)}}{\sqrt{k}} \]
      19. *-commutativeN/A

        \[\leadsto \frac{\sqrt{2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)}}{\sqrt{k}} \]
      20. associate-*r*N/A

        \[\leadsto \frac{\sqrt{\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)}}{\sqrt{k}} \]
      21. lower-*.f64N/A

        \[\leadsto \frac{\sqrt{\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)}}{\sqrt{k}} \]
      22. lower-*.f64N/A

        \[\leadsto \frac{\sqrt{\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)}}{\sqrt{k}} \]
    7. Applied rewrites96.6%

      \[\leadsto \frac{\color{blue}{\sqrt{\left(2 \cdot n\right) \cdot \pi}}}{\sqrt{k}} \]
    8. Step-by-step derivation
      1. lift-*.f64N/A

        \[\leadsto \frac{\sqrt{\left(2 \cdot n\right) \cdot \pi}}{\sqrt{k}} \]
      2. count-2-revN/A

        \[\leadsto \frac{\sqrt{\left(n + n\right) \cdot \pi}}{\sqrt{k}} \]
      3. lower-+.f6496.6

        \[\leadsto \frac{\sqrt{\left(n + n\right) \cdot \pi}}{\sqrt{k}} \]
    9. Applied rewrites96.6%

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

    if 1 < k

    1. Initial program 100.0%

      \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
    2. Add Preprocessing
    3. Taylor expanded in k around 0

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\color{blue}{\left(\frac{1}{2} + \frac{-1}{2} \cdot k\right)}} \]
    4. Step-by-step derivation
      1. +-commutativeN/A

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \color{blue}{\frac{1}{2}}\right)} \]
      2. lower-+.f64N/A

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \color{blue}{\frac{1}{2}}\right)} \]
      3. lower-*.f64100.0

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(-0.5 \cdot k + 0.5\right)} \]
    5. Applied rewrites100.0%

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\color{blue}{\left(-0.5 \cdot k + 0.5\right)}} \]
    6. Step-by-step derivation
      1. lift-PI.f64N/A

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \color{blue}{\mathsf{PI}\left(\right)}\right) \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \frac{1}{2}\right)} \]
      2. lift-*.f64N/A

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\color{blue}{\left(2 \cdot \mathsf{PI}\left(\right)\right)} \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \frac{1}{2}\right)} \]
      3. count-2-revN/A

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\color{blue}{\left(\mathsf{PI}\left(\right) + \mathsf{PI}\left(\right)\right)} \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \frac{1}{2}\right)} \]
      4. lift-+.f64N/A

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\color{blue}{\left(\mathsf{PI}\left(\right) + \mathsf{PI}\left(\right)\right)} \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \frac{1}{2}\right)} \]
      5. lift-PI.f64N/A

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(\color{blue}{\pi} + \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \frac{1}{2}\right)} \]
      6. lift-PI.f64100.0

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(\pi + \color{blue}{\pi}\right) \cdot n\right)}^{\left(-0.5 \cdot k + 0.5\right)} \]
    7. Applied rewrites100.0%

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\color{blue}{\left(\pi + \pi\right)} \cdot n\right)}^{\left(-0.5 \cdot k + 0.5\right)} \]
    8. Taylor expanded in k around inf

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(\pi + \pi\right) \cdot n\right)}^{\color{blue}{\left(\frac{-1}{2} \cdot k\right)}} \]
    9. Step-by-step derivation
      1. lift-*.f64100.0

        \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(\pi + \pi\right) \cdot n\right)}^{\left(-0.5 \cdot \color{blue}{k}\right)} \]
    10. Applied rewrites100.0%

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(\pi + \pi\right) \cdot n\right)}^{\color{blue}{\left(-0.5 \cdot k\right)}} \]
  3. Recombined 2 regimes into one program.
  4. Add Preprocessing

Alternative 4: 99.4% accurate, 1.1× speedup?

\[\begin{array}{l} \\ \frac{1}{\sqrt{k}} \cdot {\left(\left(\pi + \pi\right) \cdot n\right)}^{\left(-0.5 \cdot k + 0.5\right)} \end{array} \]
(FPCore (k n)
 :precision binary64
 (* (/ 1.0 (sqrt k)) (pow (* (+ PI PI) n) (+ (* -0.5 k) 0.5))))
double code(double k, double n) {
	return (1.0 / sqrt(k)) * pow(((((double) M_PI) + ((double) M_PI)) * n), ((-0.5 * k) + 0.5));
}
public static double code(double k, double n) {
	return (1.0 / Math.sqrt(k)) * Math.pow(((Math.PI + Math.PI) * n), ((-0.5 * k) + 0.5));
}
def code(k, n):
	return (1.0 / math.sqrt(k)) * math.pow(((math.pi + math.pi) * n), ((-0.5 * k) + 0.5))
function code(k, n)
	return Float64(Float64(1.0 / sqrt(k)) * (Float64(Float64(pi + pi) * n) ^ Float64(Float64(-0.5 * k) + 0.5)))
end
function tmp = code(k, n)
	tmp = (1.0 / sqrt(k)) * (((pi + pi) * n) ^ ((-0.5 * k) + 0.5));
end
code[k_, n_] := N[(N[(1.0 / N[Sqrt[k], $MachinePrecision]), $MachinePrecision] * N[Power[N[(N[(Pi + Pi), $MachinePrecision] * n), $MachinePrecision], N[(N[(-0.5 * k), $MachinePrecision] + 0.5), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{1}{\sqrt{k}} \cdot {\left(\left(\pi + \pi\right) \cdot n\right)}^{\left(-0.5 \cdot k + 0.5\right)}
\end{array}
Derivation
  1. Initial program 99.5%

    \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
  2. Add Preprocessing
  3. Taylor expanded in k around 0

    \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\color{blue}{\left(\frac{1}{2} + \frac{-1}{2} \cdot k\right)}} \]
  4. Step-by-step derivation
    1. +-commutativeN/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \color{blue}{\frac{1}{2}}\right)} \]
    2. lower-+.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \color{blue}{\frac{1}{2}}\right)} \]
    3. lower-*.f6499.5

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(-0.5 \cdot k + 0.5\right)} \]
  5. Applied rewrites99.5%

    \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\color{blue}{\left(-0.5 \cdot k + 0.5\right)}} \]
  6. Step-by-step derivation
    1. lift-PI.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \color{blue}{\mathsf{PI}\left(\right)}\right) \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \frac{1}{2}\right)} \]
    2. lift-*.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\color{blue}{\left(2 \cdot \mathsf{PI}\left(\right)\right)} \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \frac{1}{2}\right)} \]
    3. count-2-revN/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\color{blue}{\left(\mathsf{PI}\left(\right) + \mathsf{PI}\left(\right)\right)} \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \frac{1}{2}\right)} \]
    4. lift-+.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\color{blue}{\left(\mathsf{PI}\left(\right) + \mathsf{PI}\left(\right)\right)} \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \frac{1}{2}\right)} \]
    5. lift-PI.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(\color{blue}{\pi} + \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{-1}{2} \cdot k + \frac{1}{2}\right)} \]
    6. lift-PI.f6499.5

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(\pi + \color{blue}{\pi}\right) \cdot n\right)}^{\left(-0.5 \cdot k + 0.5\right)} \]
  7. Applied rewrites99.5%

    \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\color{blue}{\left(\pi + \pi\right)} \cdot n\right)}^{\left(-0.5 \cdot k + 0.5\right)} \]
  8. Add Preprocessing

Alternative 5: 49.8% accurate, 3.8× speedup?

\[\begin{array}{l} \\ \frac{\sqrt{\left(n + n\right) \cdot \pi}}{\sqrt{k}} \end{array} \]
(FPCore (k n) :precision binary64 (/ (sqrt (* (+ n n) PI)) (sqrt k)))
double code(double k, double n) {
	return sqrt(((n + n) * ((double) M_PI))) / sqrt(k);
}
public static double code(double k, double n) {
	return Math.sqrt(((n + n) * Math.PI)) / Math.sqrt(k);
}
def code(k, n):
	return math.sqrt(((n + n) * math.pi)) / math.sqrt(k)
function code(k, n)
	return Float64(sqrt(Float64(Float64(n + n) * pi)) / sqrt(k))
end
function tmp = code(k, n)
	tmp = sqrt(((n + n) * pi)) / sqrt(k);
end
code[k_, n_] := N[(N[Sqrt[N[(N[(n + n), $MachinePrecision] * Pi), $MachinePrecision]], $MachinePrecision] / N[Sqrt[k], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\sqrt{\left(n + n\right) \cdot \pi}}{\sqrt{k}}
\end{array}
Derivation
  1. Initial program 99.5%

    \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-*.f64N/A

      \[\leadsto \color{blue}{\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}} \]
    2. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{1}{\sqrt{k}}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
    3. lift-sqrt.f64N/A

      \[\leadsto \frac{1}{\color{blue}{\sqrt{k}}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
    4. lift-pow.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot \color{blue}{{\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}} \]
    5. lift-*.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\color{blue}{\left(\left(2 \cdot \pi\right) \cdot n\right)}}^{\left(\frac{1 - k}{2}\right)} \]
    6. lift-PI.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \color{blue}{\mathsf{PI}\left(\right)}\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
    7. lift-*.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\color{blue}{\left(2 \cdot \mathsf{PI}\left(\right)\right)} \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
    8. lift--.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{\color{blue}{1 - k}}{2}\right)} \]
    9. lift-/.f64N/A

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\color{blue}{\left(\frac{1 - k}{2}\right)}} \]
    10. associate-*l/N/A

      \[\leadsto \color{blue}{\frac{1 \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}}} \]
    11. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{1 \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}}} \]
  4. Applied rewrites99.6%

    \[\leadsto \color{blue}{\frac{1 \cdot {\left(\left(\pi \cdot 2\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}}{\sqrt{k}}} \]
  5. Taylor expanded in k around 0

    \[\leadsto \frac{\color{blue}{\sqrt{n \cdot \mathsf{PI}\left(\right)} \cdot \sqrt{2}}}{\sqrt{k}} \]
  6. Step-by-step derivation
    1. sqrt-unprodN/A

      \[\leadsto \frac{\sqrt{\left(n \cdot \mathsf{PI}\left(\right)\right) \cdot 2}}{\sqrt{k}} \]
    2. *-commutativeN/A

      \[\leadsto \frac{\sqrt{\left(\mathsf{PI}\left(\right) \cdot n\right) \cdot 2}}{\sqrt{k}} \]
    3. lift-*.f64N/A

      \[\leadsto \frac{\sqrt{\left(\mathsf{PI}\left(\right) \cdot n\right) \cdot 2}}{\sqrt{k}} \]
    4. lift-PI.f64N/A

      \[\leadsto \frac{\sqrt{\left(\pi \cdot n\right) \cdot 2}}{\sqrt{k}} \]
    5. *-commutativeN/A

      \[\leadsto \frac{\sqrt{2 \cdot \left(\pi \cdot n\right)}}{\sqrt{k}} \]
    6. lift-PI.f64N/A

      \[\leadsto \frac{\sqrt{2 \cdot \left(\mathsf{PI}\left(\right) \cdot n\right)}}{\sqrt{k}} \]
    7. lift-*.f64N/A

      \[\leadsto \frac{\sqrt{2 \cdot \left(\mathsf{PI}\left(\right) \cdot n\right)}}{\sqrt{k}} \]
    8. associate-*l*N/A

      \[\leadsto \frac{\sqrt{\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n}}{\sqrt{k}} \]
    9. *-commutativeN/A

      \[\leadsto \frac{\sqrt{\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot n}}{\sqrt{k}} \]
    10. lift-*.f64N/A

      \[\leadsto \frac{\sqrt{\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot n}}{\sqrt{k}} \]
    11. lift-PI.f64N/A

      \[\leadsto \frac{\sqrt{\left(\pi \cdot 2\right) \cdot n}}{\sqrt{k}} \]
    12. lift-*.f64N/A

      \[\leadsto \frac{\sqrt{\left(\pi \cdot 2\right) \cdot n}}{\sqrt{k}} \]
    13. lift-sqrt.f6450.8

      \[\leadsto \frac{\sqrt{\left(\pi \cdot 2\right) \cdot n}}{\sqrt{k}} \]
    14. lift-*.f64N/A

      \[\leadsto \frac{\sqrt{\left(\pi \cdot 2\right) \cdot n}}{\sqrt{k}} \]
    15. lift-PI.f64N/A

      \[\leadsto \frac{\sqrt{\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot n}}{\sqrt{k}} \]
    16. lift-*.f64N/A

      \[\leadsto \frac{\sqrt{\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot n}}{\sqrt{k}} \]
    17. *-commutativeN/A

      \[\leadsto \frac{\sqrt{\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n}}{\sqrt{k}} \]
    18. associate-*l*N/A

      \[\leadsto \frac{\sqrt{2 \cdot \left(\mathsf{PI}\left(\right) \cdot n\right)}}{\sqrt{k}} \]
    19. *-commutativeN/A

      \[\leadsto \frac{\sqrt{2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)}}{\sqrt{k}} \]
    20. associate-*r*N/A

      \[\leadsto \frac{\sqrt{\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)}}{\sqrt{k}} \]
    21. lower-*.f64N/A

      \[\leadsto \frac{\sqrt{\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)}}{\sqrt{k}} \]
    22. lower-*.f64N/A

      \[\leadsto \frac{\sqrt{\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)}}{\sqrt{k}} \]
  7. Applied rewrites50.8%

    \[\leadsto \frac{\color{blue}{\sqrt{\left(2 \cdot n\right) \cdot \pi}}}{\sqrt{k}} \]
  8. Step-by-step derivation
    1. lift-*.f64N/A

      \[\leadsto \frac{\sqrt{\left(2 \cdot n\right) \cdot \pi}}{\sqrt{k}} \]
    2. count-2-revN/A

      \[\leadsto \frac{\sqrt{\left(n + n\right) \cdot \pi}}{\sqrt{k}} \]
    3. lower-+.f6450.8

      \[\leadsto \frac{\sqrt{\left(n + n\right) \cdot \pi}}{\sqrt{k}} \]
  9. Applied rewrites50.8%

    \[\leadsto \frac{\sqrt{\left(n + n\right) \cdot \pi}}{\sqrt{k}} \]
  10. Add Preprocessing

Alternative 6: 38.3% accurate, 4.8× speedup?

\[\begin{array}{l} \\ \sqrt{\pi \cdot \left(\frac{n}{k} \cdot 2\right)} \end{array} \]
(FPCore (k n) :precision binary64 (sqrt (* PI (* (/ n k) 2.0))))
double code(double k, double n) {
	return sqrt((((double) M_PI) * ((n / k) * 2.0)));
}
public static double code(double k, double n) {
	return Math.sqrt((Math.PI * ((n / k) * 2.0)));
}
def code(k, n):
	return math.sqrt((math.pi * ((n / k) * 2.0)))
function code(k, n)
	return sqrt(Float64(pi * Float64(Float64(n / k) * 2.0)))
end
function tmp = code(k, n)
	tmp = sqrt((pi * ((n / k) * 2.0)));
end
code[k_, n_] := N[Sqrt[N[(Pi * N[(N[(n / k), $MachinePrecision] * 2.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\sqrt{\pi \cdot \left(\frac{n}{k} \cdot 2\right)}
\end{array}
Derivation
  1. Initial program 99.5%

    \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
  2. Add Preprocessing
  3. Taylor expanded in k around 0

    \[\leadsto \color{blue}{\sqrt{\frac{n \cdot \mathsf{PI}\left(\right)}{k}} \cdot \sqrt{2}} \]
  4. Step-by-step derivation
    1. sqrt-unprodN/A

      \[\leadsto \sqrt{\frac{n \cdot \mathsf{PI}\left(\right)}{k} \cdot 2} \]
    2. lower-sqrt.f64N/A

      \[\leadsto \sqrt{\frac{n \cdot \mathsf{PI}\left(\right)}{k} \cdot 2} \]
    3. lower-*.f64N/A

      \[\leadsto \sqrt{\frac{n \cdot \mathsf{PI}\left(\right)}{k} \cdot 2} \]
    4. lower-/.f64N/A

      \[\leadsto \sqrt{\frac{n \cdot \mathsf{PI}\left(\right)}{k} \cdot 2} \]
    5. *-commutativeN/A

      \[\leadsto \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2} \]
    6. lower-*.f64N/A

      \[\leadsto \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2} \]
    7. lift-PI.f6437.6

      \[\leadsto \sqrt{\frac{\pi \cdot n}{k} \cdot 2} \]
  5. Applied rewrites37.6%

    \[\leadsto \color{blue}{\sqrt{\frac{\pi \cdot n}{k} \cdot 2}} \]
  6. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \sqrt{\frac{\pi \cdot n}{k} \cdot 2} \]
    2. lift-PI.f64N/A

      \[\leadsto \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2} \]
    3. lift-*.f64N/A

      \[\leadsto \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2} \]
    4. associate-/l*N/A

      \[\leadsto \sqrt{\left(\mathsf{PI}\left(\right) \cdot \frac{n}{k}\right) \cdot 2} \]
    5. lower-*.f64N/A

      \[\leadsto \sqrt{\left(\mathsf{PI}\left(\right) \cdot \frac{n}{k}\right) \cdot 2} \]
    6. lift-PI.f64N/A

      \[\leadsto \sqrt{\left(\pi \cdot \frac{n}{k}\right) \cdot 2} \]
    7. lower-/.f6437.6

      \[\leadsto \sqrt{\left(\pi \cdot \frac{n}{k}\right) \cdot 2} \]
  7. Applied rewrites37.6%

    \[\leadsto \sqrt{\left(\pi \cdot \frac{n}{k}\right) \cdot 2} \]
  8. Step-by-step derivation
    1. lift-*.f64N/A

      \[\leadsto \sqrt{\left(\pi \cdot \frac{n}{k}\right) \cdot 2} \]
    2. lift-PI.f64N/A

      \[\leadsto \sqrt{\left(\mathsf{PI}\left(\right) \cdot \frac{n}{k}\right) \cdot 2} \]
    3. lift-*.f64N/A

      \[\leadsto \sqrt{\left(\mathsf{PI}\left(\right) \cdot \frac{n}{k}\right) \cdot 2} \]
    4. associate-*l*N/A

      \[\leadsto \sqrt{\mathsf{PI}\left(\right) \cdot \left(\frac{n}{k} \cdot 2\right)} \]
    5. lower-*.f64N/A

      \[\leadsto \sqrt{\mathsf{PI}\left(\right) \cdot \left(\frac{n}{k} \cdot 2\right)} \]
    6. lift-PI.f64N/A

      \[\leadsto \sqrt{\pi \cdot \left(\frac{n}{k} \cdot 2\right)} \]
    7. lower-*.f6437.6

      \[\leadsto \sqrt{\pi \cdot \left(\frac{n}{k} \cdot 2\right)} \]
  9. Applied rewrites37.6%

    \[\leadsto \sqrt{\pi \cdot \left(\frac{n}{k} \cdot 2\right)} \]
  10. Add Preprocessing

Reproduce

?
herbie shell --seed 2025065 
(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))))