Migdal et al, Equation (51)

Percentage Accurate: 99.5% → 99.6%
Time: 11.1s
Alternatives: 9
Speedup: 1.1×

Specification

?
\[\begin{array}{l} \\ \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \end{array} \]
(FPCore (k n)
 :precision binary64
 (* (/ 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:

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 9 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: 99.5% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \end{array} \]
(FPCore (k n)
 :precision binary64
 (* (/ 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}

Alternative 1: 99.6% accurate, 0.9× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \mathsf{PI}\left(\right) \cdot \left(n \cdot 2\right)\\ \frac{\sqrt{t\_0}}{{t\_0}^{\left(\frac{k}{2}\right)} \cdot \sqrt{k}} \end{array} \end{array} \]
(FPCore (k n)
 :precision binary64
 (let* ((t_0 (* (PI) (* n 2.0))))
   (/ (sqrt t_0) (* (pow t_0 (/ k 2.0)) (sqrt k)))))
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \mathsf{PI}\left(\right) \cdot \left(n \cdot 2\right)\\
\frac{\sqrt{t\_0}}{{t\_0}^{\left(\frac{k}{2}\right)} \cdot \sqrt{k}}
\end{array}
\end{array}
Derivation
  1. Initial program 99.6%

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

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

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

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

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

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(n \cdot 2\right) \cdot \color{blue}{\mathsf{PI}\left(\right)}\right)}^{\left(\frac{1 - k}{2}\right)} \]
    6. add-sqr-sqrtN/A

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

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

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

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

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

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

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

      \[\leadsto \frac{1}{\sqrt{k}} \cdot {\left(\left(\left(n \cdot 2\right) \cdot \sqrt{\mathsf{PI}\left(\right)}\right) \cdot \sqrt{\color{blue}{\mathsf{PI}\left(\right)}}\right)}^{\left(\frac{1 - k}{2}\right)} \]
    14. lower-sqrt.f6499.4

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

    \[\leadsto \frac{1}{\sqrt{k}} \cdot {\color{blue}{\left(\left(\left(n \cdot 2\right) \cdot \sqrt{\mathsf{PI}\left(\right)}\right) \cdot \sqrt{\mathsf{PI}\left(\right)}\right)}}^{\left(\frac{1 - k}{2}\right)} \]
  5. Applied rewrites99.7%

    \[\leadsto \color{blue}{\frac{\sqrt{\mathsf{PI}\left(\right) \cdot \left(n \cdot 2\right)} \cdot 1}{{\left(\mathsf{PI}\left(\right) \cdot \left(n \cdot 2\right)\right)}^{\left(\frac{k}{2}\right)} \cdot \sqrt{k}}} \]
  6. Final simplification99.7%

    \[\leadsto \frac{\sqrt{\mathsf{PI}\left(\right) \cdot \left(n \cdot 2\right)}}{{\left(\mathsf{PI}\left(\right) \cdot \left(n \cdot 2\right)\right)}^{\left(\frac{k}{2}\right)} \cdot \sqrt{k}} \]
  7. Add Preprocessing

Alternative 2: 73.4% accurate, 0.8× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 0:\\ \;\;\;\;\frac{0}{k}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{\frac{\mathsf{PI}\left(\right)}{k}} \cdot \sqrt{2 \cdot n}\\ \end{array} \end{array} \]
(FPCore (k n)
 :precision binary64
 (if (<= (* (/ 1.0 (sqrt k)) (pow (* (* 2.0 (PI)) n) (/ (- 1.0 k) 2.0))) 0.0)
   (/ 0.0 k)
   (* (sqrt (/ (PI) k)) (sqrt (* 2.0 n)))))
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 0:\\
\;\;\;\;\frac{0}{k}\\

\mathbf{else}:\\
\;\;\;\;\sqrt{\frac{\mathsf{PI}\left(\right)}{k}} \cdot \sqrt{2 \cdot n}\\


\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)))) < 0.0

    1. Initial program 100.0%

      \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
    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. *-commutativeN/A

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

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

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

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

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

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

        \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right) \cdot n}}{k}} \]
      8. lower-PI.f643.2

        \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right)} \cdot n}{k}} \]
    5. Applied rewrites3.2%

      \[\leadsto \color{blue}{\sqrt{2} \cdot \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}}} \]
    6. Step-by-step derivation
      1. Applied rewrites3.2%

        \[\leadsto \color{blue}{\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}} \]
      2. Step-by-step derivation
        1. Applied rewrites3.2%

          \[\leadsto \sqrt{\left(n \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{2}{k}} \]
        2. Applied rewrites100.0%

          \[\leadsto \color{blue}{\frac{0}{k}} \]

        if 0.0 < (*.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 99.4%

          \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
        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. *-commutativeN/A

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

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

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

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

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

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

            \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right) \cdot n}}{k}} \]
          8. lower-PI.f6443.7

            \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right)} \cdot n}{k}} \]
        5. Applied rewrites43.7%

          \[\leadsto \color{blue}{\sqrt{2} \cdot \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}}} \]
        6. Step-by-step derivation
          1. Applied rewrites43.7%

            \[\leadsto \color{blue}{\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}} \]
          2. Step-by-step derivation
            1. Applied rewrites59.0%

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

          Alternative 3: 73.4% accurate, 0.8× speedup?

          \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 0:\\ \;\;\;\;\frac{0}{k}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{n \cdot \mathsf{PI}\left(\right)} \cdot \sqrt{\frac{2}{k}}\\ \end{array} \end{array} \]
          (FPCore (k n)
           :precision binary64
           (if (<= (* (/ 1.0 (sqrt k)) (pow (* (* 2.0 (PI)) n) (/ (- 1.0 k) 2.0))) 0.0)
             (/ 0.0 k)
             (* (sqrt (* n (PI))) (sqrt (/ 2.0 k)))))
          \begin{array}{l}
          
          \\
          \begin{array}{l}
          \mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 0:\\
          \;\;\;\;\frac{0}{k}\\
          
          \mathbf{else}:\\
          \;\;\;\;\sqrt{n \cdot \mathsf{PI}\left(\right)} \cdot \sqrt{\frac{2}{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)))) < 0.0

            1. Initial program 100.0%

              \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
            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. *-commutativeN/A

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

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

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

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

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

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

                \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right) \cdot n}}{k}} \]
              8. lower-PI.f643.2

                \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right)} \cdot n}{k}} \]
            5. Applied rewrites3.2%

              \[\leadsto \color{blue}{\sqrt{2} \cdot \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}}} \]
            6. Step-by-step derivation
              1. Applied rewrites3.2%

                \[\leadsto \color{blue}{\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}} \]
              2. Step-by-step derivation
                1. Applied rewrites3.2%

                  \[\leadsto \sqrt{\left(n \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{2}{k}} \]
                2. Applied rewrites100.0%

                  \[\leadsto \color{blue}{\frac{0}{k}} \]

                if 0.0 < (*.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 99.4%

                  \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
                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. *-commutativeN/A

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

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

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

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

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

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

                    \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right) \cdot n}}{k}} \]
                  8. lower-PI.f6443.7

                    \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right)} \cdot n}{k}} \]
                5. Applied rewrites43.7%

                  \[\leadsto \color{blue}{\sqrt{2} \cdot \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}}} \]
                6. Step-by-step derivation
                  1. Applied rewrites43.7%

                    \[\leadsto \color{blue}{\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}} \]
                  2. Step-by-step derivation
                    1. Applied rewrites58.9%

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

                  Alternative 4: 73.4% accurate, 0.8× speedup?

                  \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 0:\\ \;\;\;\;\frac{0}{k}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{2 \cdot \frac{\mathsf{PI}\left(\right)}{k}} \cdot \sqrt{n}\\ \end{array} \end{array} \]
                  (FPCore (k n)
                   :precision binary64
                   (if (<= (* (/ 1.0 (sqrt k)) (pow (* (* 2.0 (PI)) n) (/ (- 1.0 k) 2.0))) 0.0)
                     (/ 0.0 k)
                     (* (sqrt (* 2.0 (/ (PI) k))) (sqrt n))))
                  \begin{array}{l}
                  
                  \\
                  \begin{array}{l}
                  \mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 0:\\
                  \;\;\;\;\frac{0}{k}\\
                  
                  \mathbf{else}:\\
                  \;\;\;\;\sqrt{2 \cdot \frac{\mathsf{PI}\left(\right)}{k}} \cdot \sqrt{n}\\
                  
                  
                  \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)))) < 0.0

                    1. Initial program 100.0%

                      \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
                    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. *-commutativeN/A

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

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

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

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

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

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

                        \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right) \cdot n}}{k}} \]
                      8. lower-PI.f643.2

                        \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right)} \cdot n}{k}} \]
                    5. Applied rewrites3.2%

                      \[\leadsto \color{blue}{\sqrt{2} \cdot \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}}} \]
                    6. Step-by-step derivation
                      1. Applied rewrites3.2%

                        \[\leadsto \color{blue}{\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}} \]
                      2. Step-by-step derivation
                        1. Applied rewrites3.2%

                          \[\leadsto \sqrt{\left(n \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{2}{k}} \]
                        2. Applied rewrites100.0%

                          \[\leadsto \color{blue}{\frac{0}{k}} \]

                        if 0.0 < (*.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 99.4%

                          \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
                        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. *-commutativeN/A

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

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

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

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

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

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

                            \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right) \cdot n}}{k}} \]
                          8. lower-PI.f6443.7

                            \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right)} \cdot n}{k}} \]
                        5. Applied rewrites43.7%

                          \[\leadsto \color{blue}{\sqrt{2} \cdot \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}}} \]
                        6. Step-by-step derivation
                          1. Applied rewrites43.7%

                            \[\leadsto \color{blue}{\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}} \]
                          2. Step-by-step derivation
                            1. Applied rewrites58.5%

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

                          Alternative 5: 62.8% accurate, 0.8× speedup?

                          \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 0:\\ \;\;\;\;\frac{0}{k}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{\left(\frac{n}{k} \cdot \mathsf{PI}\left(\right)\right) \cdot 2}\\ \end{array} \end{array} \]
                          (FPCore (k n)
                           :precision binary64
                           (if (<= (* (/ 1.0 (sqrt k)) (pow (* (* 2.0 (PI)) n) (/ (- 1.0 k) 2.0))) 0.0)
                             (/ 0.0 k)
                             (sqrt (* (* (/ n k) (PI)) 2.0))))
                          \begin{array}{l}
                          
                          \\
                          \begin{array}{l}
                          \mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 0:\\
                          \;\;\;\;\frac{0}{k}\\
                          
                          \mathbf{else}:\\
                          \;\;\;\;\sqrt{\left(\frac{n}{k} \cdot \mathsf{PI}\left(\right)\right) \cdot 2}\\
                          
                          
                          \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)))) < 0.0

                            1. Initial program 100.0%

                              \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
                            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. *-commutativeN/A

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

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

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

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

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

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

                                \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right) \cdot n}}{k}} \]
                              8. lower-PI.f643.2

                                \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right)} \cdot n}{k}} \]
                            5. Applied rewrites3.2%

                              \[\leadsto \color{blue}{\sqrt{2} \cdot \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}}} \]
                            6. Step-by-step derivation
                              1. Applied rewrites3.2%

                                \[\leadsto \color{blue}{\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}} \]
                              2. Step-by-step derivation
                                1. Applied rewrites3.2%

                                  \[\leadsto \sqrt{\left(n \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{2}{k}} \]
                                2. Applied rewrites100.0%

                                  \[\leadsto \color{blue}{\frac{0}{k}} \]

                                if 0.0 < (*.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 99.4%

                                  \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
                                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. *-commutativeN/A

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

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

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

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

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

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

                                    \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right) \cdot n}}{k}} \]
                                  8. lower-PI.f6443.7

                                    \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right)} \cdot n}{k}} \]
                                5. Applied rewrites43.7%

                                  \[\leadsto \color{blue}{\sqrt{2} \cdot \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}}} \]
                                6. Step-by-step derivation
                                  1. Applied rewrites43.7%

                                    \[\leadsto \color{blue}{\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}} \]
                                  2. Step-by-step derivation
                                    1. Applied rewrites43.8%

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

                                  Alternative 6: 62.8% accurate, 0.8× speedup?

                                  \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 0:\\ \;\;\;\;\frac{0}{k}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{\left(n \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{2}{k}}\\ \end{array} \end{array} \]
                                  (FPCore (k n)
                                   :precision binary64
                                   (if (<= (* (/ 1.0 (sqrt k)) (pow (* (* 2.0 (PI)) n) (/ (- 1.0 k) 2.0))) 0.0)
                                     (/ 0.0 k)
                                     (sqrt (* (* n (PI)) (/ 2.0 k)))))
                                  \begin{array}{l}
                                  
                                  \\
                                  \begin{array}{l}
                                  \mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 0:\\
                                  \;\;\;\;\frac{0}{k}\\
                                  
                                  \mathbf{else}:\\
                                  \;\;\;\;\sqrt{\left(n \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{2}{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)))) < 0.0

                                    1. Initial program 100.0%

                                      \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
                                    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. *-commutativeN/A

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

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

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

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

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

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

                                        \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right) \cdot n}}{k}} \]
                                      8. lower-PI.f643.2

                                        \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right)} \cdot n}{k}} \]
                                    5. Applied rewrites3.2%

                                      \[\leadsto \color{blue}{\sqrt{2} \cdot \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}}} \]
                                    6. Step-by-step derivation
                                      1. Applied rewrites3.2%

                                        \[\leadsto \color{blue}{\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}} \]
                                      2. Step-by-step derivation
                                        1. Applied rewrites3.2%

                                          \[\leadsto \sqrt{\left(n \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{2}{k}} \]
                                        2. Applied rewrites100.0%

                                          \[\leadsto \color{blue}{\frac{0}{k}} \]

                                        if 0.0 < (*.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 99.4%

                                          \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
                                        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. *-commutativeN/A

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

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

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

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

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

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

                                            \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right) \cdot n}}{k}} \]
                                          8. lower-PI.f6443.7

                                            \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right)} \cdot n}{k}} \]
                                        5. Applied rewrites43.7%

                                          \[\leadsto \color{blue}{\sqrt{2} \cdot \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}}} \]
                                        6. Step-by-step derivation
                                          1. Applied rewrites43.7%

                                            \[\leadsto \color{blue}{\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}} \]
                                          2. Step-by-step derivation
                                            1. Applied rewrites43.7%

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

                                          Alternative 7: 29.3% accurate, 0.8× speedup?

                                          \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 0:\\ \;\;\;\;\frac{0}{k}\\ \mathbf{else}:\\ \;\;\;\;2 \cdot \frac{\left(\mathsf{PI}\left(\right) \cdot n\right) \cdot k}{k}\\ \end{array} \end{array} \]
                                          (FPCore (k n)
                                           :precision binary64
                                           (if (<= (* (/ 1.0 (sqrt k)) (pow (* (* 2.0 (PI)) n) (/ (- 1.0 k) 2.0))) 0.0)
                                             (/ 0.0 k)
                                             (* 2.0 (/ (* (* (PI) n) k) k))))
                                          \begin{array}{l}
                                          
                                          \\
                                          \begin{array}{l}
                                          \mathbf{if}\;\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \leq 0:\\
                                          \;\;\;\;\frac{0}{k}\\
                                          
                                          \mathbf{else}:\\
                                          \;\;\;\;2 \cdot \frac{\left(\mathsf{PI}\left(\right) \cdot n\right) \cdot k}{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)))) < 0.0

                                            1. Initial program 100.0%

                                              \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
                                            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. *-commutativeN/A

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

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

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

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

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

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

                                                \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right) \cdot n}}{k}} \]
                                              8. lower-PI.f643.2

                                                \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right)} \cdot n}{k}} \]
                                            5. Applied rewrites3.2%

                                              \[\leadsto \color{blue}{\sqrt{2} \cdot \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}}} \]
                                            6. Step-by-step derivation
                                              1. Applied rewrites3.2%

                                                \[\leadsto \color{blue}{\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}} \]
                                              2. Step-by-step derivation
                                                1. Applied rewrites3.2%

                                                  \[\leadsto \sqrt{\left(n \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{2}{k}} \]
                                                2. Applied rewrites100.0%

                                                  \[\leadsto \color{blue}{\frac{0}{k}} \]

                                                if 0.0 < (*.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 99.4%

                                                  \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
                                                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. *-commutativeN/A

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

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

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

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

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

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

                                                    \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right) \cdot n}}{k}} \]
                                                  8. lower-PI.f6443.7

                                                    \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right)} \cdot n}{k}} \]
                                                5. Applied rewrites43.7%

                                                  \[\leadsto \color{blue}{\sqrt{2} \cdot \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}}} \]
                                                6. Step-by-step derivation
                                                  1. Applied rewrites43.7%

                                                    \[\leadsto \color{blue}{\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}} \]
                                                  2. Step-by-step derivation
                                                    1. Applied rewrites43.7%

                                                      \[\leadsto \sqrt{\left(n \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{2}{k}} \]
                                                    2. Applied rewrites4.6%

                                                      \[\leadsto 2 \cdot \color{blue}{\frac{\left(\mathsf{PI}\left(\right) \cdot n\right) \cdot k}{k}} \]
                                                  3. Recombined 2 regimes into one program.
                                                  4. Add Preprocessing

                                                  Alternative 8: 99.5% accurate, 1.1× speedup?

                                                  \[\begin{array}{l} \\ \frac{{\left(\mathsf{PI}\left(\right) \cdot \left(n \cdot 2\right)\right)}^{\left(\mathsf{fma}\left(-0.5, k, 0.5\right)\right)}}{\sqrt{k}} \end{array} \]
                                                  (FPCore (k n)
                                                   :precision binary64
                                                   (/ (pow (* (PI) (* n 2.0)) (fma -0.5 k 0.5)) (sqrt k)))
                                                  \begin{array}{l}
                                                  
                                                  \\
                                                  \frac{{\left(\mathsf{PI}\left(\right) \cdot \left(n \cdot 2\right)\right)}^{\left(\mathsf{fma}\left(-0.5, k, 0.5\right)\right)}}{\sqrt{k}}
                                                  \end{array}
                                                  
                                                  Derivation
                                                  1. Initial program 99.6%

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

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

                                                      \[\leadsto \frac{1}{\sqrt{k}} \cdot \color{blue}{\left(\cosh \left(\frac{1}{2} \cdot \left(\log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \left(1 - k\right)\right)\right) + \sinh \left(\frac{1}{2} \cdot \left(\log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \left(1 - k\right)\right)\right)\right)} \]
                                                    2. +-commutativeN/A

                                                      \[\leadsto \frac{1}{\sqrt{k}} \cdot \color{blue}{\left(\sinh \left(\frac{1}{2} \cdot \left(\log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \left(1 - k\right)\right)\right) + \cosh \left(\frac{1}{2} \cdot \left(\log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \left(1 - k\right)\right)\right)\right)} \]
                                                    3. distribute-rgt-out--N/A

                                                      \[\leadsto \frac{1}{\sqrt{k}} \cdot \left(\sinh \left(\frac{1}{2} \cdot \color{blue}{\left(1 \cdot \log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) - k \cdot \log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right)\right)}\right) + \cosh \left(\frac{1}{2} \cdot \left(\log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \left(1 - k\right)\right)\right)\right) \]
                                                    4. fp-cancel-sub-signN/A

                                                      \[\leadsto \frac{1}{\sqrt{k}} \cdot \left(\sinh \left(\frac{1}{2} \cdot \color{blue}{\left(1 \cdot \log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) + \left(\mathsf{neg}\left(k\right)\right) \cdot \log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right)\right)}\right) + \cosh \left(\frac{1}{2} \cdot \left(\log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \left(1 - k\right)\right)\right)\right) \]
                                                    5. mul-1-negN/A

                                                      \[\leadsto \frac{1}{\sqrt{k}} \cdot \left(\sinh \left(\frac{1}{2} \cdot \left(1 \cdot \log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) + \color{blue}{\left(-1 \cdot k\right)} \cdot \log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right)\right)\right) + \cosh \left(\frac{1}{2} \cdot \left(\log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \left(1 - k\right)\right)\right)\right) \]
                                                    6. distribute-rgt-inN/A

                                                      \[\leadsto \frac{1}{\sqrt{k}} \cdot \left(\sinh \left(\frac{1}{2} \cdot \color{blue}{\left(\log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \left(1 + -1 \cdot k\right)\right)}\right) + \cosh \left(\frac{1}{2} \cdot \left(\log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \left(1 - k\right)\right)\right)\right) \]
                                                    7. distribute-rgt-out--N/A

                                                      \[\leadsto \frac{1}{\sqrt{k}} \cdot \left(\sinh \left(\frac{1}{2} \cdot \left(\log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \left(1 + -1 \cdot k\right)\right)\right) + \cosh \left(\frac{1}{2} \cdot \color{blue}{\left(1 \cdot \log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) - k \cdot \log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right)\right)}\right)\right) \]
                                                    8. fp-cancel-sub-signN/A

                                                      \[\leadsto \frac{1}{\sqrt{k}} \cdot \left(\sinh \left(\frac{1}{2} \cdot \left(\log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \left(1 + -1 \cdot k\right)\right)\right) + \cosh \left(\frac{1}{2} \cdot \color{blue}{\left(1 \cdot \log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right) + \left(\mathsf{neg}\left(k\right)\right) \cdot \log \left(2 \cdot \left(n \cdot \mathsf{PI}\left(\right)\right)\right)\right)}\right)\right) \]
                                                  5. Applied rewrites99.6%

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

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

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

                                                      \[\leadsto \color{blue}{\frac{1 \cdot {\left(\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)\right)}^{\left(\mathsf{fma}\left(\frac{-1}{2}, k, \frac{1}{2}\right)\right)}}{\sqrt{k}}} \]
                                                    4. *-lft-identityN/A

                                                      \[\leadsto \frac{\color{blue}{{\left(\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)\right)}^{\left(\mathsf{fma}\left(\frac{-1}{2}, k, \frac{1}{2}\right)\right)}}}{\sqrt{k}} \]
                                                    5. lower-/.f6499.6

                                                      \[\leadsto \color{blue}{\frac{{\left(\left(2 \cdot n\right) \cdot \mathsf{PI}\left(\right)\right)}^{\left(\mathsf{fma}\left(-0.5, k, 0.5\right)\right)}}{\sqrt{k}}} \]
                                                  7. Applied rewrites99.6%

                                                    \[\leadsto \color{blue}{\frac{{\left(\mathsf{PI}\left(\right) \cdot \left(n \cdot 2\right)\right)}^{\left(\mathsf{fma}\left(-0.5, k, 0.5\right)\right)}}{\sqrt{k}}} \]
                                                  8. Add Preprocessing

                                                  Alternative 9: 27.4% accurate, 12.7× speedup?

                                                  \[\begin{array}{l} \\ \frac{0}{k} \end{array} \]
                                                  (FPCore (k n) :precision binary64 (/ 0.0 k))
                                                  double code(double k, double n) {
                                                  	return 0.0 / k;
                                                  }
                                                  
                                                  module fmin_fmax_functions
                                                      implicit none
                                                      private
                                                      public fmax
                                                      public fmin
                                                  
                                                      interface fmax
                                                          module procedure fmax88
                                                          module procedure fmax44
                                                          module procedure fmax84
                                                          module procedure fmax48
                                                      end interface
                                                      interface fmin
                                                          module procedure fmin88
                                                          module procedure fmin44
                                                          module procedure fmin84
                                                          module procedure fmin48
                                                      end interface
                                                  contains
                                                      real(8) function fmax88(x, y) result (res)
                                                          real(8), intent (in) :: x
                                                          real(8), intent (in) :: y
                                                          res = merge(y, merge(x, max(x, y), y /= y), x /= x)
                                                      end function
                                                      real(4) function fmax44(x, y) result (res)
                                                          real(4), intent (in) :: x
                                                          real(4), intent (in) :: y
                                                          res = merge(y, merge(x, max(x, y), y /= y), x /= x)
                                                      end function
                                                      real(8) function fmax84(x, y) result(res)
                                                          real(8), intent (in) :: x
                                                          real(4), intent (in) :: y
                                                          res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
                                                      end function
                                                      real(8) function fmax48(x, y) result(res)
                                                          real(4), intent (in) :: x
                                                          real(8), intent (in) :: y
                                                          res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
                                                      end function
                                                      real(8) function fmin88(x, y) result (res)
                                                          real(8), intent (in) :: x
                                                          real(8), intent (in) :: y
                                                          res = merge(y, merge(x, min(x, y), y /= y), x /= x)
                                                      end function
                                                      real(4) function fmin44(x, y) result (res)
                                                          real(4), intent (in) :: x
                                                          real(4), intent (in) :: y
                                                          res = merge(y, merge(x, min(x, y), y /= y), x /= x)
                                                      end function
                                                      real(8) function fmin84(x, y) result(res)
                                                          real(8), intent (in) :: x
                                                          real(4), intent (in) :: y
                                                          res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
                                                      end function
                                                      real(8) function fmin48(x, y) result(res)
                                                          real(4), intent (in) :: x
                                                          real(8), intent (in) :: y
                                                          res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
                                                      end function
                                                  end module
                                                  
                                                  real(8) function code(k, n)
                                                  use fmin_fmax_functions
                                                      real(8), intent (in) :: k
                                                      real(8), intent (in) :: n
                                                      code = 0.0d0 / k
                                                  end function
                                                  
                                                  public static double code(double k, double n) {
                                                  	return 0.0 / k;
                                                  }
                                                  
                                                  def code(k, n):
                                                  	return 0.0 / k
                                                  
                                                  function code(k, n)
                                                  	return Float64(0.0 / k)
                                                  end
                                                  
                                                  function tmp = code(k, n)
                                                  	tmp = 0.0 / k;
                                                  end
                                                  
                                                  code[k_, n_] := N[(0.0 / k), $MachinePrecision]
                                                  
                                                  \begin{array}{l}
                                                  
                                                  \\
                                                  \frac{0}{k}
                                                  \end{array}
                                                  
                                                  Derivation
                                                  1. Initial program 99.6%

                                                    \[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)} \]
                                                  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. *-commutativeN/A

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

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

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

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

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

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

                                                      \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right) \cdot n}}{k}} \]
                                                    8. lower-PI.f6431.5

                                                      \[\leadsto \sqrt{2} \cdot \sqrt{\frac{\color{blue}{\mathsf{PI}\left(\right)} \cdot n}{k}} \]
                                                  5. Applied rewrites31.5%

                                                    \[\leadsto \color{blue}{\sqrt{2} \cdot \sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k}}} \]
                                                  6. Step-by-step derivation
                                                    1. Applied rewrites31.6%

                                                      \[\leadsto \color{blue}{\sqrt{\frac{\mathsf{PI}\left(\right) \cdot n}{k} \cdot 2}} \]
                                                    2. Step-by-step derivation
                                                      1. Applied rewrites31.5%

                                                        \[\leadsto \sqrt{\left(n \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{2}{k}} \]
                                                      2. Applied rewrites31.6%

                                                        \[\leadsto \color{blue}{\frac{0}{k}} \]
                                                      3. Add Preprocessing

                                                      Reproduce

                                                      ?
                                                      herbie shell --seed 2025006 
                                                      (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))))