math.sqrt on complex, imaginary part, im greater than 0 branch

Percentage Accurate: 41.8% → 90.5%
Time: 6.8s
Alternatives: 7
Speedup: 2.0×

Specification

?
\[im > 0\]
\[\begin{array}{l} \\ 0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \end{array} \]
(FPCore (re im)
 :precision binary64
 (* 0.5 (sqrt (* 2.0 (- (sqrt (+ (* re re) (* im im))) re)))))
double code(double re, double im) {
	return 0.5 * sqrt((2.0 * (sqrt(((re * re) + (im * im))) - re)));
}
real(8) function code(re, im)
    real(8), intent (in) :: re
    real(8), intent (in) :: im
    code = 0.5d0 * sqrt((2.0d0 * (sqrt(((re * re) + (im * im))) - re)))
end function
public static double code(double re, double im) {
	return 0.5 * Math.sqrt((2.0 * (Math.sqrt(((re * re) + (im * im))) - re)));
}
def code(re, im):
	return 0.5 * math.sqrt((2.0 * (math.sqrt(((re * re) + (im * im))) - re)))
function code(re, im)
	return Float64(0.5 * sqrt(Float64(2.0 * Float64(sqrt(Float64(Float64(re * re) + Float64(im * im))) - re))))
end
function tmp = code(re, im)
	tmp = 0.5 * sqrt((2.0 * (sqrt(((re * re) + (im * im))) - re)));
end
code[re_, im_] := N[(0.5 * N[Sqrt[N[(2.0 * N[(N[Sqrt[N[(N[(re * re), $MachinePrecision] + N[(im * im), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] - re), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\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 7 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: 41.8% accurate, 1.0× speedup?

\[\begin{array}{l} \\ 0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \end{array} \]
(FPCore (re im)
 :precision binary64
 (* 0.5 (sqrt (* 2.0 (- (sqrt (+ (* re re) (* im im))) re)))))
double code(double re, double im) {
	return 0.5 * sqrt((2.0 * (sqrt(((re * re) + (im * im))) - re)));
}
real(8) function code(re, im)
    real(8), intent (in) :: re
    real(8), intent (in) :: im
    code = 0.5d0 * sqrt((2.0d0 * (sqrt(((re * re) + (im * im))) - re)))
end function
public static double code(double re, double im) {
	return 0.5 * Math.sqrt((2.0 * (Math.sqrt(((re * re) + (im * im))) - re)));
}
def code(re, im):
	return 0.5 * math.sqrt((2.0 * (math.sqrt(((re * re) + (im * im))) - re)))
function code(re, im)
	return Float64(0.5 * sqrt(Float64(2.0 * Float64(sqrt(Float64(Float64(re * re) + Float64(im * im))) - re))))
end
function tmp = code(re, im)
	tmp = 0.5 * sqrt((2.0 * (sqrt(((re * re) + (im * im))) - re)));
end
code[re_, im_] := N[(0.5 * N[Sqrt[N[(2.0 * N[(N[Sqrt[N[(N[(re * re), $MachinePrecision] + N[(im * im), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] - re), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)}
\end{array}

Alternative 1: 90.5% accurate, 0.5× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \leq 0:\\ \;\;\;\;0.5 \cdot \left(im \cdot {re}^{-0.5}\right)\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \sqrt{2 \cdot \left(\mathsf{hypot}\left(re, im\right) - re\right)}\\ \end{array} \end{array} \]
(FPCore (re im)
 :precision binary64
 (if (<= (sqrt (* 2.0 (- (sqrt (+ (* re re) (* im im))) re))) 0.0)
   (* 0.5 (* im (pow re -0.5)))
   (* 0.5 (sqrt (* 2.0 (- (hypot re im) re))))))
double code(double re, double im) {
	double tmp;
	if (sqrt((2.0 * (sqrt(((re * re) + (im * im))) - re))) <= 0.0) {
		tmp = 0.5 * (im * pow(re, -0.5));
	} else {
		tmp = 0.5 * sqrt((2.0 * (hypot(re, im) - re)));
	}
	return tmp;
}
public static double code(double re, double im) {
	double tmp;
	if (Math.sqrt((2.0 * (Math.sqrt(((re * re) + (im * im))) - re))) <= 0.0) {
		tmp = 0.5 * (im * Math.pow(re, -0.5));
	} else {
		tmp = 0.5 * Math.sqrt((2.0 * (Math.hypot(re, im) - re)));
	}
	return tmp;
}
def code(re, im):
	tmp = 0
	if math.sqrt((2.0 * (math.sqrt(((re * re) + (im * im))) - re))) <= 0.0:
		tmp = 0.5 * (im * math.pow(re, -0.5))
	else:
		tmp = 0.5 * math.sqrt((2.0 * (math.hypot(re, im) - re)))
	return tmp
function code(re, im)
	tmp = 0.0
	if (sqrt(Float64(2.0 * Float64(sqrt(Float64(Float64(re * re) + Float64(im * im))) - re))) <= 0.0)
		tmp = Float64(0.5 * Float64(im * (re ^ -0.5)));
	else
		tmp = Float64(0.5 * sqrt(Float64(2.0 * Float64(hypot(re, im) - re))));
	end
	return tmp
end
function tmp_2 = code(re, im)
	tmp = 0.0;
	if (sqrt((2.0 * (sqrt(((re * re) + (im * im))) - re))) <= 0.0)
		tmp = 0.5 * (im * (re ^ -0.5));
	else
		tmp = 0.5 * sqrt((2.0 * (hypot(re, im) - re)));
	end
	tmp_2 = tmp;
end
code[re_, im_] := If[LessEqual[N[Sqrt[N[(2.0 * N[(N[Sqrt[N[(N[(re * re), $MachinePrecision] + N[(im * im), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] - re), $MachinePrecision]), $MachinePrecision]], $MachinePrecision], 0.0], N[(0.5 * N[(im * N[Power[re, -0.5], $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(0.5 * N[Sqrt[N[(2.0 * N[(N[Sqrt[re ^ 2 + im ^ 2], $MachinePrecision] - re), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \leq 0:\\
\;\;\;\;0.5 \cdot \left(im \cdot {re}^{-0.5}\right)\\

\mathbf{else}:\\
\;\;\;\;0.5 \cdot \sqrt{2 \cdot \left(\mathsf{hypot}\left(re, im\right) - re\right)}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (sqrt.f64 (*.f64 2 (-.f64 (sqrt.f64 (+.f64 (*.f64 re re) (*.f64 im im))) re))) < 0.0

    1. Initial program 12.8%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around inf 67.0%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\frac{{im}^{2}}{re}}} \]
    3. Step-by-step derivation
      1. div-inv66.9%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{{im}^{2} \cdot \frac{1}{re}}} \]
      2. sqrt-prod69.3%

        \[\leadsto 0.5 \cdot \color{blue}{\left(\sqrt{{im}^{2}} \cdot \sqrt{\frac{1}{re}}\right)} \]
      3. unpow269.3%

        \[\leadsto 0.5 \cdot \left(\sqrt{\color{blue}{im \cdot im}} \cdot \sqrt{\frac{1}{re}}\right) \]
      4. sqrt-prod99.2%

        \[\leadsto 0.5 \cdot \left(\color{blue}{\left(\sqrt{im} \cdot \sqrt{im}\right)} \cdot \sqrt{\frac{1}{re}}\right) \]
      5. add-sqr-sqrt99.6%

        \[\leadsto 0.5 \cdot \left(\color{blue}{im} \cdot \sqrt{\frac{1}{re}}\right) \]
      6. *-commutative99.6%

        \[\leadsto 0.5 \cdot \color{blue}{\left(\sqrt{\frac{1}{re}} \cdot im\right)} \]
      7. inv-pow99.6%

        \[\leadsto 0.5 \cdot \left(\sqrt{\color{blue}{{re}^{-1}}} \cdot im\right) \]
      8. sqrt-pow199.6%

        \[\leadsto 0.5 \cdot \left(\color{blue}{{re}^{\left(\frac{-1}{2}\right)}} \cdot im\right) \]
      9. metadata-eval99.6%

        \[\leadsto 0.5 \cdot \left({re}^{\color{blue}{-0.5}} \cdot im\right) \]
    4. Applied egg-rr99.6%

      \[\leadsto 0.5 \cdot \color{blue}{\left({re}^{-0.5} \cdot im\right)} \]

    if 0.0 < (sqrt.f64 (*.f64 2 (-.f64 (sqrt.f64 (+.f64 (*.f64 re re) (*.f64 im im))) re)))

    1. Initial program 42.5%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Step-by-step derivation
      1. sub-neg42.5%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(\sqrt{re \cdot re + im \cdot im} + \left(-re\right)\right)}} \]
      2. sqr-neg42.5%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + \color{blue}{\left(-im\right) \cdot \left(-im\right)}} + \left(-re\right)\right)} \]
      3. sub-neg42.5%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(\sqrt{re \cdot re + \left(-im\right) \cdot \left(-im\right)} - re\right)}} \]
      4. sqr-neg42.5%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + \color{blue}{im \cdot im}} - re\right)} \]
      5. hypot-def89.4%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\color{blue}{\mathsf{hypot}\left(re, im\right)} - re\right)} \]
    3. Simplified89.4%

      \[\leadsto \color{blue}{0.5 \cdot \sqrt{2 \cdot \left(\mathsf{hypot}\left(re, im\right) - re\right)}} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification91.0%

    \[\leadsto \begin{array}{l} \mathbf{if}\;\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \leq 0:\\ \;\;\;\;0.5 \cdot \left(im \cdot {re}^{-0.5}\right)\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \sqrt{2 \cdot \left(\mathsf{hypot}\left(re, im\right) - re\right)}\\ \end{array} \]

Alternative 2: 74.9% accurate, 1.8× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := 0.5 \cdot \sqrt{re \cdot -4}\\ t_1 := 0.5 \cdot \sqrt{2 \cdot \left(im - re\right)}\\ \mathbf{if}\;re \leq -7.2 \cdot 10^{+59}:\\ \;\;\;\;t_0\\ \mathbf{elif}\;re \leq -4.1 \cdot 10^{-11}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;re \leq -6 \cdot 10^{-64}:\\ \;\;\;\;t_0\\ \mathbf{elif}\;re \leq 9.2 \cdot 10^{-46}:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \left(im \cdot {re}^{-0.5}\right)\\ \end{array} \end{array} \]
(FPCore (re im)
 :precision binary64
 (let* ((t_0 (* 0.5 (sqrt (* re -4.0))))
        (t_1 (* 0.5 (sqrt (* 2.0 (- im re))))))
   (if (<= re -7.2e+59)
     t_0
     (if (<= re -4.1e-11)
       t_1
       (if (<= re -6e-64)
         t_0
         (if (<= re 9.2e-46) t_1 (* 0.5 (* im (pow re -0.5)))))))))
double code(double re, double im) {
	double t_0 = 0.5 * sqrt((re * -4.0));
	double t_1 = 0.5 * sqrt((2.0 * (im - re)));
	double tmp;
	if (re <= -7.2e+59) {
		tmp = t_0;
	} else if (re <= -4.1e-11) {
		tmp = t_1;
	} else if (re <= -6e-64) {
		tmp = t_0;
	} else if (re <= 9.2e-46) {
		tmp = t_1;
	} else {
		tmp = 0.5 * (im * pow(re, -0.5));
	}
	return tmp;
}
real(8) function code(re, im)
    real(8), intent (in) :: re
    real(8), intent (in) :: im
    real(8) :: t_0
    real(8) :: t_1
    real(8) :: tmp
    t_0 = 0.5d0 * sqrt((re * (-4.0d0)))
    t_1 = 0.5d0 * sqrt((2.0d0 * (im - re)))
    if (re <= (-7.2d+59)) then
        tmp = t_0
    else if (re <= (-4.1d-11)) then
        tmp = t_1
    else if (re <= (-6d-64)) then
        tmp = t_0
    else if (re <= 9.2d-46) then
        tmp = t_1
    else
        tmp = 0.5d0 * (im * (re ** (-0.5d0)))
    end if
    code = tmp
end function
public static double code(double re, double im) {
	double t_0 = 0.5 * Math.sqrt((re * -4.0));
	double t_1 = 0.5 * Math.sqrt((2.0 * (im - re)));
	double tmp;
	if (re <= -7.2e+59) {
		tmp = t_0;
	} else if (re <= -4.1e-11) {
		tmp = t_1;
	} else if (re <= -6e-64) {
		tmp = t_0;
	} else if (re <= 9.2e-46) {
		tmp = t_1;
	} else {
		tmp = 0.5 * (im * Math.pow(re, -0.5));
	}
	return tmp;
}
def code(re, im):
	t_0 = 0.5 * math.sqrt((re * -4.0))
	t_1 = 0.5 * math.sqrt((2.0 * (im - re)))
	tmp = 0
	if re <= -7.2e+59:
		tmp = t_0
	elif re <= -4.1e-11:
		tmp = t_1
	elif re <= -6e-64:
		tmp = t_0
	elif re <= 9.2e-46:
		tmp = t_1
	else:
		tmp = 0.5 * (im * math.pow(re, -0.5))
	return tmp
function code(re, im)
	t_0 = Float64(0.5 * sqrt(Float64(re * -4.0)))
	t_1 = Float64(0.5 * sqrt(Float64(2.0 * Float64(im - re))))
	tmp = 0.0
	if (re <= -7.2e+59)
		tmp = t_0;
	elseif (re <= -4.1e-11)
		tmp = t_1;
	elseif (re <= -6e-64)
		tmp = t_0;
	elseif (re <= 9.2e-46)
		tmp = t_1;
	else
		tmp = Float64(0.5 * Float64(im * (re ^ -0.5)));
	end
	return tmp
end
function tmp_2 = code(re, im)
	t_0 = 0.5 * sqrt((re * -4.0));
	t_1 = 0.5 * sqrt((2.0 * (im - re)));
	tmp = 0.0;
	if (re <= -7.2e+59)
		tmp = t_0;
	elseif (re <= -4.1e-11)
		tmp = t_1;
	elseif (re <= -6e-64)
		tmp = t_0;
	elseif (re <= 9.2e-46)
		tmp = t_1;
	else
		tmp = 0.5 * (im * (re ^ -0.5));
	end
	tmp_2 = tmp;
end
code[re_, im_] := Block[{t$95$0 = N[(0.5 * N[Sqrt[N[(re * -4.0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, Block[{t$95$1 = N[(0.5 * N[Sqrt[N[(2.0 * N[(im - re), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, If[LessEqual[re, -7.2e+59], t$95$0, If[LessEqual[re, -4.1e-11], t$95$1, If[LessEqual[re, -6e-64], t$95$0, If[LessEqual[re, 9.2e-46], t$95$1, N[(0.5 * N[(im * N[Power[re, -0.5], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := 0.5 \cdot \sqrt{re \cdot -4}\\
t_1 := 0.5 \cdot \sqrt{2 \cdot \left(im - re\right)}\\
\mathbf{if}\;re \leq -7.2 \cdot 10^{+59}:\\
\;\;\;\;t_0\\

\mathbf{elif}\;re \leq -4.1 \cdot 10^{-11}:\\
\;\;\;\;t_1\\

\mathbf{elif}\;re \leq -6 \cdot 10^{-64}:\\
\;\;\;\;t_0\\

\mathbf{elif}\;re \leq 9.2 \cdot 10^{-46}:\\
\;\;\;\;t_1\\

\mathbf{else}:\\
\;\;\;\;0.5 \cdot \left(im \cdot {re}^{-0.5}\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if re < -7.1999999999999997e59 or -4.1000000000000001e-11 < re < -6.0000000000000001e-64

    1. Initial program 37.3%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around -inf 84.9%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{-4 \cdot re}} \]
    3. Step-by-step derivation
      1. *-commutative84.9%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot -4}} \]
    4. Simplified84.9%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot -4}} \]

    if -7.1999999999999997e59 < re < -4.1000000000000001e-11 or -6.0000000000000001e-64 < re < 9.1999999999999997e-46

    1. Initial program 50.8%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around 0 76.2%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\color{blue}{im} - re\right)} \]

    if 9.1999999999999997e-46 < re

    1. Initial program 14.9%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around inf 53.9%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\frac{{im}^{2}}{re}}} \]
    3. Step-by-step derivation
      1. div-inv53.9%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{{im}^{2} \cdot \frac{1}{re}}} \]
      2. sqrt-prod63.2%

        \[\leadsto 0.5 \cdot \color{blue}{\left(\sqrt{{im}^{2}} \cdot \sqrt{\frac{1}{re}}\right)} \]
      3. unpow263.2%

        \[\leadsto 0.5 \cdot \left(\sqrt{\color{blue}{im \cdot im}} \cdot \sqrt{\frac{1}{re}}\right) \]
      4. sqrt-prod77.5%

        \[\leadsto 0.5 \cdot \left(\color{blue}{\left(\sqrt{im} \cdot \sqrt{im}\right)} \cdot \sqrt{\frac{1}{re}}\right) \]
      5. add-sqr-sqrt77.8%

        \[\leadsto 0.5 \cdot \left(\color{blue}{im} \cdot \sqrt{\frac{1}{re}}\right) \]
      6. *-commutative77.8%

        \[\leadsto 0.5 \cdot \color{blue}{\left(\sqrt{\frac{1}{re}} \cdot im\right)} \]
      7. inv-pow77.8%

        \[\leadsto 0.5 \cdot \left(\sqrt{\color{blue}{{re}^{-1}}} \cdot im\right) \]
      8. sqrt-pow177.8%

        \[\leadsto 0.5 \cdot \left(\color{blue}{{re}^{\left(\frac{-1}{2}\right)}} \cdot im\right) \]
      9. metadata-eval77.8%

        \[\leadsto 0.5 \cdot \left({re}^{\color{blue}{-0.5}} \cdot im\right) \]
    4. Applied egg-rr77.8%

      \[\leadsto 0.5 \cdot \color{blue}{\left({re}^{-0.5} \cdot im\right)} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification78.6%

    \[\leadsto \begin{array}{l} \mathbf{if}\;re \leq -7.2 \cdot 10^{+59}:\\ \;\;\;\;0.5 \cdot \sqrt{re \cdot -4}\\ \mathbf{elif}\;re \leq -4.1 \cdot 10^{-11}:\\ \;\;\;\;0.5 \cdot \sqrt{2 \cdot \left(im - re\right)}\\ \mathbf{elif}\;re \leq -6 \cdot 10^{-64}:\\ \;\;\;\;0.5 \cdot \sqrt{re \cdot -4}\\ \mathbf{elif}\;re \leq 9.2 \cdot 10^{-46}:\\ \;\;\;\;0.5 \cdot \sqrt{2 \cdot \left(im - re\right)}\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \left(im \cdot {re}^{-0.5}\right)\\ \end{array} \]

Alternative 3: 74.9% accurate, 1.8× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := 0.5 \cdot \sqrt{re \cdot -4}\\ t_1 := 0.5 \cdot \sqrt{2 \cdot \left(im - re\right)}\\ \mathbf{if}\;re \leq -9.2 \cdot 10^{+59}:\\ \;\;\;\;t_0\\ \mathbf{elif}\;re \leq -1.6 \cdot 10^{-9}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;re \leq -1.6 \cdot 10^{-63}:\\ \;\;\;\;t_0\\ \mathbf{elif}\;re \leq 2.1 \cdot 10^{-45}:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \left(im \cdot \sqrt{\frac{1}{re}}\right)\\ \end{array} \end{array} \]
(FPCore (re im)
 :precision binary64
 (let* ((t_0 (* 0.5 (sqrt (* re -4.0))))
        (t_1 (* 0.5 (sqrt (* 2.0 (- im re))))))
   (if (<= re -9.2e+59)
     t_0
     (if (<= re -1.6e-9)
       t_1
       (if (<= re -1.6e-63)
         t_0
         (if (<= re 2.1e-45) t_1 (* 0.5 (* im (sqrt (/ 1.0 re))))))))))
double code(double re, double im) {
	double t_0 = 0.5 * sqrt((re * -4.0));
	double t_1 = 0.5 * sqrt((2.0 * (im - re)));
	double tmp;
	if (re <= -9.2e+59) {
		tmp = t_0;
	} else if (re <= -1.6e-9) {
		tmp = t_1;
	} else if (re <= -1.6e-63) {
		tmp = t_0;
	} else if (re <= 2.1e-45) {
		tmp = t_1;
	} else {
		tmp = 0.5 * (im * sqrt((1.0 / re)));
	}
	return tmp;
}
real(8) function code(re, im)
    real(8), intent (in) :: re
    real(8), intent (in) :: im
    real(8) :: t_0
    real(8) :: t_1
    real(8) :: tmp
    t_0 = 0.5d0 * sqrt((re * (-4.0d0)))
    t_1 = 0.5d0 * sqrt((2.0d0 * (im - re)))
    if (re <= (-9.2d+59)) then
        tmp = t_0
    else if (re <= (-1.6d-9)) then
        tmp = t_1
    else if (re <= (-1.6d-63)) then
        tmp = t_0
    else if (re <= 2.1d-45) then
        tmp = t_1
    else
        tmp = 0.5d0 * (im * sqrt((1.0d0 / re)))
    end if
    code = tmp
end function
public static double code(double re, double im) {
	double t_0 = 0.5 * Math.sqrt((re * -4.0));
	double t_1 = 0.5 * Math.sqrt((2.0 * (im - re)));
	double tmp;
	if (re <= -9.2e+59) {
		tmp = t_0;
	} else if (re <= -1.6e-9) {
		tmp = t_1;
	} else if (re <= -1.6e-63) {
		tmp = t_0;
	} else if (re <= 2.1e-45) {
		tmp = t_1;
	} else {
		tmp = 0.5 * (im * Math.sqrt((1.0 / re)));
	}
	return tmp;
}
def code(re, im):
	t_0 = 0.5 * math.sqrt((re * -4.0))
	t_1 = 0.5 * math.sqrt((2.0 * (im - re)))
	tmp = 0
	if re <= -9.2e+59:
		tmp = t_0
	elif re <= -1.6e-9:
		tmp = t_1
	elif re <= -1.6e-63:
		tmp = t_0
	elif re <= 2.1e-45:
		tmp = t_1
	else:
		tmp = 0.5 * (im * math.sqrt((1.0 / re)))
	return tmp
function code(re, im)
	t_0 = Float64(0.5 * sqrt(Float64(re * -4.0)))
	t_1 = Float64(0.5 * sqrt(Float64(2.0 * Float64(im - re))))
	tmp = 0.0
	if (re <= -9.2e+59)
		tmp = t_0;
	elseif (re <= -1.6e-9)
		tmp = t_1;
	elseif (re <= -1.6e-63)
		tmp = t_0;
	elseif (re <= 2.1e-45)
		tmp = t_1;
	else
		tmp = Float64(0.5 * Float64(im * sqrt(Float64(1.0 / re))));
	end
	return tmp
end
function tmp_2 = code(re, im)
	t_0 = 0.5 * sqrt((re * -4.0));
	t_1 = 0.5 * sqrt((2.0 * (im - re)));
	tmp = 0.0;
	if (re <= -9.2e+59)
		tmp = t_0;
	elseif (re <= -1.6e-9)
		tmp = t_1;
	elseif (re <= -1.6e-63)
		tmp = t_0;
	elseif (re <= 2.1e-45)
		tmp = t_1;
	else
		tmp = 0.5 * (im * sqrt((1.0 / re)));
	end
	tmp_2 = tmp;
end
code[re_, im_] := Block[{t$95$0 = N[(0.5 * N[Sqrt[N[(re * -4.0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, Block[{t$95$1 = N[(0.5 * N[Sqrt[N[(2.0 * N[(im - re), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, If[LessEqual[re, -9.2e+59], t$95$0, If[LessEqual[re, -1.6e-9], t$95$1, If[LessEqual[re, -1.6e-63], t$95$0, If[LessEqual[re, 2.1e-45], t$95$1, N[(0.5 * N[(im * N[Sqrt[N[(1.0 / re), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := 0.5 \cdot \sqrt{re \cdot -4}\\
t_1 := 0.5 \cdot \sqrt{2 \cdot \left(im - re\right)}\\
\mathbf{if}\;re \leq -9.2 \cdot 10^{+59}:\\
\;\;\;\;t_0\\

\mathbf{elif}\;re \leq -1.6 \cdot 10^{-9}:\\
\;\;\;\;t_1\\

\mathbf{elif}\;re \leq -1.6 \cdot 10^{-63}:\\
\;\;\;\;t_0\\

\mathbf{elif}\;re \leq 2.1 \cdot 10^{-45}:\\
\;\;\;\;t_1\\

\mathbf{else}:\\
\;\;\;\;0.5 \cdot \left(im \cdot \sqrt{\frac{1}{re}}\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if re < -9.20000000000000032e59 or -1.60000000000000006e-9 < re < -1.59999999999999994e-63

    1. Initial program 37.3%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around -inf 84.9%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{-4 \cdot re}} \]
    3. Step-by-step derivation
      1. *-commutative84.9%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot -4}} \]
    4. Simplified84.9%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot -4}} \]

    if -9.20000000000000032e59 < re < -1.60000000000000006e-9 or -1.59999999999999994e-63 < re < 2.09999999999999995e-45

    1. Initial program 50.8%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around 0 76.2%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\color{blue}{im} - re\right)} \]

    if 2.09999999999999995e-45 < re

    1. Initial program 14.9%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around inf 53.9%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\frac{{im}^{2}}{re}}} \]
    3. Taylor expanded in im around 0 77.8%

      \[\leadsto 0.5 \cdot \color{blue}{\left(im \cdot \sqrt{\frac{1}{re}}\right)} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification78.6%

    \[\leadsto \begin{array}{l} \mathbf{if}\;re \leq -9.2 \cdot 10^{+59}:\\ \;\;\;\;0.5 \cdot \sqrt{re \cdot -4}\\ \mathbf{elif}\;re \leq -1.6 \cdot 10^{-9}:\\ \;\;\;\;0.5 \cdot \sqrt{2 \cdot \left(im - re\right)}\\ \mathbf{elif}\;re \leq -1.6 \cdot 10^{-63}:\\ \;\;\;\;0.5 \cdot \sqrt{re \cdot -4}\\ \mathbf{elif}\;re \leq 2.1 \cdot 10^{-45}:\\ \;\;\;\;0.5 \cdot \sqrt{2 \cdot \left(im - re\right)}\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \left(im \cdot \sqrt{\frac{1}{re}}\right)\\ \end{array} \]

Alternative 4: 74.2% accurate, 1.9× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := 0.5 \cdot \sqrt{re \cdot -4}\\ t_1 := 0.5 \cdot \sqrt{2 \cdot im}\\ \mathbf{if}\;re \leq -5 \cdot 10^{+48}:\\ \;\;\;\;t_0\\ \mathbf{elif}\;re \leq -0.0034:\\ \;\;\;\;t_1\\ \mathbf{elif}\;re \leq -1 \cdot 10^{-64}:\\ \;\;\;\;t_0\\ \mathbf{elif}\;re \leq 1.55 \cdot 10^{-43}:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \left(im \cdot {re}^{-0.5}\right)\\ \end{array} \end{array} \]
(FPCore (re im)
 :precision binary64
 (let* ((t_0 (* 0.5 (sqrt (* re -4.0)))) (t_1 (* 0.5 (sqrt (* 2.0 im)))))
   (if (<= re -5e+48)
     t_0
     (if (<= re -0.0034)
       t_1
       (if (<= re -1e-64)
         t_0
         (if (<= re 1.55e-43) t_1 (* 0.5 (* im (pow re -0.5)))))))))
double code(double re, double im) {
	double t_0 = 0.5 * sqrt((re * -4.0));
	double t_1 = 0.5 * sqrt((2.0 * im));
	double tmp;
	if (re <= -5e+48) {
		tmp = t_0;
	} else if (re <= -0.0034) {
		tmp = t_1;
	} else if (re <= -1e-64) {
		tmp = t_0;
	} else if (re <= 1.55e-43) {
		tmp = t_1;
	} else {
		tmp = 0.5 * (im * pow(re, -0.5));
	}
	return tmp;
}
real(8) function code(re, im)
    real(8), intent (in) :: re
    real(8), intent (in) :: im
    real(8) :: t_0
    real(8) :: t_1
    real(8) :: tmp
    t_0 = 0.5d0 * sqrt((re * (-4.0d0)))
    t_1 = 0.5d0 * sqrt((2.0d0 * im))
    if (re <= (-5d+48)) then
        tmp = t_0
    else if (re <= (-0.0034d0)) then
        tmp = t_1
    else if (re <= (-1d-64)) then
        tmp = t_0
    else if (re <= 1.55d-43) then
        tmp = t_1
    else
        tmp = 0.5d0 * (im * (re ** (-0.5d0)))
    end if
    code = tmp
end function
public static double code(double re, double im) {
	double t_0 = 0.5 * Math.sqrt((re * -4.0));
	double t_1 = 0.5 * Math.sqrt((2.0 * im));
	double tmp;
	if (re <= -5e+48) {
		tmp = t_0;
	} else if (re <= -0.0034) {
		tmp = t_1;
	} else if (re <= -1e-64) {
		tmp = t_0;
	} else if (re <= 1.55e-43) {
		tmp = t_1;
	} else {
		tmp = 0.5 * (im * Math.pow(re, -0.5));
	}
	return tmp;
}
def code(re, im):
	t_0 = 0.5 * math.sqrt((re * -4.0))
	t_1 = 0.5 * math.sqrt((2.0 * im))
	tmp = 0
	if re <= -5e+48:
		tmp = t_0
	elif re <= -0.0034:
		tmp = t_1
	elif re <= -1e-64:
		tmp = t_0
	elif re <= 1.55e-43:
		tmp = t_1
	else:
		tmp = 0.5 * (im * math.pow(re, -0.5))
	return tmp
function code(re, im)
	t_0 = Float64(0.5 * sqrt(Float64(re * -4.0)))
	t_1 = Float64(0.5 * sqrt(Float64(2.0 * im)))
	tmp = 0.0
	if (re <= -5e+48)
		tmp = t_0;
	elseif (re <= -0.0034)
		tmp = t_1;
	elseif (re <= -1e-64)
		tmp = t_0;
	elseif (re <= 1.55e-43)
		tmp = t_1;
	else
		tmp = Float64(0.5 * Float64(im * (re ^ -0.5)));
	end
	return tmp
end
function tmp_2 = code(re, im)
	t_0 = 0.5 * sqrt((re * -4.0));
	t_1 = 0.5 * sqrt((2.0 * im));
	tmp = 0.0;
	if (re <= -5e+48)
		tmp = t_0;
	elseif (re <= -0.0034)
		tmp = t_1;
	elseif (re <= -1e-64)
		tmp = t_0;
	elseif (re <= 1.55e-43)
		tmp = t_1;
	else
		tmp = 0.5 * (im * (re ^ -0.5));
	end
	tmp_2 = tmp;
end
code[re_, im_] := Block[{t$95$0 = N[(0.5 * N[Sqrt[N[(re * -4.0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, Block[{t$95$1 = N[(0.5 * N[Sqrt[N[(2.0 * im), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, If[LessEqual[re, -5e+48], t$95$0, If[LessEqual[re, -0.0034], t$95$1, If[LessEqual[re, -1e-64], t$95$0, If[LessEqual[re, 1.55e-43], t$95$1, N[(0.5 * N[(im * N[Power[re, -0.5], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := 0.5 \cdot \sqrt{re \cdot -4}\\
t_1 := 0.5 \cdot \sqrt{2 \cdot im}\\
\mathbf{if}\;re \leq -5 \cdot 10^{+48}:\\
\;\;\;\;t_0\\

\mathbf{elif}\;re \leq -0.0034:\\
\;\;\;\;t_1\\

\mathbf{elif}\;re \leq -1 \cdot 10^{-64}:\\
\;\;\;\;t_0\\

\mathbf{elif}\;re \leq 1.55 \cdot 10^{-43}:\\
\;\;\;\;t_1\\

\mathbf{else}:\\
\;\;\;\;0.5 \cdot \left(im \cdot {re}^{-0.5}\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if re < -4.99999999999999973e48 or -0.00339999999999999981 < re < -9.99999999999999965e-65

    1. Initial program 41.7%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around -inf 82.0%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{-4 \cdot re}} \]
    3. Step-by-step derivation
      1. *-commutative82.0%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot -4}} \]
    4. Simplified82.0%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot -4}} \]

    if -4.99999999999999973e48 < re < -0.00339999999999999981 or -9.99999999999999965e-65 < re < 1.55e-43

    1. Initial program 49.2%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around 0 76.3%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot im}} \]
    3. Step-by-step derivation
      1. *-commutative76.3%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{im \cdot 2}} \]
    4. Simplified76.3%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{im \cdot 2}} \]

    if 1.55e-43 < re

    1. Initial program 14.9%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around inf 53.9%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\frac{{im}^{2}}{re}}} \]
    3. Step-by-step derivation
      1. div-inv53.9%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{{im}^{2} \cdot \frac{1}{re}}} \]
      2. sqrt-prod63.2%

        \[\leadsto 0.5 \cdot \color{blue}{\left(\sqrt{{im}^{2}} \cdot \sqrt{\frac{1}{re}}\right)} \]
      3. unpow263.2%

        \[\leadsto 0.5 \cdot \left(\sqrt{\color{blue}{im \cdot im}} \cdot \sqrt{\frac{1}{re}}\right) \]
      4. sqrt-prod77.5%

        \[\leadsto 0.5 \cdot \left(\color{blue}{\left(\sqrt{im} \cdot \sqrt{im}\right)} \cdot \sqrt{\frac{1}{re}}\right) \]
      5. add-sqr-sqrt77.8%

        \[\leadsto 0.5 \cdot \left(\color{blue}{im} \cdot \sqrt{\frac{1}{re}}\right) \]
      6. *-commutative77.8%

        \[\leadsto 0.5 \cdot \color{blue}{\left(\sqrt{\frac{1}{re}} \cdot im\right)} \]
      7. inv-pow77.8%

        \[\leadsto 0.5 \cdot \left(\sqrt{\color{blue}{{re}^{-1}}} \cdot im\right) \]
      8. sqrt-pow177.8%

        \[\leadsto 0.5 \cdot \left(\color{blue}{{re}^{\left(\frac{-1}{2}\right)}} \cdot im\right) \]
      9. metadata-eval77.8%

        \[\leadsto 0.5 \cdot \left({re}^{\color{blue}{-0.5}} \cdot im\right) \]
    4. Applied egg-rr77.8%

      \[\leadsto 0.5 \cdot \color{blue}{\left({re}^{-0.5} \cdot im\right)} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification78.1%

    \[\leadsto \begin{array}{l} \mathbf{if}\;re \leq -5 \cdot 10^{+48}:\\ \;\;\;\;0.5 \cdot \sqrt{re \cdot -4}\\ \mathbf{elif}\;re \leq -0.0034:\\ \;\;\;\;0.5 \cdot \sqrt{2 \cdot im}\\ \mathbf{elif}\;re \leq -1 \cdot 10^{-64}:\\ \;\;\;\;0.5 \cdot \sqrt{re \cdot -4}\\ \mathbf{elif}\;re \leq 1.55 \cdot 10^{-43}:\\ \;\;\;\;0.5 \cdot \sqrt{2 \cdot im}\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \left(im \cdot {re}^{-0.5}\right)\\ \end{array} \]

Alternative 5: 74.3% accurate, 1.9× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := 0.5 \cdot \sqrt{re \cdot -4}\\ t_1 := 0.5 \cdot \sqrt{2 \cdot im}\\ \mathbf{if}\;re \leq -4.2 \cdot 10^{+44}:\\ \;\;\;\;t_0\\ \mathbf{elif}\;re \leq -0.004:\\ \;\;\;\;t_1\\ \mathbf{elif}\;re \leq -4 \cdot 10^{-63}:\\ \;\;\;\;t_0\\ \mathbf{elif}\;re \leq 2.15 \cdot 10^{-45}:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \frac{im}{\sqrt{re}}\\ \end{array} \end{array} \]
(FPCore (re im)
 :precision binary64
 (let* ((t_0 (* 0.5 (sqrt (* re -4.0)))) (t_1 (* 0.5 (sqrt (* 2.0 im)))))
   (if (<= re -4.2e+44)
     t_0
     (if (<= re -0.004)
       t_1
       (if (<= re -4e-63)
         t_0
         (if (<= re 2.15e-45) t_1 (* 0.5 (/ im (sqrt re)))))))))
double code(double re, double im) {
	double t_0 = 0.5 * sqrt((re * -4.0));
	double t_1 = 0.5 * sqrt((2.0 * im));
	double tmp;
	if (re <= -4.2e+44) {
		tmp = t_0;
	} else if (re <= -0.004) {
		tmp = t_1;
	} else if (re <= -4e-63) {
		tmp = t_0;
	} else if (re <= 2.15e-45) {
		tmp = t_1;
	} else {
		tmp = 0.5 * (im / sqrt(re));
	}
	return tmp;
}
real(8) function code(re, im)
    real(8), intent (in) :: re
    real(8), intent (in) :: im
    real(8) :: t_0
    real(8) :: t_1
    real(8) :: tmp
    t_0 = 0.5d0 * sqrt((re * (-4.0d0)))
    t_1 = 0.5d0 * sqrt((2.0d0 * im))
    if (re <= (-4.2d+44)) then
        tmp = t_0
    else if (re <= (-0.004d0)) then
        tmp = t_1
    else if (re <= (-4d-63)) then
        tmp = t_0
    else if (re <= 2.15d-45) then
        tmp = t_1
    else
        tmp = 0.5d0 * (im / sqrt(re))
    end if
    code = tmp
end function
public static double code(double re, double im) {
	double t_0 = 0.5 * Math.sqrt((re * -4.0));
	double t_1 = 0.5 * Math.sqrt((2.0 * im));
	double tmp;
	if (re <= -4.2e+44) {
		tmp = t_0;
	} else if (re <= -0.004) {
		tmp = t_1;
	} else if (re <= -4e-63) {
		tmp = t_0;
	} else if (re <= 2.15e-45) {
		tmp = t_1;
	} else {
		tmp = 0.5 * (im / Math.sqrt(re));
	}
	return tmp;
}
def code(re, im):
	t_0 = 0.5 * math.sqrt((re * -4.0))
	t_1 = 0.5 * math.sqrt((2.0 * im))
	tmp = 0
	if re <= -4.2e+44:
		tmp = t_0
	elif re <= -0.004:
		tmp = t_1
	elif re <= -4e-63:
		tmp = t_0
	elif re <= 2.15e-45:
		tmp = t_1
	else:
		tmp = 0.5 * (im / math.sqrt(re))
	return tmp
function code(re, im)
	t_0 = Float64(0.5 * sqrt(Float64(re * -4.0)))
	t_1 = Float64(0.5 * sqrt(Float64(2.0 * im)))
	tmp = 0.0
	if (re <= -4.2e+44)
		tmp = t_0;
	elseif (re <= -0.004)
		tmp = t_1;
	elseif (re <= -4e-63)
		tmp = t_0;
	elseif (re <= 2.15e-45)
		tmp = t_1;
	else
		tmp = Float64(0.5 * Float64(im / sqrt(re)));
	end
	return tmp
end
function tmp_2 = code(re, im)
	t_0 = 0.5 * sqrt((re * -4.0));
	t_1 = 0.5 * sqrt((2.0 * im));
	tmp = 0.0;
	if (re <= -4.2e+44)
		tmp = t_0;
	elseif (re <= -0.004)
		tmp = t_1;
	elseif (re <= -4e-63)
		tmp = t_0;
	elseif (re <= 2.15e-45)
		tmp = t_1;
	else
		tmp = 0.5 * (im / sqrt(re));
	end
	tmp_2 = tmp;
end
code[re_, im_] := Block[{t$95$0 = N[(0.5 * N[Sqrt[N[(re * -4.0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, Block[{t$95$1 = N[(0.5 * N[Sqrt[N[(2.0 * im), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, If[LessEqual[re, -4.2e+44], t$95$0, If[LessEqual[re, -0.004], t$95$1, If[LessEqual[re, -4e-63], t$95$0, If[LessEqual[re, 2.15e-45], t$95$1, N[(0.5 * N[(im / N[Sqrt[re], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := 0.5 \cdot \sqrt{re \cdot -4}\\
t_1 := 0.5 \cdot \sqrt{2 \cdot im}\\
\mathbf{if}\;re \leq -4.2 \cdot 10^{+44}:\\
\;\;\;\;t_0\\

\mathbf{elif}\;re \leq -0.004:\\
\;\;\;\;t_1\\

\mathbf{elif}\;re \leq -4 \cdot 10^{-63}:\\
\;\;\;\;t_0\\

\mathbf{elif}\;re \leq 2.15 \cdot 10^{-45}:\\
\;\;\;\;t_1\\

\mathbf{else}:\\
\;\;\;\;0.5 \cdot \frac{im}{\sqrt{re}}\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if re < -4.19999999999999974e44 or -0.0040000000000000001 < re < -4.00000000000000027e-63

    1. Initial program 41.7%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around -inf 82.0%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{-4 \cdot re}} \]
    3. Step-by-step derivation
      1. *-commutative82.0%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot -4}} \]
    4. Simplified82.0%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot -4}} \]

    if -4.19999999999999974e44 < re < -0.0040000000000000001 or -4.00000000000000027e-63 < re < 2.1499999999999999e-45

    1. Initial program 49.2%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around 0 76.3%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot im}} \]
    3. Step-by-step derivation
      1. *-commutative76.3%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{im \cdot 2}} \]
    4. Simplified76.3%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{im \cdot 2}} \]

    if 2.1499999999999999e-45 < re

    1. Initial program 14.9%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around inf 53.9%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\frac{{im}^{2}}{re}}} \]
    3. Taylor expanded in im around 0 77.8%

      \[\leadsto 0.5 \cdot \color{blue}{\left(im \cdot \sqrt{\frac{1}{re}}\right)} \]
    4. Step-by-step derivation
      1. *-commutative77.8%

        \[\leadsto 0.5 \cdot \color{blue}{\left(\sqrt{\frac{1}{re}} \cdot im\right)} \]
      2. unpow-177.8%

        \[\leadsto 0.5 \cdot \left(\sqrt{\color{blue}{{re}^{-1}}} \cdot im\right) \]
      3. metadata-eval77.8%

        \[\leadsto 0.5 \cdot \left(\sqrt{{re}^{\color{blue}{\left(2 \cdot -0.5\right)}}} \cdot im\right) \]
      4. pow-sqr77.8%

        \[\leadsto 0.5 \cdot \left(\sqrt{\color{blue}{{re}^{-0.5} \cdot {re}^{-0.5}}} \cdot im\right) \]
      5. rem-sqrt-square77.8%

        \[\leadsto 0.5 \cdot \left(\color{blue}{\left|{re}^{-0.5}\right|} \cdot im\right) \]
      6. rem-square-sqrt77.5%

        \[\leadsto 0.5 \cdot \left(\left|\color{blue}{\sqrt{{re}^{-0.5}} \cdot \sqrt{{re}^{-0.5}}}\right| \cdot im\right) \]
      7. fabs-sqr77.5%

        \[\leadsto 0.5 \cdot \left(\color{blue}{\left(\sqrt{{re}^{-0.5}} \cdot \sqrt{{re}^{-0.5}}\right)} \cdot im\right) \]
      8. rem-square-sqrt77.8%

        \[\leadsto 0.5 \cdot \left(\color{blue}{{re}^{-0.5}} \cdot im\right) \]
      9. exp-to-pow73.8%

        \[\leadsto 0.5 \cdot \left(\color{blue}{e^{\log re \cdot -0.5}} \cdot im\right) \]
      10. metadata-eval73.8%

        \[\leadsto 0.5 \cdot \left(e^{\log re \cdot \color{blue}{\left(-0.5\right)}} \cdot im\right) \]
      11. distribute-rgt-neg-in73.8%

        \[\leadsto 0.5 \cdot \left(e^{\color{blue}{-\log re \cdot 0.5}} \cdot im\right) \]
      12. exp-neg73.8%

        \[\leadsto 0.5 \cdot \left(\color{blue}{\frac{1}{e^{\log re \cdot 0.5}}} \cdot im\right) \]
      13. exp-to-pow77.8%

        \[\leadsto 0.5 \cdot \left(\frac{1}{\color{blue}{{re}^{0.5}}} \cdot im\right) \]
      14. unpow1/277.8%

        \[\leadsto 0.5 \cdot \left(\frac{1}{\color{blue}{\sqrt{re}}} \cdot im\right) \]
      15. associate-*l/77.7%

        \[\leadsto 0.5 \cdot \color{blue}{\frac{1 \cdot im}{\sqrt{re}}} \]
      16. *-lft-identity77.7%

        \[\leadsto 0.5 \cdot \frac{\color{blue}{im}}{\sqrt{re}} \]
    5. Simplified77.7%

      \[\leadsto 0.5 \cdot \color{blue}{\frac{im}{\sqrt{re}}} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification78.1%

    \[\leadsto \begin{array}{l} \mathbf{if}\;re \leq -4.2 \cdot 10^{+44}:\\ \;\;\;\;0.5 \cdot \sqrt{re \cdot -4}\\ \mathbf{elif}\;re \leq -0.004:\\ \;\;\;\;0.5 \cdot \sqrt{2 \cdot im}\\ \mathbf{elif}\;re \leq -4 \cdot 10^{-63}:\\ \;\;\;\;0.5 \cdot \sqrt{re \cdot -4}\\ \mathbf{elif}\;re \leq 2.15 \cdot 10^{-45}:\\ \;\;\;\;0.5 \cdot \sqrt{2 \cdot im}\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \frac{im}{\sqrt{re}}\\ \end{array} \]

Alternative 6: 63.4% accurate, 1.9× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;re \leq -4.2 \cdot 10^{+44} \lor \neg \left(re \leq -0.0038\right) \land re \leq -2.95 \cdot 10^{-64}:\\ \;\;\;\;0.5 \cdot \sqrt{re \cdot -4}\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \sqrt{2 \cdot im}\\ \end{array} \end{array} \]
(FPCore (re im)
 :precision binary64
 (if (or (<= re -4.2e+44) (and (not (<= re -0.0038)) (<= re -2.95e-64)))
   (* 0.5 (sqrt (* re -4.0)))
   (* 0.5 (sqrt (* 2.0 im)))))
double code(double re, double im) {
	double tmp;
	if ((re <= -4.2e+44) || (!(re <= -0.0038) && (re <= -2.95e-64))) {
		tmp = 0.5 * sqrt((re * -4.0));
	} else {
		tmp = 0.5 * sqrt((2.0 * im));
	}
	return tmp;
}
real(8) function code(re, im)
    real(8), intent (in) :: re
    real(8), intent (in) :: im
    real(8) :: tmp
    if ((re <= (-4.2d+44)) .or. (.not. (re <= (-0.0038d0))) .and. (re <= (-2.95d-64))) then
        tmp = 0.5d0 * sqrt((re * (-4.0d0)))
    else
        tmp = 0.5d0 * sqrt((2.0d0 * im))
    end if
    code = tmp
end function
public static double code(double re, double im) {
	double tmp;
	if ((re <= -4.2e+44) || (!(re <= -0.0038) && (re <= -2.95e-64))) {
		tmp = 0.5 * Math.sqrt((re * -4.0));
	} else {
		tmp = 0.5 * Math.sqrt((2.0 * im));
	}
	return tmp;
}
def code(re, im):
	tmp = 0
	if (re <= -4.2e+44) or (not (re <= -0.0038) and (re <= -2.95e-64)):
		tmp = 0.5 * math.sqrt((re * -4.0))
	else:
		tmp = 0.5 * math.sqrt((2.0 * im))
	return tmp
function code(re, im)
	tmp = 0.0
	if ((re <= -4.2e+44) || (!(re <= -0.0038) && (re <= -2.95e-64)))
		tmp = Float64(0.5 * sqrt(Float64(re * -4.0)));
	else
		tmp = Float64(0.5 * sqrt(Float64(2.0 * im)));
	end
	return tmp
end
function tmp_2 = code(re, im)
	tmp = 0.0;
	if ((re <= -4.2e+44) || (~((re <= -0.0038)) && (re <= -2.95e-64)))
		tmp = 0.5 * sqrt((re * -4.0));
	else
		tmp = 0.5 * sqrt((2.0 * im));
	end
	tmp_2 = tmp;
end
code[re_, im_] := If[Or[LessEqual[re, -4.2e+44], And[N[Not[LessEqual[re, -0.0038]], $MachinePrecision], LessEqual[re, -2.95e-64]]], N[(0.5 * N[Sqrt[N[(re * -4.0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], N[(0.5 * N[Sqrt[N[(2.0 * im), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;re \leq -4.2 \cdot 10^{+44} \lor \neg \left(re \leq -0.0038\right) \land re \leq -2.95 \cdot 10^{-64}:\\
\;\;\;\;0.5 \cdot \sqrt{re \cdot -4}\\

\mathbf{else}:\\
\;\;\;\;0.5 \cdot \sqrt{2 \cdot im}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if re < -4.19999999999999974e44 or -0.00379999999999999999 < re < -2.94999999999999997e-64

    1. Initial program 41.7%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around -inf 82.0%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{-4 \cdot re}} \]
    3. Step-by-step derivation
      1. *-commutative82.0%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot -4}} \]
    4. Simplified82.0%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot -4}} \]

    if -4.19999999999999974e44 < re < -0.00379999999999999999 or -2.94999999999999997e-64 < re

    1. Initial program 36.7%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Taylor expanded in re around 0 58.7%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot im}} \]
    3. Step-by-step derivation
      1. *-commutative58.7%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{im \cdot 2}} \]
    4. Simplified58.7%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{im \cdot 2}} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification64.5%

    \[\leadsto \begin{array}{l} \mathbf{if}\;re \leq -4.2 \cdot 10^{+44} \lor \neg \left(re \leq -0.0038\right) \land re \leq -2.95 \cdot 10^{-64}:\\ \;\;\;\;0.5 \cdot \sqrt{re \cdot -4}\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \sqrt{2 \cdot im}\\ \end{array} \]

Alternative 7: 52.4% accurate, 2.0× speedup?

\[\begin{array}{l} \\ 0.5 \cdot \sqrt{2 \cdot im} \end{array} \]
(FPCore (re im) :precision binary64 (* 0.5 (sqrt (* 2.0 im))))
double code(double re, double im) {
	return 0.5 * sqrt((2.0 * im));
}
real(8) function code(re, im)
    real(8), intent (in) :: re
    real(8), intent (in) :: im
    code = 0.5d0 * sqrt((2.0d0 * im))
end function
public static double code(double re, double im) {
	return 0.5 * Math.sqrt((2.0 * im));
}
def code(re, im):
	return 0.5 * math.sqrt((2.0 * im))
function code(re, im)
	return Float64(0.5 * sqrt(Float64(2.0 * im)))
end
function tmp = code(re, im)
	tmp = 0.5 * sqrt((2.0 * im));
end
code[re_, im_] := N[(0.5 * N[Sqrt[N[(2.0 * im), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
0.5 \cdot \sqrt{2 \cdot im}
\end{array}
Derivation
  1. Initial program 37.9%

    \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
  2. Taylor expanded in re around 0 49.6%

    \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot im}} \]
  3. Step-by-step derivation
    1. *-commutative49.6%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{im \cdot 2}} \]
  4. Simplified49.6%

    \[\leadsto 0.5 \cdot \sqrt{\color{blue}{im \cdot 2}} \]
  5. Final simplification49.6%

    \[\leadsto 0.5 \cdot \sqrt{2 \cdot im} \]

Reproduce

?
herbie shell --seed 2023326 
(FPCore (re im)
  :name "math.sqrt on complex, imaginary part, im greater than 0 branch"
  :precision binary64
  :pre (> im 0.0)
  (* 0.5 (sqrt (* 2.0 (- (sqrt (+ (* re re) (* im im))) re)))))