math.sqrt on complex, real part

Percentage Accurate: 41.6% → 83.7%
Time: 8.8s
Alternatives: 5
Speedup: 2.0×

Specification

?
\[\begin{array}{l} \\ 0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \end{array} \]
(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 5 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: 41.6% 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: 83.7% accurate, 0.5× speedup?

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

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

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


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

    1. Initial program 10.0%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \]
    2. Step-by-step derivation
      1. sqr-neg10.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + \color{blue}{\left(-im\right) \cdot \left(-im\right)}} + re\right)} \]
      2. +-commutative10.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \sqrt{re \cdot re + \left(-im\right) \cdot \left(-im\right)}\right)}} \]
      3. sqr-neg10.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{re \cdot re + \color{blue}{im \cdot im}}\right)} \]
      4. +-commutative10.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{im \cdot im + re \cdot re}}\right)} \]
      5. distribute-rgt-in10.0%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 + \sqrt{im \cdot im + re \cdot re} \cdot 2}} \]
      6. cancel-sign-sub10.0%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 - \left(-\sqrt{im \cdot im + re \cdot re}\right) \cdot 2}} \]
      7. distribute-rgt-out--10.0%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot \left(re - \left(-\sqrt{im \cdot im + re \cdot re}\right)\right)}} \]
      8. sub-neg10.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \left(-\left(-\sqrt{im \cdot im + re \cdot re}\right)\right)\right)}} \]
      9. remove-double-neg10.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\sqrt{im \cdot im + re \cdot re}}\right)} \]
      10. +-commutative10.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{re \cdot re + im \cdot im}}\right)} \]
      11. hypot-define17.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\mathsf{hypot}\left(re, im\right)}\right)} \]
    3. Simplified17.0%

      \[\leadsto \color{blue}{0.5 \cdot \sqrt{2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
    4. Add Preprocessing
    5. Step-by-step derivation
      1. hypot-define10.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\sqrt{re \cdot re + im \cdot im}}\right)} \]
      2. distribute-lft-in10.0%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot re + 2 \cdot \sqrt{re \cdot re + im \cdot im}}} \]
      3. +-commutative10.0%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot \sqrt{re \cdot re + im \cdot im} + 2 \cdot re}} \]
      4. *-commutative10.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \sqrt{re \cdot re + im \cdot im} + \color{blue}{re \cdot 2}} \]
      5. add-sqr-sqrt5.5%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\sqrt{2 \cdot \sqrt{re \cdot re + im \cdot im}} \cdot \sqrt{2 \cdot \sqrt{re \cdot re + im \cdot im}}} + re \cdot 2} \]
      6. fma-define2.8%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\mathsf{fma}\left(\sqrt{2 \cdot \sqrt{re \cdot re + im \cdot im}}, \sqrt{2 \cdot \sqrt{re \cdot re + im \cdot im}}, re \cdot 2\right)}} \]
      7. hypot-define2.8%

        \[\leadsto 0.5 \cdot \sqrt{\mathsf{fma}\left(\sqrt{2 \cdot \color{blue}{\mathsf{hypot}\left(re, im\right)}}, \sqrt{2 \cdot \sqrt{re \cdot re + im \cdot im}}, re \cdot 2\right)} \]
      8. hypot-define9.8%

        \[\leadsto 0.5 \cdot \sqrt{\mathsf{fma}\left(\sqrt{2 \cdot \mathsf{hypot}\left(re, im\right)}, \sqrt{2 \cdot \color{blue}{\mathsf{hypot}\left(re, im\right)}}, re \cdot 2\right)} \]
    6. Applied egg-rr9.8%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\mathsf{fma}\left(\sqrt{2 \cdot \mathsf{hypot}\left(re, im\right)}, \sqrt{2 \cdot \mathsf{hypot}\left(re, im\right)}, re \cdot 2\right)}} \]
    7. Taylor expanded in re around -inf 5.0%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{-1 \cdot \left(re \cdot \left(\left(0.5 \cdot \frac{{im}^{2} \cdot {\left(\sqrt{2}\right)}^{2}}{{re}^{2}} + {\left(\sqrt{2}\right)}^{2}\right) - 2\right)\right)}} \]
    8. Step-by-step derivation
      1. mul-1-neg5.0%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{-re \cdot \left(\left(0.5 \cdot \frac{{im}^{2} \cdot {\left(\sqrt{2}\right)}^{2}}{{re}^{2}} + {\left(\sqrt{2}\right)}^{2}\right) - 2\right)}} \]
      2. *-commutative5.0%

        \[\leadsto 0.5 \cdot \sqrt{-\color{blue}{\left(\left(0.5 \cdot \frac{{im}^{2} \cdot {\left(\sqrt{2}\right)}^{2}}{{re}^{2}} + {\left(\sqrt{2}\right)}^{2}\right) - 2\right) \cdot re}} \]
      3. distribute-rgt-neg-in5.0%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\left(\left(0.5 \cdot \frac{{im}^{2} \cdot {\left(\sqrt{2}\right)}^{2}}{{re}^{2}} + {\left(\sqrt{2}\right)}^{2}\right) - 2\right) \cdot \left(-re\right)}} \]
      4. unpow25.0%

        \[\leadsto 0.5 \cdot \sqrt{\left(\left(0.5 \cdot \frac{{im}^{2} \cdot {\left(\sqrt{2}\right)}^{2}}{{re}^{2}} + \color{blue}{\sqrt{2} \cdot \sqrt{2}}\right) - 2\right) \cdot \left(-re\right)} \]
      5. rem-square-sqrt10.0%

        \[\leadsto 0.5 \cdot \sqrt{\left(\left(0.5 \cdot \frac{{im}^{2} \cdot {\left(\sqrt{2}\right)}^{2}}{{re}^{2}} + \color{blue}{2}\right) - 2\right) \cdot \left(-re\right)} \]
      6. associate-+r-40.6%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\left(0.5 \cdot \frac{{im}^{2} \cdot {\left(\sqrt{2}\right)}^{2}}{{re}^{2}} + \left(2 - 2\right)\right)} \cdot \left(-re\right)} \]
      7. unpow240.6%

        \[\leadsto 0.5 \cdot \sqrt{\left(0.5 \cdot \frac{{im}^{2} \cdot \color{blue}{\left(\sqrt{2} \cdot \sqrt{2}\right)}}{{re}^{2}} + \left(2 - 2\right)\right) \cdot \left(-re\right)} \]
      8. rem-square-sqrt40.9%

        \[\leadsto 0.5 \cdot \sqrt{\left(0.5 \cdot \frac{{im}^{2} \cdot \color{blue}{2}}{{re}^{2}} + \left(2 - 2\right)\right) \cdot \left(-re\right)} \]
      9. associate-*r/40.9%

        \[\leadsto 0.5 \cdot \sqrt{\left(0.5 \cdot \color{blue}{\left({im}^{2} \cdot \frac{2}{{re}^{2}}\right)} + \left(2 - 2\right)\right) \cdot \left(-re\right)} \]
      10. metadata-eval40.9%

        \[\leadsto 0.5 \cdot \sqrt{\left(0.5 \cdot \left({im}^{2} \cdot \frac{2}{{re}^{2}}\right) + \color{blue}{0}\right) \cdot \left(-re\right)} \]
    9. Simplified40.9%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\left(0.5 \cdot \left({im}^{2} \cdot \frac{2}{{re}^{2}}\right) + 0\right) \cdot \left(-re\right)}} \]
    10. Step-by-step derivation
      1. +-rgt-identity40.9%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\left(0.5 \cdot \left({im}^{2} \cdot \frac{2}{{re}^{2}}\right)\right)} \cdot \left(-re\right)} \]
      2. distribute-rgt-neg-out40.9%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{-\left(0.5 \cdot \left({im}^{2} \cdot \frac{2}{{re}^{2}}\right)\right) \cdot re}} \]
      3. neg-sub040.9%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{0 - \left(0.5 \cdot \left({im}^{2} \cdot \frac{2}{{re}^{2}}\right)\right) \cdot re}} \]
      4. *-commutative40.9%

        \[\leadsto 0.5 \cdot \sqrt{0 - \color{blue}{\left(\left({im}^{2} \cdot \frac{2}{{re}^{2}}\right) \cdot 0.5\right)} \cdot re} \]
      5. associate-*l*41.0%

        \[\leadsto 0.5 \cdot \sqrt{0 - \color{blue}{\left({im}^{2} \cdot \frac{2}{{re}^{2}}\right) \cdot \left(0.5 \cdot re\right)}} \]
      6. add-sqr-sqrt40.9%

        \[\leadsto 0.5 \cdot \sqrt{0 - \color{blue}{\left(\sqrt{{im}^{2} \cdot \frac{2}{{re}^{2}}} \cdot \sqrt{{im}^{2} \cdot \frac{2}{{re}^{2}}}\right)} \cdot \left(0.5 \cdot re\right)} \]
      7. pow240.9%

        \[\leadsto 0.5 \cdot \sqrt{0 - \color{blue}{{\left(\sqrt{{im}^{2} \cdot \frac{2}{{re}^{2}}}\right)}^{2}} \cdot \left(0.5 \cdot re\right)} \]
      8. sqrt-prod40.9%

        \[\leadsto 0.5 \cdot \sqrt{0 - {\color{blue}{\left(\sqrt{{im}^{2}} \cdot \sqrt{\frac{2}{{re}^{2}}}\right)}}^{2} \cdot \left(0.5 \cdot re\right)} \]
      9. sqrt-pow147.1%

        \[\leadsto 0.5 \cdot \sqrt{0 - {\left(\color{blue}{{im}^{\left(\frac{2}{2}\right)}} \cdot \sqrt{\frac{2}{{re}^{2}}}\right)}^{2} \cdot \left(0.5 \cdot re\right)} \]
      10. metadata-eval47.1%

        \[\leadsto 0.5 \cdot \sqrt{0 - {\left({im}^{\color{blue}{1}} \cdot \sqrt{\frac{2}{{re}^{2}}}\right)}^{2} \cdot \left(0.5 \cdot re\right)} \]
      11. pow147.1%

        \[\leadsto 0.5 \cdot \sqrt{0 - {\left(\color{blue}{im} \cdot \sqrt{\frac{2}{{re}^{2}}}\right)}^{2} \cdot \left(0.5 \cdot re\right)} \]
      12. sqrt-div47.0%

        \[\leadsto 0.5 \cdot \sqrt{0 - {\left(im \cdot \color{blue}{\frac{\sqrt{2}}{\sqrt{{re}^{2}}}}\right)}^{2} \cdot \left(0.5 \cdot re\right)} \]
      13. sqrt-pow155.9%

        \[\leadsto 0.5 \cdot \sqrt{0 - {\left(im \cdot \frac{\sqrt{2}}{\color{blue}{{re}^{\left(\frac{2}{2}\right)}}}\right)}^{2} \cdot \left(0.5 \cdot re\right)} \]
      14. metadata-eval55.9%

        \[\leadsto 0.5 \cdot \sqrt{0 - {\left(im \cdot \frac{\sqrt{2}}{{re}^{\color{blue}{1}}}\right)}^{2} \cdot \left(0.5 \cdot re\right)} \]
      15. pow155.9%

        \[\leadsto 0.5 \cdot \sqrt{0 - {\left(im \cdot \frac{\sqrt{2}}{\color{blue}{re}}\right)}^{2} \cdot \left(0.5 \cdot re\right)} \]
    11. Applied egg-rr55.9%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{0 - {\left(im \cdot \frac{\sqrt{2}}{re}\right)}^{2} \cdot \left(0.5 \cdot re\right)}} \]
    12. Step-by-step derivation
      1. neg-sub055.9%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{-{\left(im \cdot \frac{\sqrt{2}}{re}\right)}^{2} \cdot \left(0.5 \cdot re\right)}} \]
      2. distribute-rgt-neg-in55.9%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{{\left(im \cdot \frac{\sqrt{2}}{re}\right)}^{2} \cdot \left(-0.5 \cdot re\right)}} \]
      3. distribute-lft-neg-in55.9%

        \[\leadsto 0.5 \cdot \sqrt{{\left(im \cdot \frac{\sqrt{2}}{re}\right)}^{2} \cdot \color{blue}{\left(\left(-0.5\right) \cdot re\right)}} \]
      4. metadata-eval55.9%

        \[\leadsto 0.5 \cdot \sqrt{{\left(im \cdot \frac{\sqrt{2}}{re}\right)}^{2} \cdot \left(\color{blue}{-0.5} \cdot re\right)} \]
    13. Simplified55.9%

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

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

    1. Initial program 43.1%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \]
    2. Step-by-step derivation
      1. sqr-neg43.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + \color{blue}{\left(-im\right) \cdot \left(-im\right)}} + re\right)} \]
      2. +-commutative43.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \sqrt{re \cdot re + \left(-im\right) \cdot \left(-im\right)}\right)}} \]
      3. sqr-neg43.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{re \cdot re + \color{blue}{im \cdot im}}\right)} \]
      4. +-commutative43.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{im \cdot im + re \cdot re}}\right)} \]
      5. distribute-rgt-in43.1%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 + \sqrt{im \cdot im + re \cdot re} \cdot 2}} \]
      6. cancel-sign-sub43.1%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 - \left(-\sqrt{im \cdot im + re \cdot re}\right) \cdot 2}} \]
      7. distribute-rgt-out--43.1%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot \left(re - \left(-\sqrt{im \cdot im + re \cdot re}\right)\right)}} \]
      8. sub-neg43.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \left(-\left(-\sqrt{im \cdot im + re \cdot re}\right)\right)\right)}} \]
      9. remove-double-neg43.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\sqrt{im \cdot im + re \cdot re}}\right)} \]
      10. +-commutative43.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{re \cdot re + im \cdot im}}\right)} \]
      11. hypot-define91.2%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\mathsf{hypot}\left(re, im\right)}\right)} \]
    3. Simplified91.2%

      \[\leadsto \color{blue}{0.5 \cdot \sqrt{2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
    4. Add Preprocessing
    5. Step-by-step derivation
      1. *-commutative91.2%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\left(re + \mathsf{hypot}\left(re, im\right)\right) \cdot 2}} \]
      2. hypot-define43.1%

        \[\leadsto 0.5 \cdot \sqrt{\left(re + \color{blue}{\sqrt{re \cdot re + im \cdot im}}\right) \cdot 2} \]
      3. +-commutative43.1%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot 2} \]
      4. *-commutative43.1%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}} \]
      5. add-sqr-sqrt42.8%

        \[\leadsto \color{blue}{\sqrt{0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}} \cdot \sqrt{0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}}} \]
      6. sqrt-unprod43.1%

        \[\leadsto \color{blue}{\sqrt{\left(0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\right) \cdot \left(0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\right)}} \]
      7. *-commutative43.1%

        \[\leadsto \sqrt{\color{blue}{\left(\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot 0.5\right)} \cdot \left(0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\right)} \]
      8. *-commutative43.1%

        \[\leadsto \sqrt{\left(\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot 0.5\right) \cdot \color{blue}{\left(\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot 0.5\right)}} \]
      9. swap-sqr43.1%

        \[\leadsto \sqrt{\color{blue}{\left(\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\right) \cdot \left(0.5 \cdot 0.5\right)}} \]
    6. Applied egg-rr91.2%

      \[\leadsto \color{blue}{\sqrt{\left(2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)\right) \cdot 0.25}} \]
    7. Step-by-step derivation
      1. *-commutative91.2%

        \[\leadsto \sqrt{\color{blue}{0.25 \cdot \left(2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)\right)}} \]
      2. associate-*r*91.2%

        \[\leadsto \sqrt{\color{blue}{\left(0.25 \cdot 2\right) \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
      3. metadata-eval91.2%

        \[\leadsto \sqrt{\color{blue}{0.5} \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)} \]
    8. Simplified91.2%

      \[\leadsto \color{blue}{\sqrt{0.5 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification84.9%

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

Alternative 2: 84.6% accurate, 0.5× speedup?

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

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

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


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (sqrt.f64 (*.f64 #s(literal 2 binary64) (+.f64 (sqrt.f64 (+.f64 (*.f64 re re) (*.f64 im im))) re))) < 0.0

    1. Initial program 12.1%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \]
    2. Step-by-step derivation
      1. sqr-neg12.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + \color{blue}{\left(-im\right) \cdot \left(-im\right)}} + re\right)} \]
      2. +-commutative12.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \sqrt{re \cdot re + \left(-im\right) \cdot \left(-im\right)}\right)}} \]
      3. sqr-neg12.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{re \cdot re + \color{blue}{im \cdot im}}\right)} \]
      4. +-commutative12.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{im \cdot im + re \cdot re}}\right)} \]
      5. distribute-rgt-in12.1%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 + \sqrt{im \cdot im + re \cdot re} \cdot 2}} \]
      6. cancel-sign-sub12.1%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 - \left(-\sqrt{im \cdot im + re \cdot re}\right) \cdot 2}} \]
      7. distribute-rgt-out--12.1%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot \left(re - \left(-\sqrt{im \cdot im + re \cdot re}\right)\right)}} \]
      8. sub-neg12.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \left(-\left(-\sqrt{im \cdot im + re \cdot re}\right)\right)\right)}} \]
      9. remove-double-neg12.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\sqrt{im \cdot im + re \cdot re}}\right)} \]
      10. +-commutative12.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{re \cdot re + im \cdot im}}\right)} \]
      11. hypot-define12.1%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\mathsf{hypot}\left(re, im\right)}\right)} \]
    3. Simplified12.1%

      \[\leadsto \color{blue}{0.5 \cdot \sqrt{2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
    4. Add Preprocessing
    5. Taylor expanded in re around -inf 51.9%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{-1 \cdot \frac{{im}^{2}}{re}}} \]
    6. Step-by-step derivation
      1. mul-1-neg51.9%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{-\frac{{im}^{2}}{re}}} \]
      2. distribute-neg-frac251.9%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\frac{{im}^{2}}{-re}}} \]
    7. Simplified51.9%

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

    if 0.0 < (sqrt.f64 (*.f64 #s(literal 2 binary64) (+.f64 (sqrt.f64 (+.f64 (*.f64 re re) (*.f64 im im))) re)))

    1. Initial program 41.5%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \]
    2. Step-by-step derivation
      1. sqr-neg41.5%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + \color{blue}{\left(-im\right) \cdot \left(-im\right)}} + re\right)} \]
      2. +-commutative41.5%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \sqrt{re \cdot re + \left(-im\right) \cdot \left(-im\right)}\right)}} \]
      3. sqr-neg41.5%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{re \cdot re + \color{blue}{im \cdot im}}\right)} \]
      4. +-commutative41.5%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{im \cdot im + re \cdot re}}\right)} \]
      5. distribute-rgt-in41.5%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 + \sqrt{im \cdot im + re \cdot re} \cdot 2}} \]
      6. cancel-sign-sub41.5%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 - \left(-\sqrt{im \cdot im + re \cdot re}\right) \cdot 2}} \]
      7. distribute-rgt-out--41.5%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot \left(re - \left(-\sqrt{im \cdot im + re \cdot re}\right)\right)}} \]
      8. sub-neg41.5%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \left(-\left(-\sqrt{im \cdot im + re \cdot re}\right)\right)\right)}} \]
      9. remove-double-neg41.5%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\sqrt{im \cdot im + re \cdot re}}\right)} \]
      10. +-commutative41.5%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{re \cdot re + im \cdot im}}\right)} \]
      11. hypot-define89.4%

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

      \[\leadsto \color{blue}{0.5 \cdot \sqrt{2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
    4. Add Preprocessing
    5. Step-by-step derivation
      1. *-commutative89.4%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\left(re + \mathsf{hypot}\left(re, im\right)\right) \cdot 2}} \]
      2. hypot-define41.5%

        \[\leadsto 0.5 \cdot \sqrt{\left(re + \color{blue}{\sqrt{re \cdot re + im \cdot im}}\right) \cdot 2} \]
      3. +-commutative41.5%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot 2} \]
      4. *-commutative41.5%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}} \]
      5. add-sqr-sqrt41.2%

        \[\leadsto \color{blue}{\sqrt{0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}} \cdot \sqrt{0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}}} \]
      6. sqrt-unprod41.5%

        \[\leadsto \color{blue}{\sqrt{\left(0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\right) \cdot \left(0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\right)}} \]
      7. *-commutative41.5%

        \[\leadsto \sqrt{\color{blue}{\left(\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot 0.5\right)} \cdot \left(0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\right)} \]
      8. *-commutative41.5%

        \[\leadsto \sqrt{\left(\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot 0.5\right) \cdot \color{blue}{\left(\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot 0.5\right)}} \]
      9. swap-sqr41.5%

        \[\leadsto \sqrt{\color{blue}{\left(\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\right) \cdot \left(0.5 \cdot 0.5\right)}} \]
    6. Applied egg-rr89.4%

      \[\leadsto \color{blue}{\sqrt{\left(2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)\right) \cdot 0.25}} \]
    7. Step-by-step derivation
      1. *-commutative89.4%

        \[\leadsto \sqrt{\color{blue}{0.25 \cdot \left(2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)\right)}} \]
      2. associate-*r*89.4%

        \[\leadsto \sqrt{\color{blue}{\left(0.25 \cdot 2\right) \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
      3. metadata-eval89.4%

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

      \[\leadsto \color{blue}{\sqrt{0.5 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification83.8%

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

Alternative 3: 79.3% accurate, 1.0× speedup?

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

\\
\sqrt{0.5 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}
\end{array}
Derivation
  1. Initial program 37.1%

    \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \]
  2. Step-by-step derivation
    1. sqr-neg37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + \color{blue}{\left(-im\right) \cdot \left(-im\right)}} + re\right)} \]
    2. +-commutative37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \sqrt{re \cdot re + \left(-im\right) \cdot \left(-im\right)}\right)}} \]
    3. sqr-neg37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{re \cdot re + \color{blue}{im \cdot im}}\right)} \]
    4. +-commutative37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{im \cdot im + re \cdot re}}\right)} \]
    5. distribute-rgt-in37.1%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 + \sqrt{im \cdot im + re \cdot re} \cdot 2}} \]
    6. cancel-sign-sub37.1%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 - \left(-\sqrt{im \cdot im + re \cdot re}\right) \cdot 2}} \]
    7. distribute-rgt-out--37.1%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot \left(re - \left(-\sqrt{im \cdot im + re \cdot re}\right)\right)}} \]
    8. sub-neg37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \left(-\left(-\sqrt{im \cdot im + re \cdot re}\right)\right)\right)}} \]
    9. remove-double-neg37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\sqrt{im \cdot im + re \cdot re}}\right)} \]
    10. +-commutative37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{re \cdot re + im \cdot im}}\right)} \]
    11. hypot-define77.9%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\mathsf{hypot}\left(re, im\right)}\right)} \]
  3. Simplified77.9%

    \[\leadsto \color{blue}{0.5 \cdot \sqrt{2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
  4. Add Preprocessing
  5. Step-by-step derivation
    1. *-commutative77.9%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\left(re + \mathsf{hypot}\left(re, im\right)\right) \cdot 2}} \]
    2. hypot-define37.1%

      \[\leadsto 0.5 \cdot \sqrt{\left(re + \color{blue}{\sqrt{re \cdot re + im \cdot im}}\right) \cdot 2} \]
    3. +-commutative37.1%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot 2} \]
    4. *-commutative37.1%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}} \]
    5. add-sqr-sqrt36.9%

      \[\leadsto \color{blue}{\sqrt{0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}} \cdot \sqrt{0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}}} \]
    6. sqrt-unprod37.1%

      \[\leadsto \color{blue}{\sqrt{\left(0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\right) \cdot \left(0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\right)}} \]
    7. *-commutative37.1%

      \[\leadsto \sqrt{\color{blue}{\left(\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot 0.5\right)} \cdot \left(0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\right)} \]
    8. *-commutative37.1%

      \[\leadsto \sqrt{\left(\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot 0.5\right) \cdot \color{blue}{\left(\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot 0.5\right)}} \]
    9. swap-sqr37.1%

      \[\leadsto \sqrt{\color{blue}{\left(\sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\right) \cdot \left(0.5 \cdot 0.5\right)}} \]
  6. Applied egg-rr77.9%

    \[\leadsto \color{blue}{\sqrt{\left(2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)\right) \cdot 0.25}} \]
  7. Step-by-step derivation
    1. *-commutative77.9%

      \[\leadsto \sqrt{\color{blue}{0.25 \cdot \left(2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)\right)}} \]
    2. associate-*r*77.9%

      \[\leadsto \sqrt{\color{blue}{\left(0.25 \cdot 2\right) \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
    3. metadata-eval77.9%

      \[\leadsto \sqrt{\color{blue}{0.5} \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)} \]
  8. Simplified77.9%

    \[\leadsto \color{blue}{\sqrt{0.5 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
  9. Add Preprocessing

Alternative 4: 42.1% accurate, 2.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;re \leq 1.4 \cdot 10^{-13}:\\ \;\;\;\;\sqrt{im \cdot 0.5}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{re}\\ \end{array} \end{array} \]
(FPCore (re im)
 :precision binary64
 (if (<= re 1.4e-13) (sqrt (* im 0.5)) (sqrt re)))
double code(double re, double im) {
	double tmp;
	if (re <= 1.4e-13) {
		tmp = sqrt((im * 0.5));
	} else {
		tmp = sqrt(re);
	}
	return tmp;
}
real(8) function code(re, im)
    real(8), intent (in) :: re
    real(8), intent (in) :: im
    real(8) :: tmp
    if (re <= 1.4d-13) then
        tmp = sqrt((im * 0.5d0))
    else
        tmp = sqrt(re)
    end if
    code = tmp
end function
public static double code(double re, double im) {
	double tmp;
	if (re <= 1.4e-13) {
		tmp = Math.sqrt((im * 0.5));
	} else {
		tmp = Math.sqrt(re);
	}
	return tmp;
}
def code(re, im):
	tmp = 0
	if re <= 1.4e-13:
		tmp = math.sqrt((im * 0.5))
	else:
		tmp = math.sqrt(re)
	return tmp
function code(re, im)
	tmp = 0.0
	if (re <= 1.4e-13)
		tmp = sqrt(Float64(im * 0.5));
	else
		tmp = sqrt(re);
	end
	return tmp
end
function tmp_2 = code(re, im)
	tmp = 0.0;
	if (re <= 1.4e-13)
		tmp = sqrt((im * 0.5));
	else
		tmp = sqrt(re);
	end
	tmp_2 = tmp;
end
code[re_, im_] := If[LessEqual[re, 1.4e-13], N[Sqrt[N[(im * 0.5), $MachinePrecision]], $MachinePrecision], N[Sqrt[re], $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;re \leq 1.4 \cdot 10^{-13}:\\
\;\;\;\;\sqrt{im \cdot 0.5}\\

\mathbf{else}:\\
\;\;\;\;\sqrt{re}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if re < 1.4000000000000001e-13

    1. Initial program 37.0%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \]
    2. Step-by-step derivation
      1. sqr-neg37.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + \color{blue}{\left(-im\right) \cdot \left(-im\right)}} + re\right)} \]
      2. +-commutative37.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \sqrt{re \cdot re + \left(-im\right) \cdot \left(-im\right)}\right)}} \]
      3. sqr-neg37.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{re \cdot re + \color{blue}{im \cdot im}}\right)} \]
      4. +-commutative37.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{im \cdot im + re \cdot re}}\right)} \]
      5. distribute-rgt-in37.0%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 + \sqrt{im \cdot im + re \cdot re} \cdot 2}} \]
      6. cancel-sign-sub37.0%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 - \left(-\sqrt{im \cdot im + re \cdot re}\right) \cdot 2}} \]
      7. distribute-rgt-out--37.0%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot \left(re - \left(-\sqrt{im \cdot im + re \cdot re}\right)\right)}} \]
      8. sub-neg37.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \left(-\left(-\sqrt{im \cdot im + re \cdot re}\right)\right)\right)}} \]
      9. remove-double-neg37.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\sqrt{im \cdot im + re \cdot re}}\right)} \]
      10. +-commutative37.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{re \cdot re + im \cdot im}}\right)} \]
      11. hypot-define70.2%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\mathsf{hypot}\left(re, im\right)}\right)} \]
    3. Simplified70.2%

      \[\leadsto \color{blue}{0.5 \cdot \sqrt{2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
    4. Add Preprocessing
    5. Taylor expanded in re around 0 29.0%

      \[\leadsto \color{blue}{0.5 \cdot \left(\sqrt{im} \cdot \sqrt{2}\right)} \]
    6. Step-by-step derivation
      1. associate-*r*29.0%

        \[\leadsto \color{blue}{\left(0.5 \cdot \sqrt{im}\right) \cdot \sqrt{2}} \]
    7. Simplified29.0%

      \[\leadsto \color{blue}{\left(0.5 \cdot \sqrt{im}\right) \cdot \sqrt{2}} \]
    8. Step-by-step derivation
      1. add-sqr-sqrt28.8%

        \[\leadsto \color{blue}{\sqrt{\left(0.5 \cdot \sqrt{im}\right) \cdot \sqrt{2}} \cdot \sqrt{\left(0.5 \cdot \sqrt{im}\right) \cdot \sqrt{2}}} \]
      2. pow228.8%

        \[\leadsto \color{blue}{{\left(\sqrt{\left(0.5 \cdot \sqrt{im}\right) \cdot \sqrt{2}}\right)}^{2}} \]
      3. associate-*l*28.8%

        \[\leadsto {\left(\sqrt{\color{blue}{0.5 \cdot \left(\sqrt{im} \cdot \sqrt{2}\right)}}\right)}^{2} \]
      4. sqrt-unprod28.9%

        \[\leadsto {\left(\sqrt{0.5 \cdot \color{blue}{\sqrt{im \cdot 2}}}\right)}^{2} \]
    9. Applied egg-rr28.9%

      \[\leadsto \color{blue}{{\left(\sqrt{0.5 \cdot \sqrt{im \cdot 2}}\right)}^{2}} \]
    10. Step-by-step derivation
      1. unpow228.9%

        \[\leadsto \color{blue}{\sqrt{0.5 \cdot \sqrt{im \cdot 2}} \cdot \sqrt{0.5 \cdot \sqrt{im \cdot 2}}} \]
      2. sqrt-unprod29.2%

        \[\leadsto \color{blue}{\sqrt{\left(0.5 \cdot \sqrt{im \cdot 2}\right) \cdot \left(0.5 \cdot \sqrt{im \cdot 2}\right)}} \]
      3. *-commutative29.2%

        \[\leadsto \sqrt{\color{blue}{\left(\sqrt{im \cdot 2} \cdot 0.5\right)} \cdot \left(0.5 \cdot \sqrt{im \cdot 2}\right)} \]
      4. *-commutative29.2%

        \[\leadsto \sqrt{\left(\sqrt{im \cdot 2} \cdot 0.5\right) \cdot \color{blue}{\left(\sqrt{im \cdot 2} \cdot 0.5\right)}} \]
      5. swap-sqr29.2%

        \[\leadsto \sqrt{\color{blue}{\left(\sqrt{im \cdot 2} \cdot \sqrt{im \cdot 2}\right) \cdot \left(0.5 \cdot 0.5\right)}} \]
      6. add-sqr-sqrt29.2%

        \[\leadsto \sqrt{\color{blue}{\left(im \cdot 2\right)} \cdot \left(0.5 \cdot 0.5\right)} \]
      7. metadata-eval29.2%

        \[\leadsto \sqrt{\left(im \cdot 2\right) \cdot \color{blue}{0.25}} \]
    11. Applied egg-rr29.2%

      \[\leadsto \color{blue}{\sqrt{\left(im \cdot 2\right) \cdot 0.25}} \]
    12. Step-by-step derivation
      1. associate-*l*29.2%

        \[\leadsto \sqrt{\color{blue}{im \cdot \left(2 \cdot 0.25\right)}} \]
      2. metadata-eval29.2%

        \[\leadsto \sqrt{im \cdot \color{blue}{0.5}} \]
    13. Simplified29.2%

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

    if 1.4000000000000001e-13 < re

    1. Initial program 37.6%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \]
    2. Step-by-step derivation
      1. sqr-neg37.6%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + \color{blue}{\left(-im\right) \cdot \left(-im\right)}} + re\right)} \]
      2. +-commutative37.6%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \sqrt{re \cdot re + \left(-im\right) \cdot \left(-im\right)}\right)}} \]
      3. sqr-neg37.6%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{re \cdot re + \color{blue}{im \cdot im}}\right)} \]
      4. +-commutative37.6%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{im \cdot im + re \cdot re}}\right)} \]
      5. distribute-rgt-in37.6%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 + \sqrt{im \cdot im + re \cdot re} \cdot 2}} \]
      6. cancel-sign-sub37.6%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 - \left(-\sqrt{im \cdot im + re \cdot re}\right) \cdot 2}} \]
      7. distribute-rgt-out--37.6%

        \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot \left(re - \left(-\sqrt{im \cdot im + re \cdot re}\right)\right)}} \]
      8. sub-neg37.6%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \left(-\left(-\sqrt{im \cdot im + re \cdot re}\right)\right)\right)}} \]
      9. remove-double-neg37.6%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\sqrt{im \cdot im + re \cdot re}}\right)} \]
      10. +-commutative37.6%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{re \cdot re + im \cdot im}}\right)} \]
      11. hypot-define100.0%

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\mathsf{hypot}\left(re, im\right)}\right)} \]
    3. Simplified100.0%

      \[\leadsto \color{blue}{0.5 \cdot \sqrt{2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
    4. Add Preprocessing
    5. Taylor expanded in re around inf 74.8%

      \[\leadsto \color{blue}{0.5 \cdot \left(\sqrt{re} \cdot {\left(\sqrt{2}\right)}^{2}\right)} \]
    6. Step-by-step derivation
      1. *-commutative74.8%

        \[\leadsto 0.5 \cdot \color{blue}{\left({\left(\sqrt{2}\right)}^{2} \cdot \sqrt{re}\right)} \]
      2. unpow274.8%

        \[\leadsto 0.5 \cdot \left(\color{blue}{\left(\sqrt{2} \cdot \sqrt{2}\right)} \cdot \sqrt{re}\right) \]
      3. rem-square-sqrt76.3%

        \[\leadsto 0.5 \cdot \left(\color{blue}{2} \cdot \sqrt{re}\right) \]
      4. associate-*r*76.3%

        \[\leadsto \color{blue}{\left(0.5 \cdot 2\right) \cdot \sqrt{re}} \]
      5. metadata-eval76.3%

        \[\leadsto \color{blue}{1} \cdot \sqrt{re} \]
    7. Simplified76.3%

      \[\leadsto \color{blue}{1 \cdot \sqrt{re}} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification41.3%

    \[\leadsto \begin{array}{l} \mathbf{if}\;re \leq 1.4 \cdot 10^{-13}:\\ \;\;\;\;\sqrt{im \cdot 0.5}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{re}\\ \end{array} \]
  5. Add Preprocessing

Alternative 5: 26.2% accurate, 2.1× speedup?

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

\\
\sqrt{im \cdot 0.5}
\end{array}
Derivation
  1. Initial program 37.1%

    \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)} \]
  2. Step-by-step derivation
    1. sqr-neg37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + \color{blue}{\left(-im\right) \cdot \left(-im\right)}} + re\right)} \]
    2. +-commutative37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \sqrt{re \cdot re + \left(-im\right) \cdot \left(-im\right)}\right)}} \]
    3. sqr-neg37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{re \cdot re + \color{blue}{im \cdot im}}\right)} \]
    4. +-commutative37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{im \cdot im + re \cdot re}}\right)} \]
    5. distribute-rgt-in37.1%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 + \sqrt{im \cdot im + re \cdot re} \cdot 2}} \]
    6. cancel-sign-sub37.1%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{re \cdot 2 - \left(-\sqrt{im \cdot im + re \cdot re}\right) \cdot 2}} \]
    7. distribute-rgt-out--37.1%

      \[\leadsto 0.5 \cdot \sqrt{\color{blue}{2 \cdot \left(re - \left(-\sqrt{im \cdot im + re \cdot re}\right)\right)}} \]
    8. sub-neg37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(re + \left(-\left(-\sqrt{im \cdot im + re \cdot re}\right)\right)\right)}} \]
    9. remove-double-neg37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\sqrt{im \cdot im + re \cdot re}}\right)} \]
    10. +-commutative37.1%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \sqrt{\color{blue}{re \cdot re + im \cdot im}}\right)} \]
    11. hypot-define77.9%

      \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(re + \color{blue}{\mathsf{hypot}\left(re, im\right)}\right)} \]
  3. Simplified77.9%

    \[\leadsto \color{blue}{0.5 \cdot \sqrt{2 \cdot \left(re + \mathsf{hypot}\left(re, im\right)\right)}} \]
  4. Add Preprocessing
  5. Taylor expanded in re around 0 25.2%

    \[\leadsto \color{blue}{0.5 \cdot \left(\sqrt{im} \cdot \sqrt{2}\right)} \]
  6. Step-by-step derivation
    1. associate-*r*25.2%

      \[\leadsto \color{blue}{\left(0.5 \cdot \sqrt{im}\right) \cdot \sqrt{2}} \]
  7. Simplified25.2%

    \[\leadsto \color{blue}{\left(0.5 \cdot \sqrt{im}\right) \cdot \sqrt{2}} \]
  8. Step-by-step derivation
    1. add-sqr-sqrt25.1%

      \[\leadsto \color{blue}{\sqrt{\left(0.5 \cdot \sqrt{im}\right) \cdot \sqrt{2}} \cdot \sqrt{\left(0.5 \cdot \sqrt{im}\right) \cdot \sqrt{2}}} \]
    2. pow225.1%

      \[\leadsto \color{blue}{{\left(\sqrt{\left(0.5 \cdot \sqrt{im}\right) \cdot \sqrt{2}}\right)}^{2}} \]
    3. associate-*l*25.1%

      \[\leadsto {\left(\sqrt{\color{blue}{0.5 \cdot \left(\sqrt{im} \cdot \sqrt{2}\right)}}\right)}^{2} \]
    4. sqrt-unprod25.2%

      \[\leadsto {\left(\sqrt{0.5 \cdot \color{blue}{\sqrt{im \cdot 2}}}\right)}^{2} \]
  9. Applied egg-rr25.2%

    \[\leadsto \color{blue}{{\left(\sqrt{0.5 \cdot \sqrt{im \cdot 2}}\right)}^{2}} \]
  10. Step-by-step derivation
    1. unpow225.2%

      \[\leadsto \color{blue}{\sqrt{0.5 \cdot \sqrt{im \cdot 2}} \cdot \sqrt{0.5 \cdot \sqrt{im \cdot 2}}} \]
    2. sqrt-unprod25.4%

      \[\leadsto \color{blue}{\sqrt{\left(0.5 \cdot \sqrt{im \cdot 2}\right) \cdot \left(0.5 \cdot \sqrt{im \cdot 2}\right)}} \]
    3. *-commutative25.4%

      \[\leadsto \sqrt{\color{blue}{\left(\sqrt{im \cdot 2} \cdot 0.5\right)} \cdot \left(0.5 \cdot \sqrt{im \cdot 2}\right)} \]
    4. *-commutative25.4%

      \[\leadsto \sqrt{\left(\sqrt{im \cdot 2} \cdot 0.5\right) \cdot \color{blue}{\left(\sqrt{im \cdot 2} \cdot 0.5\right)}} \]
    5. swap-sqr25.4%

      \[\leadsto \sqrt{\color{blue}{\left(\sqrt{im \cdot 2} \cdot \sqrt{im \cdot 2}\right) \cdot \left(0.5 \cdot 0.5\right)}} \]
    6. add-sqr-sqrt25.4%

      \[\leadsto \sqrt{\color{blue}{\left(im \cdot 2\right)} \cdot \left(0.5 \cdot 0.5\right)} \]
    7. metadata-eval25.4%

      \[\leadsto \sqrt{\left(im \cdot 2\right) \cdot \color{blue}{0.25}} \]
  11. Applied egg-rr25.4%

    \[\leadsto \color{blue}{\sqrt{\left(im \cdot 2\right) \cdot 0.25}} \]
  12. Step-by-step derivation
    1. associate-*l*25.4%

      \[\leadsto \sqrt{\color{blue}{im \cdot \left(2 \cdot 0.25\right)}} \]
    2. metadata-eval25.4%

      \[\leadsto \sqrt{im \cdot \color{blue}{0.5}} \]
  13. Simplified25.4%

    \[\leadsto \color{blue}{\sqrt{im \cdot 0.5}} \]
  14. Add Preprocessing

Developer target: 48.6% accurate, 0.7× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \sqrt{re \cdot re + im \cdot im}\\ \mathbf{if}\;re < 0:\\ \;\;\;\;0.5 \cdot \left(\sqrt{2} \cdot \sqrt{\frac{im \cdot im}{t\_0 - re}}\right)\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \sqrt{2 \cdot \left(t\_0 + re\right)}\\ \end{array} \end{array} \]
(FPCore (re im)
 :precision binary64
 (let* ((t_0 (sqrt (+ (* re re) (* im im)))))
   (if (< re 0.0)
     (* 0.5 (* (sqrt 2.0) (sqrt (/ (* im im) (- t_0 re)))))
     (* 0.5 (sqrt (* 2.0 (+ t_0 re)))))))
double code(double re, double im) {
	double t_0 = sqrt(((re * re) + (im * im)));
	double tmp;
	if (re < 0.0) {
		tmp = 0.5 * (sqrt(2.0) * sqrt(((im * im) / (t_0 - re))));
	} else {
		tmp = 0.5 * sqrt((2.0 * (t_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) :: tmp
    t_0 = sqrt(((re * re) + (im * im)))
    if (re < 0.0d0) then
        tmp = 0.5d0 * (sqrt(2.0d0) * sqrt(((im * im) / (t_0 - re))))
    else
        tmp = 0.5d0 * sqrt((2.0d0 * (t_0 + re)))
    end if
    code = tmp
end function
public static double code(double re, double im) {
	double t_0 = Math.sqrt(((re * re) + (im * im)));
	double tmp;
	if (re < 0.0) {
		tmp = 0.5 * (Math.sqrt(2.0) * Math.sqrt(((im * im) / (t_0 - re))));
	} else {
		tmp = 0.5 * Math.sqrt((2.0 * (t_0 + re)));
	}
	return tmp;
}
def code(re, im):
	t_0 = math.sqrt(((re * re) + (im * im)))
	tmp = 0
	if re < 0.0:
		tmp = 0.5 * (math.sqrt(2.0) * math.sqrt(((im * im) / (t_0 - re))))
	else:
		tmp = 0.5 * math.sqrt((2.0 * (t_0 + re)))
	return tmp
function code(re, im)
	t_0 = sqrt(Float64(Float64(re * re) + Float64(im * im)))
	tmp = 0.0
	if (re < 0.0)
		tmp = Float64(0.5 * Float64(sqrt(2.0) * sqrt(Float64(Float64(im * im) / Float64(t_0 - re)))));
	else
		tmp = Float64(0.5 * sqrt(Float64(2.0 * Float64(t_0 + re))));
	end
	return tmp
end
function tmp_2 = code(re, im)
	t_0 = sqrt(((re * re) + (im * im)));
	tmp = 0.0;
	if (re < 0.0)
		tmp = 0.5 * (sqrt(2.0) * sqrt(((im * im) / (t_0 - re))));
	else
		tmp = 0.5 * sqrt((2.0 * (t_0 + re)));
	end
	tmp_2 = tmp;
end
code[re_, im_] := Block[{t$95$0 = N[Sqrt[N[(N[(re * re), $MachinePrecision] + N[(im * im), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]}, If[Less[re, 0.0], N[(0.5 * N[(N[Sqrt[2.0], $MachinePrecision] * N[Sqrt[N[(N[(im * im), $MachinePrecision] / N[(t$95$0 - re), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(0.5 * N[Sqrt[N[(2.0 * N[(t$95$0 + re), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \sqrt{re \cdot re + im \cdot im}\\
\mathbf{if}\;re < 0:\\
\;\;\;\;0.5 \cdot \left(\sqrt{2} \cdot \sqrt{\frac{im \cdot im}{t\_0 - re}}\right)\\

\mathbf{else}:\\
\;\;\;\;0.5 \cdot \sqrt{2 \cdot \left(t\_0 + re\right)}\\


\end{array}
\end{array}

Reproduce

?
herbie shell --seed 2024101 
(FPCore (re im)
  :name "math.sqrt on complex, real part"
  :precision binary64

  :alt
  (if (< re 0.0) (* 0.5 (* (sqrt 2.0) (sqrt (/ (* im im) (- (sqrt (+ (* re re) (* im im))) re))))) (* 0.5 (sqrt (* 2.0 (+ (sqrt (+ (* re re) (* im im))) re)))))

  (* 0.5 (sqrt (* 2.0 (+ (sqrt (+ (* re re) (* im im))) re)))))