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

Percentage Accurate: 41.4% → 87.7%
Time: 7.5s
Alternatives: 8
Speedup: 1.7×

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 8 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: 41.4% 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: 87.7% accurate, 0.4× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;re \leq 5.7 \cdot 10^{-70}:\\ \;\;\;\;\sqrt{\left(\mathsf{hypot}\left(re, im\right) - re\right) \cdot 2} \cdot 0.5\\ \mathbf{else}:\\ \;\;\;\;\sqrt{\frac{1}{re}} \cdot \left(im \cdot 0.5\right)\\ \end{array} \end{array} \]
(FPCore (re im)
 :precision binary64
 (if (<= re 5.7e-70)
   (* (sqrt (* (- (hypot re im) re) 2.0)) 0.5)
   (* (sqrt (/ 1.0 re)) (* im 0.5))))
double code(double re, double im) {
	double tmp;
	if (re <= 5.7e-70) {
		tmp = sqrt(((hypot(re, im) - re) * 2.0)) * 0.5;
	} else {
		tmp = sqrt((1.0 / re)) * (im * 0.5);
	}
	return tmp;
}
public static double code(double re, double im) {
	double tmp;
	if (re <= 5.7e-70) {
		tmp = Math.sqrt(((Math.hypot(re, im) - re) * 2.0)) * 0.5;
	} else {
		tmp = Math.sqrt((1.0 / re)) * (im * 0.5);
	}
	return tmp;
}
def code(re, im):
	tmp = 0
	if re <= 5.7e-70:
		tmp = math.sqrt(((math.hypot(re, im) - re) * 2.0)) * 0.5
	else:
		tmp = math.sqrt((1.0 / re)) * (im * 0.5)
	return tmp
function code(re, im)
	tmp = 0.0
	if (re <= 5.7e-70)
		tmp = Float64(sqrt(Float64(Float64(hypot(re, im) - re) * 2.0)) * 0.5);
	else
		tmp = Float64(sqrt(Float64(1.0 / re)) * Float64(im * 0.5));
	end
	return tmp
end
function tmp_2 = code(re, im)
	tmp = 0.0;
	if (re <= 5.7e-70)
		tmp = sqrt(((hypot(re, im) - re) * 2.0)) * 0.5;
	else
		tmp = sqrt((1.0 / re)) * (im * 0.5);
	end
	tmp_2 = tmp;
end
code[re_, im_] := If[LessEqual[re, 5.7e-70], N[(N[Sqrt[N[(N[(N[Sqrt[re ^ 2 + im ^ 2], $MachinePrecision] - re), $MachinePrecision] * 2.0), $MachinePrecision]], $MachinePrecision] * 0.5), $MachinePrecision], N[(N[Sqrt[N[(1.0 / re), $MachinePrecision]], $MachinePrecision] * N[(im * 0.5), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;re \leq 5.7 \cdot 10^{-70}:\\
\;\;\;\;\sqrt{\left(\mathsf{hypot}\left(re, im\right) - re\right) \cdot 2} \cdot 0.5\\

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


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if re < 5.70000000000000028e-70

    1. Initial program 58.7%

      \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
    2. Add Preprocessing
    3. Step-by-step derivation
      1. lift-sqrt.f64N/A

        \[\leadsto \frac{1}{2} \cdot \sqrt{2 \cdot \left(\color{blue}{\sqrt{re \cdot re + im \cdot im}} - re\right)} \]
      2. lift-+.f64N/A

        \[\leadsto \frac{1}{2} \cdot \sqrt{2 \cdot \left(\sqrt{\color{blue}{re \cdot re + im \cdot im}} - re\right)} \]
      3. lift-*.f64N/A

        \[\leadsto \frac{1}{2} \cdot \sqrt{2 \cdot \left(\sqrt{\color{blue}{re \cdot re} + im \cdot im} - re\right)} \]
      4. lift-*.f64N/A

        \[\leadsto \frac{1}{2} \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + \color{blue}{im \cdot im}} - re\right)} \]
      5. lower-hypot.f6498.9

        \[\leadsto 0.5 \cdot \sqrt{2 \cdot \left(\color{blue}{\mathsf{hypot}\left(re, im\right)} - re\right)} \]
    4. Applied rewrites98.9%

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

    if 5.70000000000000028e-70 < re

    1. Initial program 12.0%

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

      \[\leadsto \color{blue}{\frac{1}{2} \cdot \left(\left(im \cdot \left(\sqrt{\frac{1}{2}} \cdot \sqrt{2}\right)\right) \cdot \sqrt{\frac{1}{re}}\right)} \]
    4. Step-by-step derivation
      1. associate-*r*N/A

        \[\leadsto \color{blue}{\left(\frac{1}{2} \cdot \left(im \cdot \left(\sqrt{\frac{1}{2}} \cdot \sqrt{2}\right)\right)\right) \cdot \sqrt{\frac{1}{re}}} \]
      2. lower-*.f64N/A

        \[\leadsto \color{blue}{\left(\frac{1}{2} \cdot \left(im \cdot \left(\sqrt{\frac{1}{2}} \cdot \sqrt{2}\right)\right)\right) \cdot \sqrt{\frac{1}{re}}} \]
      3. associate-*r*N/A

        \[\leadsto \left(\frac{1}{2} \cdot \color{blue}{\left(\left(im \cdot \sqrt{\frac{1}{2}}\right) \cdot \sqrt{2}\right)}\right) \cdot \sqrt{\frac{1}{re}} \]
      4. associate-*r*N/A

        \[\leadsto \color{blue}{\left(\left(\frac{1}{2} \cdot \left(im \cdot \sqrt{\frac{1}{2}}\right)\right) \cdot \sqrt{2}\right)} \cdot \sqrt{\frac{1}{re}} \]
      5. lower-*.f64N/A

        \[\leadsto \color{blue}{\left(\left(\frac{1}{2} \cdot \left(im \cdot \sqrt{\frac{1}{2}}\right)\right) \cdot \sqrt{2}\right)} \cdot \sqrt{\frac{1}{re}} \]
      6. lower-*.f64N/A

        \[\leadsto \left(\color{blue}{\left(\frac{1}{2} \cdot \left(im \cdot \sqrt{\frac{1}{2}}\right)\right)} \cdot \sqrt{2}\right) \cdot \sqrt{\frac{1}{re}} \]
      7. lower-*.f64N/A

        \[\leadsto \left(\left(\frac{1}{2} \cdot \color{blue}{\left(im \cdot \sqrt{\frac{1}{2}}\right)}\right) \cdot \sqrt{2}\right) \cdot \sqrt{\frac{1}{re}} \]
      8. lower-sqrt.f64N/A

        \[\leadsto \left(\left(\frac{1}{2} \cdot \left(im \cdot \color{blue}{\sqrt{\frac{1}{2}}}\right)\right) \cdot \sqrt{2}\right) \cdot \sqrt{\frac{1}{re}} \]
      9. lower-sqrt.f64N/A

        \[\leadsto \left(\left(\frac{1}{2} \cdot \left(im \cdot \sqrt{\frac{1}{2}}\right)\right) \cdot \color{blue}{\sqrt{2}}\right) \cdot \sqrt{\frac{1}{re}} \]
      10. lower-sqrt.f64N/A

        \[\leadsto \left(\left(\frac{1}{2} \cdot \left(im \cdot \sqrt{\frac{1}{2}}\right)\right) \cdot \sqrt{2}\right) \cdot \color{blue}{\sqrt{\frac{1}{re}}} \]
      11. lower-/.f6479.7

        \[\leadsto \left(\left(0.5 \cdot \left(im \cdot \sqrt{0.5}\right)\right) \cdot \sqrt{2}\right) \cdot \sqrt{\color{blue}{\frac{1}{re}}} \]
    5. Applied rewrites79.7%

      \[\leadsto \color{blue}{\left(\left(0.5 \cdot \left(im \cdot \sqrt{0.5}\right)\right) \cdot \sqrt{2}\right) \cdot \sqrt{\frac{1}{re}}} \]
    6. Step-by-step derivation
      1. Applied rewrites80.4%

        \[\leadsto \left(im \cdot 0.5\right) \cdot \sqrt{\color{blue}{\frac{1}{re}}} \]
    7. Recombined 2 regimes into one program.
    8. Final simplification93.0%

      \[\leadsto \begin{array}{l} \mathbf{if}\;re \leq 5.7 \cdot 10^{-70}:\\ \;\;\;\;\sqrt{\left(\mathsf{hypot}\left(re, im\right) - re\right) \cdot 2} \cdot 0.5\\ \mathbf{else}:\\ \;\;\;\;\sqrt{\frac{1}{re}} \cdot \left(im \cdot 0.5\right)\\ \end{array} \]
    9. Add Preprocessing

    Alternative 2: 78.5% accurate, 0.8× speedup?

    \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;re \leq -2.7 \cdot 10^{+145}:\\ \;\;\;\;\sqrt{-4 \cdot re} \cdot 0.5\\ \mathbf{elif}\;re \leq -3 \cdot 10^{-151}:\\ \;\;\;\;\sqrt{\left(\sqrt{im \cdot im + re \cdot re} - re\right) \cdot 2} \cdot 0.5\\ \mathbf{elif}\;re \leq 5.7 \cdot 10^{-70}:\\ \;\;\;\;\sqrt{\left(im - re\right) \cdot 2} \cdot 0.5\\ \mathbf{else}:\\ \;\;\;\;\sqrt{\frac{1}{re}} \cdot \left(im \cdot 0.5\right)\\ \end{array} \end{array} \]
    (FPCore (re im)
     :precision binary64
     (if (<= re -2.7e+145)
       (* (sqrt (* -4.0 re)) 0.5)
       (if (<= re -3e-151)
         (* (sqrt (* (- (sqrt (+ (* im im) (* re re))) re) 2.0)) 0.5)
         (if (<= re 5.7e-70)
           (* (sqrt (* (- im re) 2.0)) 0.5)
           (* (sqrt (/ 1.0 re)) (* im 0.5))))))
    double code(double re, double im) {
    	double tmp;
    	if (re <= -2.7e+145) {
    		tmp = sqrt((-4.0 * re)) * 0.5;
    	} else if (re <= -3e-151) {
    		tmp = sqrt(((sqrt(((im * im) + (re * re))) - re) * 2.0)) * 0.5;
    	} else if (re <= 5.7e-70) {
    		tmp = sqrt(((im - re) * 2.0)) * 0.5;
    	} else {
    		tmp = sqrt((1.0 / re)) * (im * 0.5);
    	}
    	return tmp;
    }
    
    real(8) function code(re, im)
        real(8), intent (in) :: re
        real(8), intent (in) :: im
        real(8) :: tmp
        if (re <= (-2.7d+145)) then
            tmp = sqrt(((-4.0d0) * re)) * 0.5d0
        else if (re <= (-3d-151)) then
            tmp = sqrt(((sqrt(((im * im) + (re * re))) - re) * 2.0d0)) * 0.5d0
        else if (re <= 5.7d-70) then
            tmp = sqrt(((im - re) * 2.0d0)) * 0.5d0
        else
            tmp = sqrt((1.0d0 / re)) * (im * 0.5d0)
        end if
        code = tmp
    end function
    
    public static double code(double re, double im) {
    	double tmp;
    	if (re <= -2.7e+145) {
    		tmp = Math.sqrt((-4.0 * re)) * 0.5;
    	} else if (re <= -3e-151) {
    		tmp = Math.sqrt(((Math.sqrt(((im * im) + (re * re))) - re) * 2.0)) * 0.5;
    	} else if (re <= 5.7e-70) {
    		tmp = Math.sqrt(((im - re) * 2.0)) * 0.5;
    	} else {
    		tmp = Math.sqrt((1.0 / re)) * (im * 0.5);
    	}
    	return tmp;
    }
    
    def code(re, im):
    	tmp = 0
    	if re <= -2.7e+145:
    		tmp = math.sqrt((-4.0 * re)) * 0.5
    	elif re <= -3e-151:
    		tmp = math.sqrt(((math.sqrt(((im * im) + (re * re))) - re) * 2.0)) * 0.5
    	elif re <= 5.7e-70:
    		tmp = math.sqrt(((im - re) * 2.0)) * 0.5
    	else:
    		tmp = math.sqrt((1.0 / re)) * (im * 0.5)
    	return tmp
    
    function code(re, im)
    	tmp = 0.0
    	if (re <= -2.7e+145)
    		tmp = Float64(sqrt(Float64(-4.0 * re)) * 0.5);
    	elseif (re <= -3e-151)
    		tmp = Float64(sqrt(Float64(Float64(sqrt(Float64(Float64(im * im) + Float64(re * re))) - re) * 2.0)) * 0.5);
    	elseif (re <= 5.7e-70)
    		tmp = Float64(sqrt(Float64(Float64(im - re) * 2.0)) * 0.5);
    	else
    		tmp = Float64(sqrt(Float64(1.0 / re)) * Float64(im * 0.5));
    	end
    	return tmp
    end
    
    function tmp_2 = code(re, im)
    	tmp = 0.0;
    	if (re <= -2.7e+145)
    		tmp = sqrt((-4.0 * re)) * 0.5;
    	elseif (re <= -3e-151)
    		tmp = sqrt(((sqrt(((im * im) + (re * re))) - re) * 2.0)) * 0.5;
    	elseif (re <= 5.7e-70)
    		tmp = sqrt(((im - re) * 2.0)) * 0.5;
    	else
    		tmp = sqrt((1.0 / re)) * (im * 0.5);
    	end
    	tmp_2 = tmp;
    end
    
    code[re_, im_] := If[LessEqual[re, -2.7e+145], N[(N[Sqrt[N[(-4.0 * re), $MachinePrecision]], $MachinePrecision] * 0.5), $MachinePrecision], If[LessEqual[re, -3e-151], N[(N[Sqrt[N[(N[(N[Sqrt[N[(N[(im * im), $MachinePrecision] + N[(re * re), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] - re), $MachinePrecision] * 2.0), $MachinePrecision]], $MachinePrecision] * 0.5), $MachinePrecision], If[LessEqual[re, 5.7e-70], N[(N[Sqrt[N[(N[(im - re), $MachinePrecision] * 2.0), $MachinePrecision]], $MachinePrecision] * 0.5), $MachinePrecision], N[(N[Sqrt[N[(1.0 / re), $MachinePrecision]], $MachinePrecision] * N[(im * 0.5), $MachinePrecision]), $MachinePrecision]]]]
    
    \begin{array}{l}
    
    \\
    \begin{array}{l}
    \mathbf{if}\;re \leq -2.7 \cdot 10^{+145}:\\
    \;\;\;\;\sqrt{-4 \cdot re} \cdot 0.5\\
    
    \mathbf{elif}\;re \leq -3 \cdot 10^{-151}:\\
    \;\;\;\;\sqrt{\left(\sqrt{im \cdot im + re \cdot re} - re\right) \cdot 2} \cdot 0.5\\
    
    \mathbf{elif}\;re \leq 5.7 \cdot 10^{-70}:\\
    \;\;\;\;\sqrt{\left(im - re\right) \cdot 2} \cdot 0.5\\
    
    \mathbf{else}:\\
    \;\;\;\;\sqrt{\frac{1}{re}} \cdot \left(im \cdot 0.5\right)\\
    
    
    \end{array}
    \end{array}
    
    Derivation
    1. Split input into 4 regimes
    2. if re < -2.70000000000000022e145

      1. Initial program 7.3%

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

        \[\leadsto \frac{1}{2} \cdot \sqrt{\color{blue}{-4 \cdot re}} \]
      4. Step-by-step derivation
        1. lower-*.f6486.7

          \[\leadsto 0.5 \cdot \sqrt{\color{blue}{-4 \cdot re}} \]
      5. Applied rewrites86.7%

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

      if -2.70000000000000022e145 < re < -3e-151

      1. Initial program 76.3%

        \[0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)} \]
      2. Add Preprocessing

      if -3e-151 < re < 5.70000000000000028e-70

      1. Initial program 53.2%

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

        \[\leadsto \frac{1}{2} \cdot \sqrt{2 \cdot \color{blue}{\left(im + -1 \cdot re\right)}} \]
      4. Step-by-step derivation
        1. mul-1-negN/A

          \[\leadsto \frac{1}{2} \cdot \sqrt{2 \cdot \left(im + \color{blue}{\left(\mathsf{neg}\left(re\right)\right)}\right)} \]
        2. unsub-negN/A

          \[\leadsto \frac{1}{2} \cdot \sqrt{2 \cdot \color{blue}{\left(im - re\right)}} \]
        3. lower--.f6484.2

          \[\leadsto 0.5 \cdot \sqrt{2 \cdot \color{blue}{\left(im - re\right)}} \]
      5. Applied rewrites84.2%

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

      if 5.70000000000000028e-70 < re

      1. Initial program 15.7%

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

        \[\leadsto \color{blue}{\frac{1}{2} \cdot \left(\left(im \cdot \left(\sqrt{\frac{1}{2}} \cdot \sqrt{2}\right)\right) \cdot \sqrt{\frac{1}{re}}\right)} \]
      4. Step-by-step derivation
        1. associate-*r*N/A

          \[\leadsto \color{blue}{\left(\frac{1}{2} \cdot \left(im \cdot \left(\sqrt{\frac{1}{2}} \cdot \sqrt{2}\right)\right)\right) \cdot \sqrt{\frac{1}{re}}} \]
        2. lower-*.f64N/A

          \[\leadsto \color{blue}{\left(\frac{1}{2} \cdot \left(im \cdot \left(\sqrt{\frac{1}{2}} \cdot \sqrt{2}\right)\right)\right) \cdot \sqrt{\frac{1}{re}}} \]
        3. associate-*r*N/A

          \[\leadsto \left(\frac{1}{2} \cdot \color{blue}{\left(\left(im \cdot \sqrt{\frac{1}{2}}\right) \cdot \sqrt{2}\right)}\right) \cdot \sqrt{\frac{1}{re}} \]
        4. associate-*r*N/A

          \[\leadsto \color{blue}{\left(\left(\frac{1}{2} \cdot \left(im \cdot \sqrt{\frac{1}{2}}\right)\right) \cdot \sqrt{2}\right)} \cdot \sqrt{\frac{1}{re}} \]
        5. lower-*.f64N/A

          \[\leadsto \color{blue}{\left(\left(\frac{1}{2} \cdot \left(im \cdot \sqrt{\frac{1}{2}}\right)\right) \cdot \sqrt{2}\right)} \cdot \sqrt{\frac{1}{re}} \]
        6. lower-*.f64N/A

          \[\leadsto \left(\color{blue}{\left(\frac{1}{2} \cdot \left(im \cdot \sqrt{\frac{1}{2}}\right)\right)} \cdot \sqrt{2}\right) \cdot \sqrt{\frac{1}{re}} \]
        7. lower-*.f64N/A

          \[\leadsto \left(\left(\frac{1}{2} \cdot \color{blue}{\left(im \cdot \sqrt{\frac{1}{2}}\right)}\right) \cdot \sqrt{2}\right) \cdot \sqrt{\frac{1}{re}} \]
        8. lower-sqrt.f64N/A

          \[\leadsto \left(\left(\frac{1}{2} \cdot \left(im \cdot \color{blue}{\sqrt{\frac{1}{2}}}\right)\right) \cdot \sqrt{2}\right) \cdot \sqrt{\frac{1}{re}} \]
        9. lower-sqrt.f64N/A

          \[\leadsto \left(\left(\frac{1}{2} \cdot \left(im \cdot \sqrt{\frac{1}{2}}\right)\right) \cdot \color{blue}{\sqrt{2}}\right) \cdot \sqrt{\frac{1}{re}} \]
        10. lower-sqrt.f64N/A

          \[\leadsto \left(\left(\frac{1}{2} \cdot \left(im \cdot \sqrt{\frac{1}{2}}\right)\right) \cdot \sqrt{2}\right) \cdot \color{blue}{\sqrt{\frac{1}{re}}} \]
        11. lower-/.f6470.2

          \[\leadsto \left(\left(0.5 \cdot \left(im \cdot \sqrt{0.5}\right)\right) \cdot \sqrt{2}\right) \cdot \sqrt{\color{blue}{\frac{1}{re}}} \]
      5. Applied rewrites70.2%

        \[\leadsto \color{blue}{\left(\left(0.5 \cdot \left(im \cdot \sqrt{0.5}\right)\right) \cdot \sqrt{2}\right) \cdot \sqrt{\frac{1}{re}}} \]
      6. Step-by-step derivation
        1. Applied rewrites70.7%

          \[\leadsto \left(im \cdot 0.5\right) \cdot \sqrt{\color{blue}{\frac{1}{re}}} \]
      7. Recombined 4 regimes into one program.
      8. Final simplification78.5%

        \[\leadsto \begin{array}{l} \mathbf{if}\;re \leq -2.7 \cdot 10^{+145}:\\ \;\;\;\;\sqrt{-4 \cdot re} \cdot 0.5\\ \mathbf{elif}\;re \leq -3 \cdot 10^{-151}:\\ \;\;\;\;\sqrt{\left(\sqrt{im \cdot im + re \cdot re} - re\right) \cdot 2} \cdot 0.5\\ \mathbf{elif}\;re \leq 5.7 \cdot 10^{-70}:\\ \;\;\;\;\sqrt{\left(im - re\right) \cdot 2} \cdot 0.5\\ \mathbf{else}:\\ \;\;\;\;\sqrt{\frac{1}{re}} \cdot \left(im \cdot 0.5\right)\\ \end{array} \]
      9. Add Preprocessing

      Reproduce

      ?
      herbie shell --seed 2024234 
      (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)))))