Average Error: 31.2 → 17.0
Time: 2.5s
Precision: binary64
\[\sqrt{re \cdot re + im \cdot im}\]
↓
\[\begin{array}{l} \mathbf{if}\;re \leq -6.47123416696789 \cdot 10^{+153}:\\ \;\;\;\;-re\\ \mathbf{elif}\;re \leq 4.916291951209594 \cdot 10^{+85}:\\ \;\;\;\;\sqrt{re \cdot re + im \cdot im}\\ \mathbf{else}:\\ \;\;\;\;re\\ \end{array}\]
\sqrt{re \cdot re + im \cdot im}
↓
\begin{array}{l}
\mathbf{if}\;re \leq -6.47123416696789 \cdot 10^{+153}:\\
\;\;\;\;-re\\

\mathbf{elif}\;re \leq 4.916291951209594 \cdot 10^{+85}:\\
\;\;\;\;\sqrt{re \cdot re + im \cdot im}\\

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

\end{array}
(FPCore (re im) :precision binary64 (sqrt (+ (* re re) (* im im))))
↓
(FPCore (re im)
 :precision binary64
 (if (<= re -6.47123416696789e+153)
   (- re)
   (if (<= re 4.916291951209594e+85) (sqrt (+ (* re re) (* im im))) re)))
double code(double re, double im) {
	return sqrt((re * re) + (im * im));
}
↓
double code(double re, double im) {
	double tmp;
	if (re <= -6.47123416696789e+153) {
		tmp = -re;
	} else if (re <= 4.916291951209594e+85) {
		tmp = sqrt((re * re) + (im * im));
	} else {
		tmp = re;
	}
	return tmp;
}

Error

Bits error versus re

Bits error versus im

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Derivation

  1. Split input into 3 regimes

  2. if re < -6.4712341669678899e153

    1. Initial program 64.0

      \[\sqrt{re \cdot re + im \cdot im}\]

    2. Taylor expanded around -inf 8.0

      \[\leadsto \color{blue}{-1 \cdot re}\]

    3. Simplified8.0

      \[\leadsto \color{blue}{-re}\]

    if -6.4712341669678899e153 < re < 4.9162919512095938e85

    1. Initial program 20.3

      \[\sqrt{re \cdot re + im \cdot im}\]

    if 4.9162919512095938e85 < re

    1. Initial program 49.7

      \[\sqrt{re \cdot re + im \cdot im}\]

    2. Taylor expanded around inf 10.8

      \[\leadsto \color{blue}{re}\]
  3. Recombined 3 regimes into one program.

  4. Final simplification17.0

    \[\leadsto \begin{array}{l} \mathbf{if}\;re \leq -6.47123416696789 \cdot 10^{+153}:\\ \;\;\;\;-re\\ \mathbf{elif}\;re \leq 4.916291951209594 \cdot 10^{+85}:\\ \;\;\;\;\sqrt{re \cdot re + im \cdot im}\\ \mathbf{else}:\\ \;\;\;\;re\\ \end{array}\]

Reproduce

herbie shell --seed 2020232 
(FPCore (re im)
  :name "math.abs on complex"
  :precision binary64
  (sqrt (+ (* re re) (* im im))))