Average Error: 31.7 → 17.3
Time: 1.2s
Precision: binary64
\[\log \left(\sqrt{re \cdot re + im \cdot im}\right)\]
↓
\[\begin{array}{l} \mathbf{if}\;re \leq -6.905514095732964 \cdot 10^{+131}:\\ \;\;\;\;\log \left(-re\right)\\ \mathbf{elif}\;re \leq 3.099410482298467 \cdot 10^{+86}:\\ \;\;\;\;\log \left(\sqrt{re \cdot re + im \cdot im}\right)\\ \mathbf{else}:\\ \;\;\;\;\log re\\ \end{array}\]
\log \left(\sqrt{re \cdot re + im \cdot im}\right)
↓
\begin{array}{l}
\mathbf{if}\;re \leq -6.905514095732964 \cdot 10^{+131}:\\
\;\;\;\;\log \left(-re\right)\\

\mathbf{elif}\;re \leq 3.099410482298467 \cdot 10^{+86}:\\
\;\;\;\;\log \left(\sqrt{re \cdot re + im \cdot im}\right)\\

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

\end{array}
(FPCore (re im) :precision binary64 (log (sqrt (+ (* re re) (* im im)))))
↓
(FPCore (re im)
 :precision binary64
 (if (<= re -6.905514095732964e+131)
   (log (- re))
   (if (<= re 3.099410482298467e+86)
     (log (sqrt (+ (* re re) (* im im))))
     (log re))))
double code(double re, double im) {
	return log(sqrt((re * re) + (im * im)));
}
↓
double code(double re, double im) {
	double tmp;
	if (re <= -6.905514095732964e+131) {
		tmp = log(-re);
	} else if (re <= 3.099410482298467e+86) {
		tmp = log(sqrt((re * re) + (im * im)));
	} else {
		tmp = log(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 < -6.905514095732964e131

    1. Initial program 58.6

      \[\log \left(\sqrt{re \cdot re + im \cdot im}\right)\]

    2. Taylor expanded around -inf 7.8

      \[\leadsto \log \color{blue}{\left(-1 \cdot re\right)}\]

    3. Simplified7.8

      \[\leadsto \log \color{blue}{\left(-re\right)}\]

    if -6.905514095732964e131 < re < 3.0994104822984672e86

    1. Initial program 21.4

      \[\log \left(\sqrt{re \cdot re + im \cdot im}\right)\]

    if 3.0994104822984672e86 < re

    1. Initial program 48.8

      \[\log \left(\sqrt{re \cdot re + im \cdot im}\right)\]

    2. Taylor expanded around inf 9.4

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

  4. Final simplification17.3

    \[\leadsto \begin{array}{l} \mathbf{if}\;re \leq -6.905514095732964 \cdot 10^{+131}:\\ \;\;\;\;\log \left(-re\right)\\ \mathbf{elif}\;re \leq 3.099410482298467 \cdot 10^{+86}:\\ \;\;\;\;\log \left(\sqrt{re \cdot re + im \cdot im}\right)\\ \mathbf{else}:\\ \;\;\;\;\log re\\ \end{array}\]

Reproduce

herbie shell --seed 2020253 
(FPCore (re im)
  :name "math.log/1 on complex, real part"
  :precision binary64
  (log (sqrt (+ (* re re) (* im im)))))