0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)}\begin{array}{l}
\mathbf{if}\;re \le -1.491740461538726219683531543082814061521 \cdot 10^{111}:\\
\;\;\;\;0.5 \cdot \sqrt{2 \cdot \left(-2 \cdot re\right)}\\
\mathbf{elif}\;re \le -3.528167954050153861894555232350182828574 \cdot 10^{-301}:\\
\;\;\;\;0.5 \cdot \sqrt{2 \cdot \left(\sqrt{\sqrt{\sqrt[3]{re \cdot re + im \cdot im} \cdot \sqrt[3]{re \cdot re + im \cdot im}}} \cdot \left(\sqrt{\sqrt{\sqrt[3]{re \cdot re + im \cdot im}}} \cdot \sqrt{\sqrt{re \cdot re + im \cdot im}}\right) - re\right)}\\
\mathbf{else}:\\
\;\;\;\;0.5 \cdot \sqrt{2 \cdot \frac{{im}^{2}}{\sqrt{re \cdot re + im \cdot im} + re}}\\
\end{array}double f(double re, double im) {
double r23411 = 0.5;
double r23412 = 2.0;
double r23413 = re;
double r23414 = r23413 * r23413;
double r23415 = im;
double r23416 = r23415 * r23415;
double r23417 = r23414 + r23416;
double r23418 = sqrt(r23417);
double r23419 = r23418 - r23413;
double r23420 = r23412 * r23419;
double r23421 = sqrt(r23420);
double r23422 = r23411 * r23421;
return r23422;
}
double f(double re, double im) {
double r23423 = re;
double r23424 = -1.4917404615387262e+111;
bool r23425 = r23423 <= r23424;
double r23426 = 0.5;
double r23427 = 2.0;
double r23428 = -2.0;
double r23429 = r23428 * r23423;
double r23430 = r23427 * r23429;
double r23431 = sqrt(r23430);
double r23432 = r23426 * r23431;
double r23433 = -3.528167954050154e-301;
bool r23434 = r23423 <= r23433;
double r23435 = r23423 * r23423;
double r23436 = im;
double r23437 = r23436 * r23436;
double r23438 = r23435 + r23437;
double r23439 = cbrt(r23438);
double r23440 = r23439 * r23439;
double r23441 = sqrt(r23440);
double r23442 = sqrt(r23441);
double r23443 = sqrt(r23439);
double r23444 = sqrt(r23443);
double r23445 = sqrt(r23438);
double r23446 = sqrt(r23445);
double r23447 = r23444 * r23446;
double r23448 = r23442 * r23447;
double r23449 = r23448 - r23423;
double r23450 = r23427 * r23449;
double r23451 = sqrt(r23450);
double r23452 = r23426 * r23451;
double r23453 = 2.0;
double r23454 = pow(r23436, r23453);
double r23455 = r23445 + r23423;
double r23456 = r23454 / r23455;
double r23457 = r23427 * r23456;
double r23458 = sqrt(r23457);
double r23459 = r23426 * r23458;
double r23460 = r23434 ? r23452 : r23459;
double r23461 = r23425 ? r23432 : r23460;
return r23461;
}



Bits error versus re



Bits error versus im
Results
if re < -1.4917404615387262e+111Initial program 53.9
Taylor expanded around -inf 9.8
if -1.4917404615387262e+111 < re < -3.528167954050154e-301Initial program 20.7
rmApplied add-sqr-sqrt20.7
Applied sqrt-prod20.8
rmApplied add-cube-cbrt20.8
Applied sqrt-prod20.8
Applied sqrt-prod20.9
Applied associate-*l*20.8
if -3.528167954050154e-301 < re Initial program 46.0
rmApplied flip--45.9
Simplified36.0
Final simplification26.8
herbie shell --seed 2019308
(FPCore (re im)
:name "math.sqrt on complex, imaginary part, im greater than 0 branch"
:precision binary64
(* 0.5 (sqrt (* 2 (- (sqrt (+ (* re re) (* im im))) re)))))