0.5 \cdot \sqrt{2 \cdot \left(\sqrt{re \cdot re + im \cdot im} - re\right)}\begin{array}{l}
\mathbf{if}\;re \le -1.181793183213821728908776663248811693415 \cdot 10^{151}:\\
\;\;\;\;\sqrt{\left(-2 \cdot re\right) \cdot 2} \cdot 0.5\\
\mathbf{elif}\;re \le 7.789430045443286732009817813286096796361 \cdot 10^{-277}:\\
\;\;\;\;\sqrt{2 \cdot \left(\sqrt{im \cdot im + re \cdot re} - re\right)} \cdot 0.5\\
\mathbf{else}:\\
\;\;\;\;0.5 \cdot \frac{\sqrt{2 \cdot \left(im \cdot im\right)}}{\sqrt{re + \sqrt{im \cdot im + re \cdot re}}}\\
\end{array}double f(double re, double im) {
double r28308 = 0.5;
double r28309 = 2.0;
double r28310 = re;
double r28311 = r28310 * r28310;
double r28312 = im;
double r28313 = r28312 * r28312;
double r28314 = r28311 + r28313;
double r28315 = sqrt(r28314);
double r28316 = r28315 - r28310;
double r28317 = r28309 * r28316;
double r28318 = sqrt(r28317);
double r28319 = r28308 * r28318;
return r28319;
}
double f(double re, double im) {
double r28320 = re;
double r28321 = -1.1817931832138217e+151;
bool r28322 = r28320 <= r28321;
double r28323 = -2.0;
double r28324 = r28323 * r28320;
double r28325 = 2.0;
double r28326 = r28324 * r28325;
double r28327 = sqrt(r28326);
double r28328 = 0.5;
double r28329 = r28327 * r28328;
double r28330 = 7.789430045443287e-277;
bool r28331 = r28320 <= r28330;
double r28332 = im;
double r28333 = r28332 * r28332;
double r28334 = r28320 * r28320;
double r28335 = r28333 + r28334;
double r28336 = sqrt(r28335);
double r28337 = r28336 - r28320;
double r28338 = r28325 * r28337;
double r28339 = sqrt(r28338);
double r28340 = r28339 * r28328;
double r28341 = r28325 * r28333;
double r28342 = sqrt(r28341);
double r28343 = r28320 + r28336;
double r28344 = sqrt(r28343);
double r28345 = r28342 / r28344;
double r28346 = r28328 * r28345;
double r28347 = r28331 ? r28340 : r28346;
double r28348 = r28322 ? r28329 : r28347;
return r28348;
}



Bits error versus re



Bits error versus im
Results
if re < -1.1817931832138217e+151Initial program 63.1
Taylor expanded around -inf 8.4
Simplified8.4
if -1.1817931832138217e+151 < re < 7.789430045443287e-277Initial program 21.0
rmApplied pow121.0
if 7.789430045443287e-277 < re Initial program 46.1
rmApplied pow146.1
rmApplied flip--46.0
Applied associate-*r/46.0
Applied sqrt-div46.1
Simplified35.1
Simplified35.1
Final simplification26.1
herbie shell --seed 2019174
(FPCore (re im)
:name "math.sqrt on complex, imaginary part, im greater than 0 branch"
(* 0.5 (sqrt (* 2.0 (- (sqrt (+ (* re re) (* im im))) re)))))