\cos^{-1} \left({\left(\left(\cosh a\right) \bmod \left(a \cdot a\right)\right)}^{\left(\mathsf{log1p}\left(a\right)\right)}\right)\begin{array}{l}
\mathbf{if}\;a \le 1.542338768776221979718923094404481642848 \cdot 10^{-162}:\\
\;\;\;\;\cos^{-1} \left({\left(\left(\cosh a\right) \bmod \left(a \cdot a\right)\right)}^{\left(2 \cdot \log \left(\sqrt[3]{e^{\mathsf{log1p}\left(a\right)}}\right) + \log \left(\sqrt[3]{e^{\mathsf{log1p}\left(a\right)}}\right)\right)}\right)\\
\mathbf{else}:\\
\;\;\;\;\cos^{-1} \left({\left(\log \left(e^{\left(\left(\cosh a\right) \bmod \left(a \cdot a\right)\right)}\right)\right)}^{\left(\mathsf{log1p}\left(a\right)\right)}\right)\\
\end{array}double f(double a) {
double r23446 = a;
double r23447 = cosh(r23446);
double r23448 = r23446 * r23446;
double r23449 = fmod(r23447, r23448);
double r23450 = log1p(r23446);
double r23451 = pow(r23449, r23450);
double r23452 = acos(r23451);
return r23452;
}
double f(double a) {
double r23453 = a;
double r23454 = 1.542338768776222e-162;
bool r23455 = r23453 <= r23454;
double r23456 = cosh(r23453);
double r23457 = r23453 * r23453;
double r23458 = fmod(r23456, r23457);
double r23459 = 2.0;
double r23460 = log1p(r23453);
double r23461 = exp(r23460);
double r23462 = cbrt(r23461);
double r23463 = log(r23462);
double r23464 = r23459 * r23463;
double r23465 = r23464 + r23463;
double r23466 = pow(r23458, r23465);
double r23467 = acos(r23466);
double r23468 = exp(r23458);
double r23469 = log(r23468);
double r23470 = pow(r23469, r23460);
double r23471 = acos(r23470);
double r23472 = r23455 ? r23467 : r23471;
return r23472;
}



Bits error versus a
if a < 1.542338768776222e-162Initial program 64.0
rmApplied add-log-exp61.3
rmApplied add-cube-cbrt61.3
Applied log-prod61.3
Simplified61.3
if 1.542338768776222e-162 < a Initial program 58.8
rmApplied add-log-exp56.9
Final simplification59.0
herbie shell --seed 2019325
(FPCore (a)
:name "Random Jason Timeout Test 012"
:precision binary64
(acos (pow (fmod (cosh a) (* a a)) (log1p a))))