\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 \left(2 \cdot \log \left(\sqrt[3]{\sqrt[3]{e^{\mathsf{log1p}\left(a\right)}}}\right) + \log \left(\sqrt[3]{\sqrt[3]{e^{\mathsf{log1p}\left(a\right)}}}\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 r23276 = a;
double r23277 = cosh(r23276);
double r23278 = r23276 * r23276;
double r23279 = fmod(r23277, r23278);
double r23280 = log1p(r23276);
double r23281 = pow(r23279, r23280);
double r23282 = acos(r23281);
return r23282;
}
double f(double a) {
double r23283 = a;
double r23284 = 1.542338768776222e-162;
bool r23285 = r23283 <= r23284;
double r23286 = cosh(r23283);
double r23287 = r23283 * r23283;
double r23288 = fmod(r23286, r23287);
double r23289 = 2.0;
double r23290 = log1p(r23283);
double r23291 = exp(r23290);
double r23292 = cbrt(r23291);
double r23293 = cbrt(r23292);
double r23294 = log(r23293);
double r23295 = r23289 * r23294;
double r23296 = r23295 + r23294;
double r23297 = r23289 * r23296;
double r23298 = log(r23292);
double r23299 = r23297 + r23298;
double r23300 = pow(r23288, r23299);
double r23301 = acos(r23300);
double r23302 = exp(r23288);
double r23303 = log(r23302);
double r23304 = pow(r23303, r23290);
double r23305 = acos(r23304);
double r23306 = r23285 ? r23301 : r23305;
return r23306;
}



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
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))))