\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 1.5952721721417026 \cdot 10^{-162}:\\
\;\;\;\;\cos^{-1} \left({\left({\left(\log \left(e^{\left(\left(\cosh a\right) \bmod \left(a \cdot a\right)\right)}\right)\right)}^{\left(\sqrt{\mathsf{log1p}\left(a\right)}\right)}\right)}^{\left(\log \left(e^{\sqrt{\mathsf{log1p}\left(a\right)}}\right)\right)}\right)\\
\mathbf{else}:\\
\;\;\;\;\frac{\pi}{2} - \sin^{-1} \left({\left({\left(\log \left(e^{\left(\left(\cosh a\right) \bmod \left(a \cdot a\right)\right)}\right)\right)}^{\left(\sqrt{\mathsf{log1p}\left(a\right)}\right)}\right)}^{\left(\sqrt{\mathsf{log1p}\left(a\right)}\right)}\right)\\
\end{array}double code(double a) {
return acos(pow(fmod(cosh(a), (a * a)), log1p(a)));
}
double code(double a) {
double VAR;
if ((a <= 1.5952721721417026e-162)) {
VAR = acos(pow(pow(log(exp(fmod(cosh(a), (a * a)))), sqrt(log1p(a))), log(exp(sqrt(log1p(a))))));
} else {
VAR = ((((double) M_PI) / 2.0) - asin(pow(pow(log(exp(fmod(cosh(a), (a * a)))), sqrt(log1p(a))), sqrt(log1p(a)))));
}
return VAR;
}



Bits error versus a
Results
if a < 1.5952721721417026e-162Initial program 64.0
rmApplied add-log-exp64.0
rmApplied add-sqr-sqrt64.0
Applied pow-unpow64.0
rmApplied add-log-exp61.3
if 1.5952721721417026e-162 < a Initial program 58.6
rmApplied add-log-exp56.9
rmApplied add-sqr-sqrt56.9
Applied pow-unpow56.9
rmApplied acos-asin56.9
Final simplification59.0
herbie shell --seed 2020105
(FPCore (a)
:name "Random Jason Timeout Test 012"
:precision binary64
(acos (pow (fmod (cosh a) (* a a)) (log1p a))))