Synopsis
double cosh(double x);
Description

cosh calculates the hyperbolic cosine of x.

If |x| > ~709.782, errno is set to EDOM and cosh returns HUGE_VAL.

If x is +∞, −∞, or NaN, cosh returns |x|.> If |x| > ~709.782, cosh returns +∞ or −∞ depending upon the sign of x.