float coshf(float x);
coshf calculates the hyperbolic sine of x.
If |x| > ~88.7228, errno is set to EDOM and coshf returns HUGE_VALF.
If x is +∞, −∞, or NaN, coshf returns |x|.
If |x| > ~88.7228, coshf returns +∞ or −∞ depending upon the sign of x.