asinh - inverse hyperbolic sine function
#include <math.h>
double asinh(double x);
The asinh() function calculates the inverse hyperbolic
sine of x; that is the value whose hyperbolic sine is x.
SVID 3, POSIX, BSD 4.3, ISO 9899
acosh(3), atanh(3), cosh(3), sinh(3), tanh(3)