tanh, tanhf, tanhl - compute hyperbolic tangent

Syntax	#include <math.h> double tanh(double x); C11 float tanhf(float x); long double tanhl(long double x); (End)
Description	These functions compute the hyperbolic tangent of a floating-point number x (within the permissible range of floating-point numbers).
Return val.	tanh(x)              Hyperbolic tangent of x if successful.
See also	atan(), cos(), cosh(), sin(), sinh(), tan(), math.h.