/*	tanh(arg) computes the hyperbolic tangent of its floating	point argument.	sinh and cosh are called except for large arguments, which	would cause overflow improperly.*/double sinh(), cosh();doubletanh(arg)double arg;{	double sign;	sign = 1.;	if(arg < 0.){		arg = -arg;		sign = -1.;	}	if(arg > 21.)		return(sign);	return(sign*sinh(arg)/cosh(arg));}