[unix-history] / usr / src / libm / tanh.c

/*
	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();

double
tanh(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));
}
Commit	Line	Data
5d130d40 RM	1	/*
	2	tanh(arg) computes the hyperbolic tangent of its floating
	3	point argument.
	4
	5	sinh and cosh are called except for large arguments, which
	6	would cause overflow improperly.
	7	*/
	8
	9	double sinh(), cosh();
	10
	11	double
	12	tanh(arg)
	13	double arg;
	14	{
	15	double sign;
	16
	17	sign = 1.;
	18	if(arg < 0.){
	19	arg = -arg;
	20	sign = -1.;
	21	}
	22
	23	if(arg > 21.)
	24	return(sign);
	25
	26	return(sign*sinh(arg)/cosh(arg));
	27	}