[unix-history] / usr / src / libF77 / 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
0c9e74ab TL	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) double arg; {
	13
	14	double sign;
	15
	16	sign = 1.;
	17	if(arg < 0.){
	18	arg = -arg;
	19	sign = -1.;
	20	}
	21
	22	if(arg > 21.){
	23	return(sign);
	24	}
	25
	26	return(sign*sinh(arg)/cosh(arg));
	27	}