[unix-history] / usr / src / libF77 / c_sqrt.c

#include "complex"

c_sqrt(r, z)
complex *r, *z;
{
double mag, sqrt(), cabs();

if( (mag = cabs(z->real, z->imag)) == 0.)
	r->real = r->imag = 0.;
else if(z->real > 0)
	{
	r->real = sqrt(0.5 * (mag + z->real) );
	r->imag = z->imag / r->real / 2;
	}
else
	{
	r->imag = sqrt(0.5 * (mag - z->real) );
	if(z->imag < 0)
		r->imag = - r->imag;
	r->real = z->imag / r->imag /2;
	}
}
Commit	Line	Data
0c9e74ab TL	1	#include "complex"
	2
	3	c_sqrt(r, z)
	4	complex r, z;
	5	{
	6	double mag, sqrt(), cabs();
	7
	8	if( (mag = cabs(z->real, z->imag)) == 0.)
	9	r->real = r->imag = 0.;
	10	else if(z->real > 0)
	11	{
	12	r->real = sqrt(0.5 * (mag + z->real) );
	13	r->imag = z->imag / r->real / 2;
	14	}
	15	else
	16	{
	17	r->imag = sqrt(0.5 * (mag - z->real) );
	18	if(z->imag < 0)
	19	r->imag = - r->imag;
	20	r->real = z->imag / r->imag /2;
	21	}
	22	}