date and time created 83/01/21 11:21:04 by dlw

[unix-history] / usr / src / usr.bin / f77 / libF77 / z_sqrt.c

/*
*      "@(#)z_sqrt.c   1.1"
*/

#include "complex"

z_sqrt(r, z)
dcomplex *r, *z;
{
double mag, sqrt(), cabs();

if( (mag = cabs(z->dreal, z->dimag)) == 0.)
       r->dreal = r->dimag = 0.;
else if(z->dreal > 0)
       {
       r->dreal = sqrt(0.5 * (mag + z->dreal) );
       r->dimag = z->dimag / r->dreal / 2;
       }
else
       {
       r->dimag = sqrt(0.5 * (mag - z->dreal) );
       if(z->dimag < 0)
               r->dimag = - r->dimag;
       r->dreal = z->dimag / r->dimag / 2;
       }
}