Bell 32V development

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

struct dcomplex { double dreal, dimag; };

z_div(c, a, b)
struct dcomplex *a, *b, *c;
{
double ratio, den;
double abr, abi;

if( (abr = b->dreal) < 0.)
       abr = - abr;
if( (abi = b->dimag) < 0.)
       abi = - abi;
if( abr <= abi )
       {
       if(abi == 0)
               abort(); /* fatal("complex division by zero"); */
       ratio = b->dreal / b->dimag ;
       den = b->dimag * (1 + ratio*ratio);
       c->dreal = (a->dreal*ratio + a->dimag) / den;
       c->dimag = (a->dimag*ratio - a->dreal) / den;
       }

else
       {
       ratio = b->dimag / b->dreal ;
       den = b->dreal * (1 + ratio*ratio);
       c->dreal = (a->dreal + a->dimag*ratio) / den;
       c->dimag = (a->dimag - a->dreal*ratio) / den;
       }

}