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

/*
*      "@(#)z_div.c    1.2"
*/

#include "complex"
#include <stdio.h>
#include <errno.h>

z_div(c, a, b)
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) {
               fprintf( stderr, "Double complex division by zero\n" );
               f77_abort(EDOM);
       }
       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;
       }

}