c_div.c   [plain text]

#include "f2c.h"

#ifdef KR_headers
extern VOID sig_die();
VOID c_div(c, a, b)
complex *a, *b, *c;
#else
extern void sig_die(char*,int);
void c_div(complex *c, complex *a, complex *b)
#endif
{
	double ratio, den;
	double abr, abi, cr;

	if( (abr = b->r) < 0.)
		abr = - abr;
	if( (abi = b->i) < 0.)
		abi = - abi;
	if( abr <= abi )
		{
		if(abi == 0) {
#ifdef IEEE_COMPLEX_DIVIDE
			float af, bf;
			af = bf = abr;
			if (a->i != 0 || a->r != 0)
				af = 1.;
			c->i = c->r = af / bf;
			return;
#else
			sig_die("complex division by zero", 1);
#endif
			}
		ratio = (double)b->r / b->i ;
		den = b->i * (1 + ratio*ratio);
		cr = (a->r*ratio + a->i) / den;
		c->i = (a->i*ratio - a->r) / den;
		}

	else
		{
		ratio = (double)b->i / b->r ;
		den = b->r * (1 + ratio*ratio);
		cr = (a->r + a->i*ratio) / den;
		c->i = (a->i - a->r*ratio) / den;
		}
	c->r = cr;
	}