z_div.c

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#include "f2c.h"
#ifdef __cplusplus
extern "C" {
#endif

#ifdef KR_headers
extern VOID sig_die();
VOID z_div(c, a, b) doublecomplex *a, *b, *c;
#else
extern void sig_die(const char*, int);
void z_div(doublecomplex *c, doublecomplex *a, doublecomplex *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
                        if (a->i != 0 || a->r != 0)
                                abi = 1.;
                        c->i = c->r = abi / abr;
                        return;
#else
                        sig_die("complex division by zero", 1);
#endif
                        }
                ratio = 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 = 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;
        }
#ifdef __cplusplus
}
#endif