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; } }