xref: /csrg-svn/usr.bin/f77/libF77/z_div.c (revision 10550)
1*10550Sdlw /*
2*10550Sdlw  *	"@(#)z_div.c	1.1"
3*10550Sdlw  */
4*10550Sdlw 
5*10550Sdlw #include "complex"
6*10550Sdlw 
7*10550Sdlw z_div(c, a, b)
8*10550Sdlw dcomplex *a, *b, *c;
9*10550Sdlw {
10*10550Sdlw double ratio, den;
11*10550Sdlw double abr, abi;
12*10550Sdlw 
13*10550Sdlw if( (abr = b->dreal) < 0.)
14*10550Sdlw 	abr = - abr;
15*10550Sdlw if( (abi = b->dimag) < 0.)
16*10550Sdlw 	abi = - abi;
17*10550Sdlw if( abr <= abi )
18*10550Sdlw 	{
19*10550Sdlw 	if(abi == 0)
20*10550Sdlw 		abort(); /* fatal("complex division by zero"); */
21*10550Sdlw 	ratio = b->dreal / b->dimag ;
22*10550Sdlw 	den = b->dimag * (1 + ratio*ratio);
23*10550Sdlw 	c->dreal = (a->dreal*ratio + a->dimag) / den;
24*10550Sdlw 	c->dimag = (a->dimag*ratio - a->dreal) / den;
25*10550Sdlw 	}
26*10550Sdlw 
27*10550Sdlw else
28*10550Sdlw 	{
29*10550Sdlw 	ratio = b->dimag / b->dreal ;
30*10550Sdlw 	den = b->dreal * (1 + ratio*ratio);
31*10550Sdlw 	c->dreal = (a->dreal + a->dimag*ratio) / den;
32*10550Sdlw 	c->dimag = (a->dimag - a->dreal*ratio) / den;
33*10550Sdlw 	}
34*10550Sdlw 
35*10550Sdlw }
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