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Annotation of 42BSD/usr.lib/libF77/z_sqrt.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  *     "@(#)z_sqrt.c   1.1"
                      3:  */
                      4: 
                      5: #include "complex"
                      6: 
                      7: z_sqrt(r, z)
                      8: dcomplex *r, *z;
                      9: {
                     10: double mag, sqrt(), cabs();
                     11: 
                     12: if( (mag = cabs(z->dreal, z->dimag)) == 0.)
                     13:        r->dreal = r->dimag = 0.;
                     14: else if(z->dreal > 0)
                     15:        {
                     16:        r->dreal = sqrt(0.5 * (mag + z->dreal) );
                     17:        r->dimag = z->dimag / r->dreal / 2;
                     18:        }
                     19: else
                     20:        {
                     21:        r->dimag = sqrt(0.5 * (mag - z->dreal) );
                     22:        if(z->dimag < 0)
                     23:                r->dimag = - r->dimag;
                     24:        r->dreal = z->dimag / r->dimag / 2;
                     25:        }
                     26: }

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