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Annotation of 43BSD/usr.lib/libF77/z_sqrt.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1980 Regents of the University of California.
                      3:  * All rights reserved.  The Berkeley software License Agreement
                      4:  * specifies the terms and conditions for redistribution.
                      5:  *
                      6:  *     @(#)z_sqrt.c    5.1     6/7/85
                      7:  */
                      8: 
                      9: #include "complex"
                     10: 
                     11: z_sqrt(r, z)
                     12: dcomplex *r, *z;
                     13: {
                     14: double mag, sqrt(), cabs();
                     15: 
                     16: if( (mag = cabs(z->dreal, z->dimag)) == 0.)
                     17:        r->dreal = r->dimag = 0.;
                     18: else if(z->dreal > 0)
                     19:        {
                     20:        r->dreal = sqrt(0.5 * (mag + z->dreal) );
                     21:        r->dimag = z->dimag / r->dreal / 2;
                     22:        }
                     23: else
                     24:        {
                     25:        r->dimag = sqrt(0.5 * (mag - z->dreal) );
                     26:        if(z->dimag < 0)
                     27:                r->dimag = - r->dimag;
                     28:        r->dreal = z->dimag / r->dimag / 2;
                     29:        }
                     30: }

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