4.3BSD - /usr/src/usr.lib/libF77/z_sqrt.c

   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: }

Defined functions