/********************************************************************** * Copyright (c) Digital Equipment Corporation 1984, 1985, 1986. * * All Rights Reserved. * * Reference "/usr/src/COPYRIGHT" for applicable restrictions. * **********************************************************************/ /* * SCCSID: @(#)z_sqrt.c 3.0 4/22/86 */ #include "complex" z_sqrt(r, z) dcomplex *r, *z; { double mag, sqrt(), cabs(); if( (mag = cabs(z->dreal, z->dimag)) == 0.) r->dreal = r->dimag = 0.; else if(z->dreal > 0) { r->dreal = sqrt(0.5 * (mag + z->dreal) ); r->dimag = z->dimag / r->dreal / 2; } else { r->dimag = sqrt(0.5 * (mag - z->dreal) ); if(z->dimag < 0) z->dimag = - z->dimag; r->dreal = z->dimag / r->dimag / 2; } }