libF77/z_div.c

   1 /*      $Id: z_div.c,v 1.3 2008/02/28 16:48:50 ragge Exp $      */
   2 /*
   3  * Copyright(C) Caldera International Inc. 2001-2002. All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * Redistributions of source code and documentation must retain the above
  10  * copyright notice, this list of conditions and the following disclaimer.
  11  * Redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditionsand the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution.
  14  * All advertising materials mentioning features or use of this software
  15  * must display the following acknowledgement:
  16  *      This product includes software developed or owned by Caldera
  17  *      International, Inc.
  18  * Neither the name of Caldera International, Inc. nor the names of other
  19  * contributors may be used to endorse or promote products derived from
  20  * this software without specific prior written permission.
  21  *
  22  * USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
  23  * INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
  24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  25  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  26  * DISCLAIMED.  IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OFLIABILITY, WHETHER IN CONTRACT,
  31  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  32  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  33  * POSSIBILITY OF SUCH DAMAGE.
  34  */
  35 #include <stdlib.h>
  36
  37 #include "f77lib.h"
  38
  39 void
  40 z_div(dcomplex *c, dcomplex *a, dcomplex *b)
  41 {
  42 double ratio, den;
  43 double abr, abi;
  44
  45 if( (abr = b->dreal) < 0.)
  46         abr = - abr;
  47 if( (abi = b->dimag) < 0.)
  48         abi = - abi;
  49 if( abr <= abi )
  50         {
  51         if(abi == 0)
  52                 abort(); /* fatal("complex division by zero"); */
  53         ratio = b->dreal / b->dimag ;
  54         den = b->dimag * (1 + ratio*ratio);
  55         c->dreal = (a->dreal*ratio + a->dimag) / den;
  56         c->dimag = (a->dimag*ratio - a->dreal) / den;
  57         }
  58
  59 else
  60         {
  61         ratio = b->dimag / b->dreal ;
  62         den = b->dreal * (1 + ratio*ratio);
  63         c->dreal = (a->dreal + a->dimag*ratio) / den;
  64         c->dimag = (a->dimag - a->dreal*ratio) / den;
  65         }
  66
  67 }