external/bsd/pcc/dist/pcc-libs/libF77/pow_zi.c

   1 /*      $Id: pow_zi.c,v 1.1.1.1 2008/08/24 05:34:46 gmcgarry 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 "f77lib.h"
  36
  37 void
  38 pow_zi(dcomplex *p, dcomplex *a, long int *b)   /* p = a**b  */
  39 {
  40         long int n;
  41         double t;
  42         dcomplex x;
  43
  44         n = *b;
  45         p->dreal = 1;
  46         p->dimag = 0;
  47
  48         if(n == 0)
  49                 return;
  50         if(n < 0) {
  51                 n = -n;
  52                 z_div(&x, p, a);
  53         } else {
  54                 x.dreal = a->dreal;
  55                 x.dimag = a->dimag;
  56         }
  57
  58         for( ; ; ) {
  59                 if(n & 01) {
  60                         t = p->dreal * x.dreal - p->dimag * x.dimag;
  61                         p->dimag = p->dreal * x.dimag + p->dimag * x.dreal;
  62                         p->dreal = t;
  63                 }
  64                 if(n >>= 1) {
  65                         t = x.dreal * x.dreal - x.dimag * x.dimag;
  66                         x.dimag = 2 * x.dreal * x.dimag;
  67                         x.dreal = t;
  68                 } else
  69                         break;
  70         }
  71 }