4.3BSD - /usr/src/usr.lib/libF77/pow_zi.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:  *	@(#)pow_zi.c	5.1	6/7/85
   7:  */
   8: 
   9: #include "complex"
  10: 
  11: pow_zi(p, a, b)     /* p = a**b  */
  12: dcomplex *p, *a;
  13: long int *b;
  14: {
  15: long int n;
  16: double t;
  17: dcomplex x;
  18: 
  19: n = *b;
  20: p->dreal = 1;
  21: p->dimag = 0;
  22: 
  23: if(n == 0)
  24:     return;
  25: if(n < 0)
  26:     {
  27:     n = -n;
  28:     z_div(&x, p, a);
  29:     }
  30: else
  31:     {
  32:     x.dreal = a->dreal;
  33:     x.dimag = a->dimag;
  34:     }
  35: 
  36: for( ; ; )
  37:     {
  38:     if(n & 01)
  39:         {
  40:         t = p->dreal * x.dreal - p->dimag * x.dimag;
  41:         p->dimag = p->dreal * x.dimag + p->dimag * x.dreal;
  42:         p->dreal = t;
  43:         }
  44:     if(n >>= 1)
  45:         {
  46:         t = x.dreal * x.dreal - x.dimag * x.dimag;
  47:         x.dimag = 2 * x.dreal * x.dimag;
  48:         x.dreal = t;
  49:         }
  50:     else
  51:         break;
  52:     }
  53: }

Defined functions