update for tahoe

[unix-history] / usr / src / usr.bin / f77 / libF77 / pow_ci.c

/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved.  The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*
*      @(#)pow_ci.c    5.2     %G%
*/

#include "complex"

#ifndef tahoe
pow_ci(p, a, b)         /* p = a**b  */
complex *p, *a;
long int *b;
{
dcomplex p1, a1;

a1.dreal = a->real;
a1.dimag = a->imag;

pow_zi(&p1, &a1, b);

p->real = p1.dreal;
p->imag = p1.dimag;
}

#else tahoe

pow_ci(p, a, b)         /* p = a**b  */
complex *p, *a;
long int *b;
{
register long int n;
register float t;
complex x;

n = *b;
p->real = 1;
p->imag = 0;

if(n == 0)
       return;
if(n < 0)
       {
       n = -n;
       c_div(&x,p,a);
       }
else
       {
       x.real = a->real;
       x.imag = a->imag;
       }

for( ; ; )
       {
       if(n & 01)
               {
               t = p->real * x.real - p->imag * x.imag;
               p->imag = p->real * x.imag + p->imag * x.real;
               p->real = t;
               }
       if(n >>= 1)
               {
               t = x.real * x.real - x.imag * x.imag;
               x.imag = 2 * x.real * x.imag;
               x.real = t;
               }
       else
               break;
       }
}
#endif tahoe