This commit was generated by cvs2svn to track changes on a CVS vendor

[unix-history] / lib / libF77 / pow_zi.c

#include "f2c.h"

#ifdef KR_headers
VOID pow_zi(p, a, b)    /* p = a**b  */
doublecomplex *p, *a; integer *b;
#else
extern void z_div(doublecomplex*, doublecomplex*, doublecomplex*);
void pow_zi(doublecomplex *p, doublecomplex *a, integer *b)     /* p = a**b  */
#endif
{
integer n;
double t;
doublecomplex x;
static doublecomplex one = {1.0, 0.0};

n = *b;
p->r = 1;
p->i = 0;

if(n == 0)
       return;
if(n < 0)
       {
       n = -n;
       z_div(&x, &one, a);
       }
else
       {
       x.r = a->r;
       x.i = a->i;
       }

for( ; ; )
       {
       if(n & 01)
               {
               t = p->r * x.r - p->i * x.i;
               p->i = p->r * x.i + p->i * x.r;
               p->r = t;
               }
       if(n >>= 1)
               {
               t = x.r * x.r - x.i * x.i;
               x.i = 2 * x.r * x.i;
               x.r = t;
               }
       else
               break;
       }
}