text: #include "complex"
  
  pow_zi(p, a, b) 	/* p = a**b  */
  dcomplex *p, *a;
  long int *b;
  {
  long int n;
  double t;
  dcomplex x;
  
  n = *b;
  p->dreal = 1;
  p->dimag = 0;
  
  if(n == 0)
  	return;
  if(n < 0)
  	{
  	n = -n;
  	z_div(&x, a);
  	}
  else
  	{
  	x.dreal = a->dreal;
  	x.dimag = a->dimag;
  	}
  
  for( ; ; )
  	{
  	if(n & 01)
  		{
  		t = p->dreal * x.dreal - p->dimag * x.dimag;
  		p->dimag = p->dreal * x.dimag + p->dimag * x.dreal;
  		p->dreal = t;
  		}
  	if(n >>= 1)
  		{
  		t = x.dreal * x.dreal - x.dimag * x.dimag;
  		x.dimag = 2 * x.dreal * x.dimag;
  		x.dreal = t;
  		}
  	else
  		break;
  	}
  }
  