#include <cassert>

// PRE:  e >= 0 || b != 0.0 
// POST: return value is b^e
double pow (double b, int e) 
{
  assert (e >= 0 || b != 0.0);
  double result = 1.0;
  if (e < 0) {
    // b^e = (1/b)^(-e)
    b = 1.0/b;
    e = -e;
  }
  for (int i=0; i<e; ++i) result *= b;
  return result;
}