/* sum of a list of doubles */
double sum(double *data, int n)
{
  int i=0;
  double sum=0.0;
 
  for (i=0; i<n; i++)
  {
  sum += data[i];
  }
  return sum;
}

/* mean of a list of doubles */
double mean(double *data, int n)
{
  double s = sum(data, n);
  return s/((double)n);
}