int factorial(int N) {

  int f=1,i;
  
  for (i=2;i<=N;i++)
    f*=i;
  
  return f;

}

double sum_array(double arr[], int size_array) {
  
  int n;
  double sum=0.0;
  
  for (n=0;n<size_array;n++) 
    sum+=arr[n];

  return sum;

}

