#include <stdio.h>
#include "fields.h"

main(int argc, char **argv)
{
  int n, i, j;
  double *values;
  double avg;
  double variance;
  IS is;
  
  /*  First you need to get <b>n</b> from the command line arguments. */
  
  if (argc != 2) {
    fprintf(stderr, "usage: variance2 n\n");
    exit(1);
  }
  n = atoi(argv[1]);
  if (n <= 0) exit(1);

  /*  Next, you need to <b>malloc()</b> space for <b>n</b> doubles.   */

  values = (double *) malloc(sizeof(double)*n);

  /*  Next, you read them in using the fields library */

  is = new_inputstruct(NULL);
  i = 0;
  while (i < n && get_line(is) >= 0) {
    if (is->text1[0] != '#') {
      for (j = 0; j < is->NF; j++) {
        if (i < n) {
          if (sscanf(is->fields[j], "%lf", &(values[i])) != 1) exit(1);
          i++;
        }
      }
    }
  }
  if (i < n) exit(1);
  
  /*  Next, you compute their average. */

  avg = 0;
  for (i = 0; i < n; i++) {
    avg += values[i];
  }
  avg /= n;

  /*  Now, you compute the sum of the squares of the differences. */

  variance = 0;
  for (i = 0; i < n; i++) {
    variance += ((values[i]-avg)*(values[i]-avg));
  }

  /*  Finally, you compute the variance and print them both out. */

  variance /= n;

  printf("Average:  %lf\n", avg);
  printf("Variance: %lf\n", variance);
}