#include <math.h>
#define M 5
float correlate();
float sum_sqr_2();
float sum_both_2();

main()
{
  int f[100]; int g[100]; 
  int gs,ge, fs, fe, n;
  int sum, m;
  float num; 
  float g_bar, g_sqrs;

  init_corr (f,g);
  
  printf ("gs?");
  scanf ("%d", &gs);
  printf ("ge?");
  scanf ("%d", &ge);
  printf ("fs?");
  scanf ("%d", &fs);

  n = ge-gs;
  printf ("n: %d\n", n);
  
  sum   = sum_funct (g, gs, n); 
  g_bar = (float)sum / n;
  g_sqrs = sum_sqr_2 (g, gs, n, g_bar);
#ifdef ROGER
  printf ("g_bar: %f", g_bar);
  printf ("  g_sqrs: %f\n", g_sqrs);
#endif
  for (m = -M; m <= M; m++)
  {
    num = correlate (g_bar, g_sqrs, f,g, gs,ge, fs+m, n);
    printf ("=========================================\n"); 
    printf ("m: %d ----> correl_value: %f\n", m, num);
    printf ("=========================================\n"); 
  }
}

init_corr(f,g)
int f[]; int g[];
{
  int x;
  for (x=0;x<=100;x++)
  {
    if (x<8)
      f[x] = 0;
    else
      f[x] = x-8;
    if (x<4)
      g[x] = 0;
    else
      g[x] = x-4;
    /*printf ("f[%d]: %d", x, f[x]);
    printf ("  --- g[%d]: %d\n", x, g[x]); 
   */ 
  }
}

sum_funct (array, s,n)
int array[]; int s,n;
{
  int x;
  int sum = 0;
  for (x=s;x<= s+n;x++)
  {
    sum = sum + array[x];
  }
  return (sum);
}

float sum_both_2 (f,g, gs,ge, fs, f_bar, g_bar)
int f[], g[]; int gs,ge, fs;
float f_bar, g_bar;
{
  int x;
  float numer = 0.0;
  int ind;
  ind = fs; 
  for (x=gs;x<=ge;x++)
  {
    numer = numer + ( ((float)f[ind] - f_bar) * ((float)g[x] - g_bar) );
    ind++; 
  }
  return (numer);
}

float sum_sqr_2 (array, s,n, ave)
int array[]; int s,n;
float ave;
{
  int x;
  float num;
  float sum = 0.0;
  for (x=s;x<=s+n;x++)
  {
    num = (float)array[x] - ave; 
    sum = sum + (num * num);
  }
  return (sum);
}

float correlate(g_bar, g_sqrs, f,g, gs,ge, fs, n)
float g_bar, g_sqrs; int f[],g[], gs,ge, fs, n;
{
  int one, two, mt; 
  float numer, denom, first, second;
  float correl_value;
  float f_bar, f_sqrs;

  f_bar = sum_funct (f, fs, n); 
  f_bar = f_bar / n; 
#ifdef ROGER
  printf (" f_bar: %f", f_bar);
#endif  
  numer = sum_both_2 (f,g, gs,ge, fs, f_bar, g_bar);
  
  f_sqrs = sum_sqr_2 (f, fs, n, f_bar);
#ifdef ROGER
  printf ("  f_sqrs: %f\n", f_sqrs);
#endif  
  denom = sqrt ((float)f_sqrs * (float)g_sqrs); 
  correl_value = (float)numer/denom; 
#ifdef ROGER
  printf ("numer: %f  denom: %f corr: %f\n", 
           numer, denom, correl_value);
#endif  
  return (correl_value);
}