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Correlation on DSP KIT TMS320C6713 Simulator

● December 15, 2010 ● Coded in C++ for the TI C67x
#include <stdio.h>
#include <math.h>

double pi=3.14159;

float x[50],y[50];
float r[100];

void correlation(float *x,float *y, int nx, int ny);

int main()
{   
   

int ii;
for(ii=0;ii<50  ;ii++)
 {
	 x[ii]=sin(2.0*pi*ii*3/50);
 	 y[ii]=sin(2.0*pi*ii*3/50);

 }

correlation(x,y,50,50);

printf("Complete.\n");

return 0;
}

void correlation(float *x,float *y, int nx, int ny)
{
	int n=50,delay=0,maxdelay=50;
	int i,j;
   double mx,my,sx,sy,sxy,denom;
  
   
   /* Calculate the mean of the two series x[], y[] */
   mx = 0;
   my = 0;   
	   for (i=0;i<n;i++) 
		   {
			  mx += x[i];
			  my += y[i];
		   }
   mx /= n;
   my /= n;

   /* Calculate the denominator */
   sx = 0;
   sy = 0;
	   for (i=0;i<n;i++) 
		   {
			  sx += (x[i] - mx) * (x[i] - mx);
			  sy += (y[i] - my) * (y[i] - my);
		   }
   denom = sqrt(sx*sy);

   /* Calculate the correlation series */
   for (delay=-maxdelay;delay<maxdelay;delay++) 
	   {
		  sxy = 0;
			  for (i=0;i<n;i++) 
				  {
					 j = i + delay;
	 if (j < 0 || j >= n)
						continue;
	 else
						sxy += (x[i] - mx) * (y[j] - my);
					 // Or should it be (?)
					/* if (j < 0 || j >= n)
						sxy += (x[i] - mx) * (-my);
					 else
						sxy += (x[i] - mx) * (y[j] - my);*/
					 
				  }
r[delay+maxdelay]= ( sxy / denom);