void compute_C2()
{
struct individual *focal, *neighbour;
double distance;
double x1,x2,y1,y2;
int dx,dy;
double bin;
int bin_no;
int spp1, spp2;
int i,j, p,q, x,y,k;
double norm;
double C2[spp_no][spp_no][2*bin_max-1][2*bin_max-1];
int num=0;
double area, area1;
			for(i=0;i<spp_no;i++)
			for(j=0;j<spp_no;j++)
			for(x=0;x<2*bin_max-1;x++)
			for(y=0;y<2*bin_max-1;y++)
				{
				C2[i][j][x][y]=0.0;
				}

	focal = start;
/*
if(graphic_output==1){
color(0);
clear();
backbuffer();
}
*/
	do
		{
		num++;
		neighbour = start;

/*		if(focal->species!=environment)*/
if(graphic_output==1)
			spot(focal->xpos*4.0, focal->ypos*4.0, focal->species);

			{
			x1 = focal->xpos;
			y1 = focal->ypos;

			spp1 = focal->species;

			for(;;)
				{
					x2 = neighbour->xpos;
					y2 = neighbour->ypos;
					spp2 = neighbour->species;

				/***Compute smallest distance to neighbour inc. periodic boundaries***/
					distance = get_distance(x1,y1, x2,y2, (double)bin_max*binwidth);
					
					bin = distance/binwidth;
					bin_no = (int)bin;

					bin = x1 - x2;
					bin = bin - 0.5 * binwidth;
					bin = bin/(binwidth);
					bin = ceil(bin);
					x = (int)bin;

					bin = y1 - y2;
					bin = bin - 0.5 * binwidth;
					bin = bin/(binwidth);
					bin = ceil(bin);
					y = (int)bin;

					x = x + bin_max-1;
					y = y + bin_max-1;

				/***If distance within the maximum radius of the second moment increment C2 bin***/
					if(x>=0 && y>=0 && x<2*bin_max-1 && y<2*bin_max-1)
					if(neighbour!= focal)
						{
/*						if(x==bin_max-1)
						printf("x1: %lf\tx2: %lf\tx: %d\n", x1,x2,x);*/

						C2[spp1][spp2][x][y]+=1.0;
						}
				if(neighbour->next == NULL)
					break;
				else
					neighbour = neighbour->next;
				}
			}
			focal = focal->next;
		}while(focal!=NULL);

/*if(graphic_output==1)
swapbuffers();
*/		
		for(i=0; i<2*bin_max-1; i++)
		for(j=0; j<2*bin_max-1; j++)
			{
			if(i==bin_max-1 && j>=bin_max-1)
				{
				fprintf(C2_file, "\n%lf\t%d\t%d\t", elapsed, i-bin_max+1, j-bin_max+1);
				}

			for(spp1=0; spp1<spp_no; spp1++)
			for(spp2=0; spp2<spp_no; spp2++)
				{
			/***Compute the area at radial distance j***/
				norm = binwidth*binwidth;

			/***Now get the density of organisms at this distance***/
				C2[spp1][spp2][i][j] = C2[spp1][spp2][i][j]/norm;

			/***Now divide by the expected (given meanfield assumptions)***/
				norm = (double) (population_size[spp1] * population_size[spp2]);

				C2[spp1][spp2][i][j] = C2[spp1][spp2][i][j]/norm;

				if(i==bin_max-1 && j>=bin_max-1)
					{
				
					fprintf(C2_file, "%lf\t", C2[spp1][spp2][i][j]);
					fflush(C2_file);
					}
				}
/*			fprintf(C2_file, "\n");			*/
			}
		fprintf(C2_file, "\n\n");			

		printf("GETSHERE\n");
}