#include "geostat.h"

/*builds the sampled covariance function*/
/*dimensions are even*/
void covariance(double *covar, struct vario_mod variogram, struct grid_mod mesh, int n[3])

{
  int i,j,k,maille,n2[3],symmetric;
  double di,dj,dk;

  printf("covaridsadsncdse\n");
  

  for (i=0;i<3;i++) 
    n2[i] = n[i]/2;

  for (i=0; i<= n2[0]; i++) {
    for (j=0; j<= n2[1]; j++) {
      for (k=0; k<= n2[2]; k++) {
    

	/*area 1*/
	maille = 1+i+n[0]*(j+n[1]*k);
	di = (double)i*mesh.DX;
	dj = (double)j*mesh.DY;
	dk = (double)k*mesh.DZ;
	covar[maille] = (double)cov_value(variogram,di,dj,dk);

	
	if (k > 0 && k <n2[2] && j > 0 && j <n2[1] && i > 0 && i <n2[0]) {
	  /*area 2*/
	  symmetric = 1+n[0]-i+n[0]*(n[1]-j+n[1]*(n[2]-k));
	  covar[symmetric] = covar[maille];
	}


	if (i > 0 && i <n2[0]) {
	  /*area 4*/
	  di = -(double)i*mesh.DX;
	  dj = (double)j*mesh.DY;
	  dk = (double)k*mesh.DZ;
	  maille = 1+(n[0]-i)+n[0]*(j+n[1]*k);
	  covar[maille] = (double)cov_value(variogram,di,dj,dk);
	}


	if (k > 0 && k <n2[2] && j > 0 && j <n2[1]) {
	  /*area 8*/
	  symmetric = 1+i+n[0]*(n[1]-j+n[1]*(n[2]-k));
	  covar[symmetric] = covar[maille];
	}


	if (i > 0 && i <n2[0] && j > 0 && j < n2[1]) {
	  /*area 5*/
	  di = -(double)i*mesh.DX;
	  dj = -(double)j*mesh.DY;
	  dk = (double)k*mesh.DZ;
	  maille = 1+(n[0]-i)+n[0]*(n[1]-j+n[1]*k);
	  covar[maille] = (double)cov_value(variogram,di,dj,dk);
	}


	if (k > 0 && k <n2[2]) {
	  /*area 6*/
	  symmetric = 1+i+n[0]*(j+n[1]*(n[2]-k));
	  covar[symmetric] = covar[maille];
	}


	if (j > 0 && j < n2[1]) {
	  /*area 3*/
	  di = (double)i*mesh.DX;
	  dj = -(double)j*mesh.DY;
	  dk = (double)k*mesh.DZ;
	  maille = 1+i+n[0]*(n[1]-j+n[1]*k);
	  covar[maille] = (double)cov_value(variogram,di,dj,dk);
	}


	if (k > 0 && k <n2[2] && i > 0 && i <n2[0]) {
	  /*area 7*/
	  symmetric = 1+n[0]-i+n[0]*(j+n[1]*(n[2]-k));
	  covar[symmetric] = covar[maille];
	}

      }
    }
  }

  return;
}