[petsc-users] Accessing array indices in 3D

[khalid ashraf]

Hi, I am writing the following loop for accessing the vectors in a 3D grid.

 for (k=zs; k<zs+zm; k++) {
  for (j=ys; j<ys+ym; j++) {
  for (i=xs; i<xs+xm; i++) {
    if (i<(mx-1))
    {
    Cx=u_localptr[k][j][i+1]-u_localptr[k][j][i];
    }
else
    {
    Cx=u_localptr[k][j][i]-u_localptr[k][j][i-1];
    }
    if (j<(my-1))
    {
//    Cy=v_localptr[k][j+1][i]-v_localptr[k][j][i];
    Cy=v_localptr[k][j][i]-v_localptr[k][j][i];
    }
else
    {
    Cy=v_localptr[k][j][i]-v_localptr[k][j-1][i];
    }
    if (k<(mz-1))
    {
//    Cz=w_localptr[k+1][j][i]-w_localptr[k][j][i];
    Cz=w_localptr[k][j][i]-w_localptr[k][j][i];
    }
else
    {
    Cz=w_localptr[k][j][i]-w_localptr[k-1][j][i];
    }
      In this code if I uncomment the two commented lines, then the program 
gives memory access out of range error when run on multiple processors. Could 
you please tell me what is the problem with the two commented out lines. 

Thanks.

Khalid


      
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