sandbox/bugs/QuadtreeLevelZeroGhostcells.c

    Inconsistent 5x5 stencil on root level of trees

    #define BGHOSTS 2
    
    int main() {
      init_grid(2);
    
      scalar A[];
      foreach_level(0)
        A[] = 1.;
    
      foreach_dimension() {
        A[left] = neumann (0);
        A[right] = neumann (0);
      }
      boundary_level({A}, 0);
    
      foreach_level(0)
        foreach_neighbor()
          fprintf (stderr, "%g %g %g\n", x, y, A[]);
    }

    There are NaNs in some locations.

    set size ratio -1
    plot 'log' u 1:2:3 w labels
    (script)

    (script)