CCTK_REAL refined_radius "size of the refined region at the center"
{
  (0:* :: "any positive size"
} 0.25
CCTK_INT regrid_after "when to change the grid"
{
  0   :: "at initial data time"
  1:* :: "after this iteration"
} 1

#include <cmath>

  CCTK_VINFO("Initializing data of size %d %d %d", cctk_lsh[0], cctk_lsh[1],
             cctk_lsh[2]);

    ptrdiff_t idx = p.idx;
    CCTK_REAL xL = p.x;
    CCTK_REAL yL = p.y;
    CCTK_REAL zL = p.z;
    data[idx] = xL;

    data[p.idx] = p.x;

  if (cctk_iteration < 1)

  if (cctk_iteration < regrid_after)

  printf("Setting grid\n");

  CCTK_VINFO("Setting grid at %d\n", cctk_iteration);

    if (p.x > -0.5 && p.x < 0.5 && p.y > -0.5 && p.y < 0.5 && p.z > -0.5 &&
        p.z < 0.5) {
      fprintf(stderr, "Setting error %g %g %g\n", p.x, p.y, p.z);

    if (fabs(p.x) <= refined_radius && fabs(p.y) <= refined_radius &&
        fabs(p.z) <= refined_radius) {

  fprintf(stderr, "done\n");

$ncells = 8

$ncells = 20

Cactus::cctk_itlast = 4

Cactus::cctk_itlast = 2

AMReX::prolongation_order = 4

AMReX::prolongation_order = 1