code: def grid_from_coordinate_transform(numPix, Mpix2coord, ra_at_xy_0, dec_at_xy_0):
      
      a = np.arange(numPix)
      matrix = np.dstack(np.meshgrid(a, a)).reshape(-1, 2)
      x_grid = matrix[:, 0]
      y_grid = matrix[:, 1]
      ra_grid = x_grid * Mpix2coord[0, 0] + y_grid * Mpix2coord[0, 1] + ra_at_xy_0
      dec_grid = x_grid * Mpix2coord[1, 0] + y_grid * Mpix2coord[1, 1] + dec_at_xy_0
      return ra_grid, dec_grid
docs: return a grid in x and y coordinates that satisfy the coordinate system
  
  
      :param numPix:
      :param Mpix2coord:
      :param ra_at_xy_0:
      :param dec_at_xy_0:
      :return: