text: def asselin( varm, var, varp, asscoef, nx, nz):
  
      # Apply Asselin filtering for 2dt filtering
      for k in range(1, nz-2):
          for i in range(1, nx-2):
  
              var[i, k] = var[i, k] + asscoef*(varp[i, k]-2*var[i, k]+varm[i, k])
  
      return varm, var, varp
  