anchor.diff:      end do
     end do
   
  +  call wrap_fields_3D(b, nx, ny, layers)
  +
  +
     return
   end subroutine evaluate_b_iso
   
  
positive.code:       end do
      end do
    end do
  
    return
  end subroutine evaluate_zeta
  
negative.code:     end do
    end do
  
    call wrap_fields_3D(b, nx, ny, layers)
  
    return
  end subroutine evaluate_b_RedGrav
  
  