LT3_get_loc Function

  elemental function LT3_get_loc(my_lt, x1, x2, x3) result(my_loc)
    type(LT3_t), intent(in) :: my_lt
    real(dp), intent(in)    :: x1, x2, x3
    type(LT3_loc_t)         :: my_loc
    real(dp)                :: frac(3)

    frac            = ([x1, x2, x3] - my_lt%x_min) * my_lt%inv_dx
    my_loc%low_ix   = ceiling(frac)
    my_loc%low_frac = my_loc%low_ix - frac

    ! Check bounds
    where (my_loc%low_ix < 1)
       my_loc%low_ix   = 1
       my_loc%low_frac = 1
    end where

    where (my_loc%low_ix >= my_lt%n_points)
       my_loc%low_ix   = my_lt%n_points - 1
       my_loc%low_frac = 0
    end where
  end function LT3_get_loc