def METHOD_NAME(self, row: Axis, col: Axis, frequency: float, coords: Coords) -> complex:
    """Single component of the complex-valued permittivity tensor as a function of frequency.
    Parameters
    ----------
    row : int
        Component's row in the permittivity tensor (0, 1, or 2 for x, y, or z respectively).
    col : int
        Component's column in the permittivity tensor (0, 1, or 2 for x, y, or z respectively).
    frequency : float
        Frequency to evaluate permittivity at (Hz).
    Returns
    -------
    complex
       Element of the relative permittivity tensor evaluated at ``frequency``.
    """
    if isinstance(self.medium, AbstractCustomMedium):
        return self.medium.eps_comp_on_grid(
            row=row, col=col, frequency=frequency, coords=coords
        )
    return self.medium.METHOD_NAME(row=row, col=col, frequency=frequency)