def complex_permittivity_to_tan_delta(real_permittivity: float,
                                      imag_permittivity: float) -> float:
    """Computes loss tangent from complex relative permittivity

    This is a simple and straightforward calculation of a material's loss
    tangent from the real and imaginary parts of its complex relative
    permittivity.

    Args:
        real_permittivity: A `float` value for te real part of the
                           complex relative permittivity.
        imag_permittivity: A `float` value for the imaginary part of the
                           complex relative permittivity.

    Returns:
        The value for the loss tangent.

    Raises:
        ZeroDivisionError: If you specify 0 Hz, i.e. DC, for the real part
                           of the permittivity.
    """

    try:
        tan_delta = imag_permittivity / real_permittivity
    except ZeroDivisionError as error:
        raise ZeroDivisionError('Real part must be > 0'). \
              with_traceback(error.__traceback__)

    return tan_delta