def dbmw_to_dbw(dbmw):
    """
    Convert dBmW to dBW.

    Given the power in the decibel milli-watts-scale, this function will evaluate
    the power in the decibel scale.

    Parameters
    ----------
    dbmw:       float
                Power in the decibel-milli-watts scale (dBmW)
    Return
    ------
    dbw:        float
                Power in the decibel scale (dBW)
    """
    return dbmw - 30