import math


def add_smooth_sigma_round(cli_args, cur_smooth):
    """
    Pull user-defined smoothing variables, calculate the sigma value for
    additional smoothing, and round the sigma value to 7 decimal places
    :param cli_args: Dictionary containing all command-line arguments from user
    :param cur_smooth: String, cli_args key mapped to current smoothing value
    :return: Float; add sigma (surface or volume) round
    """
    add_smooth = math.sqrt((cli_args['spat_smooth']**2)
                           - (cli_args[cur_smooth]**2))
    return round((add_smooth / (2 * (math.sqrt(2 * math.log(2))))), 7)