def bond_coupon(couponRate, facevalue=1000.0):
    """
    Calculates the Coupon Value

    :param couponrate: Coupon interest rate % a.a for a brazilian bond that pays twice per year.
    :param facevalue:  Face Value of one bond, default 1000.0
    :return:
    """
    couponRate = (1 + couponRate) ** 0.5 - 1
    return round(facevalue * couponRate, 2)