public static Date referencePeriodStart(Bond bond, Date settlementDate = null)
{
if (settlementDate == null)
{
settlementDate = bond.settlementDate();
}
Utils.QL_REQUIRE(BondFunctions.isTradable(bond, settlementDate), () =>
"non tradable at " + settlementDate +
" (maturity being " + bond.maturityDate() + ")",
QLNetExceptionEnum.NotTradableException);
return(CashFlows.referencePeriodStart(bond.cashflows(), false, settlementDate));
}