inline
 Real OptionletVolatilityStructure::blackVariance(const Period& optionTenor,
                                                  Rate strike,
                                                  bool extrapolate) const {
     Date optionDate = optionDateFromTenor(optionTenor);
     return blackVariance(optionDate, strike, extrapolate);
 }
 inline
 Real SwaptionVolatilityStructure::blackVariance(const Period& optionTenor,
                                                 Time swapLength,
                                                 Rate strike,
                                                 bool extrapolate) const {
     Date optionDate = optionDateFromTenor(optionTenor);
     return blackVariance(optionDate, swapLength, strike, extrapolate);
 }