public virtual void test_recoverVolatility()
{
int nSteps = TREE_DATA.NumberOfSteps;
double spot = TREE_DATA.Spot;
double timeToExpiry = TREE_DATA.getTime(nSteps);
double dfDom = RATE_PROVIDER.discountFactors(USD).discountFactor(timeToExpiry);
double dfFor = RATE_PROVIDER.discountFactors(EUR).discountFactor(timeToExpiry);
double forward = spot * dfFor / dfDom;
for (int i = 0; i < 100; ++i)
{
double strike = spot * (0.8 + 0.004 * i);
OptionFunction func = EuropeanVanillaOptionFunction.of(strike, timeToExpiry, PutCall.CALL, nSteps);
double price = TREE.optionPrice(func, TREE_DATA);
double impliedVol = BlackFormulaRepository.impliedVolatility(price / dfDom, forward, strike, timeToExpiry, true);
double orgVol = VOLS.volatility(FX_PRODUCT.CurrencyPair, timeToExpiry, strike, forward);
assertEquals(impliedVol, orgVol, orgVol * 0.1); // large tol
double priceMrkt = TREE.optionPrice(func, TREE_DATA_MRKT);
double impliedVolMrkt = BlackFormulaRepository.impliedVolatility(priceMrkt / dfDom, forward, strike, timeToExpiry, true);
double orgVolMrkt = VOLS_MRKT.volatility(FX_PRODUCT.CurrencyPair, timeToExpiry, strike, forward);
assertEquals(impliedVolMrkt, orgVolMrkt, orgVolMrkt * 0.1); // large tol
}
}