private void priceCheck(double[] strikes)
{
for (int i = 0; i < N; i++)
{
double ivNormalComputed = NormalFormulaRepository.impliedVolatilityFromBlackApproximated(FORWARD, strikes[i], T, SIGMA_BLACK[i]);
double priceNormalComputed = NormalFormulaRepository.price(FORWARD, strikes[i], T, ivNormalComputed, PutCall.CALL) * DF;
double priceBlack = BlackFormulaRepository.price(FORWARD, strikes[i], T, SIGMA_BLACK[i], true) * DF;
assertEquals(priceNormalComputed, priceBlack, TOLERANCE_PRICE);
}
}
//-------------------------------------------------------------------------
/// <summary>
/// Computes the implied volatility.
/// <para>
/// If the volatility data is not zero, it is used as a starting point for the volatility search.
/// </para>
/// <para>
/// Note that the 'numeraire' is a simple multiplier and is the responsibility of the caller.
///
/// </para>
/// </summary>
/// <param name="optionPrice"> the price of the option </param>
/// <param name="forward"> the forward value of the underlying </param>
/// <param name="strike"> the strike </param>
/// <param name="timeToExpiry"> the time to expiry </param>
/// <param name="initialNormalVol"> the normal volatility used to start the search </param>
/// <param name="numeraire"> the numeraire </param>
/// <param name="putCall"> whether it is put or call </param>
/// <returns> the implied volatility </returns>
public static double impliedVolatility(double optionPrice, double forward, double strike, double timeToExpiry, double initialNormalVol, double numeraire, PutCall putCall)
{
double intrinsicPrice = numeraire * Math.Max(0, (putCall.Call ? 1 : -1) * (forward - strike));
ArgChecker.isTrue(optionPrice > intrinsicPrice || DoubleMath.fuzzyEquals(optionPrice, intrinsicPrice, 1e-6), "Option price (" + optionPrice + ") less than intrinsic value (" + intrinsicPrice + ")");
if (System.BitConverter.DoubleToInt64Bits(optionPrice) == Double.doubleToLongBits(intrinsicPrice))
{
return(0d);
}
double sigma = (Math.Abs(initialNormalVol) < 1e-10 ? 0.3 * forward : initialNormalVol);
double maxChange = 0.5 * forward;
ValueDerivatives price = priceAdjoint(forward, strike, timeToExpiry, sigma, numeraire, putCall);
double vega = price.getDerivative(1);
double change = (price.Value - optionPrice) / vega;
double sign = Math.Sign(change);
change = sign * Math.Min(maxChange, Math.Abs(change));
if (change > 0 && change > sigma)
{
change = sigma;
}
int count = 0;
while (Math.Abs(change) > EPS)
{
sigma -= change;
price = priceAdjoint(forward, strike, timeToExpiry, sigma, numeraire, putCall);
vega = price.getDerivative(1);
change = (price.Value - optionPrice) / vega;
sign = Math.Sign(change);
change = sign * Math.Min(maxChange, Math.Abs(change));
if (change > 0 && change > sigma)
{
change = sigma;
}
if (count++ > MAX_ITERATIONS)
{
BracketRoot bracketer = new BracketRoot();
BisectionSingleRootFinder rootFinder = new BisectionSingleRootFinder(EPS);
System.Func <double, double> func = (double?volatility) =>
{
return(numeraire * NormalFormulaRepository.price(forward, strike, timeToExpiry, volatility.Value, putCall) - optionPrice);
};
double[] range = bracketer.getBracketedPoints(func, 0d, 10d);
return(rootFinder.getRoot(func, range[0], range[1]).Value);
}
}
return(sigma);
}
public virtual void implied_volatility_adjoint()
{
double shiftFd = 1.0E-6;
for (int i = 0; i < N; i++)
{
double impliedVol = NormalFormulaRepository.impliedVolatilityFromBlackApproximated(FORWARD, STRIKES[i], T, SIGMA_BLACK[i]);
ValueDerivatives impliedVolAdj = NormalFormulaRepository.impliedVolatilityFromBlackApproximatedAdjoint(FORWARD, STRIKES[i], T, SIGMA_BLACK[i]);
assertEquals(impliedVolAdj.Value, impliedVol, TOLERANCE_VOL);
double impliedVolP = NormalFormulaRepository.impliedVolatilityFromBlackApproximated(FORWARD, STRIKES[i], T, SIGMA_BLACK[i] + shiftFd);
double impliedVolM = NormalFormulaRepository.impliedVolatilityFromBlackApproximated(FORWARD, STRIKES[i], T, SIGMA_BLACK[i] - shiftFd);
double derivativeApproximated = (impliedVolP - impliedVolM) / (2 * shiftFd);
assertEquals(impliedVolAdj.Derivatives.size(), 1);
assertEquals(impliedVolAdj.getDerivative(0), derivativeApproximated, TOLERANCE_VOL);
}
}
/// <summary>
/// Computes vega of an option in the normally distributed assets hypothesis (Bachelier model).
/// </summary>
/// <param name="option"> the option description </param>
/// <param name="data"> the model data </param>
/// <returns> vega </returns>
public double getVega(EuropeanVanillaOption option, NormalFunctionData data)
{
ArgChecker.notNull(option, "option");
ArgChecker.notNull(data, "data");
return(data.Numeraire * NormalFormulaRepository.vega(data.Forward, option.Strike, option.TimeToExpiry, data.NormalVolatility, option.PutCall));
}
/// <summary>
/// Computes the price of an option in the normally distributed assets hypothesis (Bachelier model).
/// The first order price derivatives are also provided.
/// </summary>
/// <param name="option"> the option description </param>
/// <param name="data"> the model data </param>
/// <returns> a <seealso cref="ValueDerivatives"/> with the price in the value and the derivatives with
/// respect to [0] the forward, [1] the volatility and [2] the strike </returns>
public ValueDerivatives getPriceAdjoint(EuropeanVanillaOption option, NormalFunctionData data)
{
ArgChecker.notNull(option, "option");
ArgChecker.notNull(data, "data");
return(NormalFormulaRepository.priceAdjoint(data.Forward, option.Strike, option.TimeToExpiry, data.NormalVolatility, data.Numeraire, option.PutCall));
}
//JAVA TO C# CONVERTER TODO TASK: Most Java annotations will not have direct .NET equivalent attributes:
//ORIGINAL LINE: @SuppressWarnings("synthetic-access") @Override public System.Nullable<double> apply(NormalFunctionData data)
public override double?apply(NormalFunctionData data)
{
ArgChecker.notNull(data, "data");
return(data.Numeraire * NormalFormulaRepository.price(data.Forward, option.Strike, option.TimeToExpiry, data.NormalVolatility, option.PutCall));
}
//JAVA TO C# CONVERTER TODO TASK: Most Java annotations will not have direct .NET equivalent attributes:
//ORIGINAL LINE: @Test(expectedExceptions = IllegalArgumentException.class) public void wrong_forward()
public virtual void wrong_forward()
{
NormalFormulaRepository.impliedVolatilityFromBlackApproximated(-1.0d, FORWARD, T, 0.20d);
}
//JAVA TO C# CONVERTER TODO TASK: Most Java annotations will not have direct .NET equivalent attributes:
//ORIGINAL LINE: @Test(expectedExceptions = IllegalArgumentException.class) public void wrong_strike()
public virtual void wrong_strike()
{
NormalFormulaRepository.impliedVolatilityFromBlackApproximated(FORWARD, -1.0d, T, 0.20d);
}
private double impliedVolatility(NormalFunctionData data, EuropeanVanillaOption option, double price)
{
return(NormalFormulaRepository.impliedVolatility(price, data.Forward, option.Strike, option.TimeToExpiry, data.NormalVolatility, data.Numeraire, option.PutCall));
}
