public static Vector CalculateRootWithConjugateGradientMethod(Gradient gradient, Vector rootPoint)
{
Vector previousCalculatedRoot = new Vector(new double[rootPoint.Size]);
Vector gradientResult = gradient.Solve(rootPoint[0], rootPoint[1]);
d = new Vector(new double[] { -1, -1 });
sigma = 0.5;
while (!gradientResult.Equals(new Vector(new double[] { 0, 0 })))
{
CalculateDescentDirection(gradient, rootPoint, sigma, d);
previousCalculatedRoot = rootPoint;
rootPoint = LinearAlgebraOperations.AddVectorToVector(rootPoint, LinearAlgebraOperations.MultiplyVectorWithScalar(d, sigma));
gradientResult = gradient.Solve(rootPoint[0], rootPoint[1]);
}
return(rootPoint);
}
private static void CalculateDescentDirection(Gradient gradient, Vector currentGuessedRoot, double sigma, Vector d)
{
Vector xkPlusSigmaKTimesDk = LinearAlgebraOperations.AddVectorToVector(currentGuessedRoot, LinearAlgebraOperations.MultiplyVectorWithScalar(d, sigma));
double normalFunctionResult = gradient.func.Solve(currentGuessedRoot[0], currentGuessedRoot[1]);
double changeFunctionResult = gradient.func.Solve(xkPlusSigmaKTimesDk[0], xkPlusSigmaKTimesDk[1]);
while (changeFunctionResult > normalFunctionResult && sigma > 0 &&
(d[0] < 0 && d[1] < 0))
{
xkPlusSigmaKTimesDk = LinearAlgebraOperations.AddVectorToVector(currentGuessedRoot, LinearAlgebraOperations.MultiplyVectorWithScalar(d, sigma));
normalFunctionResult = gradient.func.Solve(currentGuessedRoot[0], currentGuessedRoot[1]);
changeFunctionResult = gradient.func.Solve(xkPlusSigmaKTimesDk[0], xkPlusSigmaKTimesDk[1]);
sigma -= 0.05;
for (int i = 0; i < d.Size; i++)
{
d[i] += 0.05;
}
}
}