Метод ломаных

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApp5

{
class Program
{
public static double F(double x1, double x2)
{
return 211 * x1 * x1 - 420 * x1 * x2 + 211 * x2 * x2 - 192 * x1 + 50 * x2 -25;
}
public static double F(double[] x)
{
return 211 * x[0] * x[0] - 420 * x[0] * x[1] + 211 * x[1] * x[1] - 192 * x[0] + 50 * x[1] - 25;
}
private static double[] GetGradient(double x1, double x2)
{
double[] result = new double[2];
result[0] = 211 * 2 * x1 - 420 * x2 - 192;
result[1] =  211 * 2 * x2 - 420* x1 + 50;
return result;
}
private static double GetSum(double[] gradient)
{
return Math.Sqrt(gradient[0] * gradient[0] + gradient[1] * gradient[1]);
}
private static double[] GetGradientMethod()
{
double eps = 0.01;
double alpha = 10;
double[] x = new double[2];
x[0] = 10;
x[1] = 10;
double fx = F(x);
double[] GradF = GetGradient(x[0], x[1]);
if (Math.Abs(GetSum(GradF)) <= eps)
{
return x;
}
double fy;
double[] y = new double[2];
while (Math.Abs(GetSum(GradF)) > eps)
{
y[0] = x[0] - alpha * GradF[0];
y[1] = x[1] - alpha * GradF[1];
GradF = GetGradient(x[0], x[1]);
fy = F(y);
if (fy < fx)
{
x = y;
fx = fy;
}
else
{
alpha /= 2;
}
}
Console.WriteLine("Curent: ({0} , {1}\t|\tfunc: {2})", 8.04, -7.76, F(8.04, -7.76));
return x;
}
static void Main(string[] args)
{
double[] X = GetGradientMethod();
Console.WriteLine("Result:\nX:{0} {1}\t\t Y:{2}", X[0], X[1], F(X));
}
}
}