import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class GradDescent {
	private static double er = 10E-6;
	private static int mode = 1;	// 0 - pomak nenormirani v.g., 1 - zlatni rez
	public static final Fun f = new F3();

	public static void main(String[] args) throws NumberFormatException, IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		String input = "";
		System.out.println("Mode (default 0):");
		input = in.readLine();
		if (!input.isEmpty()) {
			mode = Integer.parseInt(input);
		}
		System.out.println("Error (default 10E-6):");
		input = in.readLine();
		if (!input.isEmpty()) {
			er = Double.parseDouble(input);
		}
		System.out.println("Starting point:");
		input = in.readLine();
		String[] nums = input.split("\\s+");

		double[] x = new double[nums.length];
		for (int i = 0; i < nums.length; i++) {
			x[i] = Double.parseDouble(nums[i]);
		}

		double[] gradx = f.grad(x);
		double normgradx = norm(gradx);
		int i = 0;
		while (Math.abs(normgradx) > er) {
			System.out.print("x" + i + " = ");
			printVec(x);
			System.out.print("grad x" + i + " = ");
			printVec(gradx);
			System.out.println("norm (grad x" + i + ") = " + normgradx);
			double[] v = smul(-1 / normgradx, gradx);
			System.out.print("v" + i + " = ");
			printVec(v);
			System.out.print("F(x) = " + f.eval(x)+"\n");
			System.out.print("Broj poziva funkcije = " + f.getCallCount()+"\n");
			System.out.print("Broj racunanja gradijenata = " + f.getGradCount()+"\n");
			printVec(x);

			if (mode == 0) {
				x = vecop("+", x, v);
			} else if (mode == 1) {
				System.out.println("~~~~~Zlatni rez~~~~~");
				GSFun gsf = new GSFun();
				gsf._x = x;
				gsf._v = v;
				GoldenSection gs = new GoldenSection(1);
				gs.find(gsf, 1);
				double lambda = (gs.a + gs.b) / 2;
				System.out.println("lambda: " + lambda);
				System.out.print("Broj poziva funkcije = " + f.getCallCount()+"\n");
				System.out.print("Broj racunanja gradijenata = " + f.getGradCount()+"\n");
				System.out.println("~~~~~~~~~~~~~~~~~~~~");

			} else {
				System.out.println("Unknown mode");
				System.exit(0);
			}
			gradx = f.grad(x);
			normgradx = norm(gradx);
			i++;
			printVec(x);
			System.out.print("F(x) = " + f.eval(x)+"\n");
			System.out.println("------------------------");
		}
	}

	private static double norm(double[] x) {
		double sum = 0;

		for (double xi : x) {
			sum += Math.pow(xi, 2);
		}

		return Math.sqrt(sum);
	}

	private static double[] smul(double scalar, double[] vector) {
		double[] res = new double[vector.length];

		for (int i = 0; i < vector.length; i++)
			res[i] = scalar * vector[i];

		return res;
	}

	private static double[] vecop(String op, double[] arg1, double[] arg2) {
		double[] res = new double[arg1.length];

		for (int i = 0; i < res.length; i++) {
			if ("-".equals(op)) {
				res[i] = arg1[i] - arg2[i];
			} else {
				res[i] = arg1[i] + arg2[i];
			}
		}

		return res;
	}

	private static void printVec(double[] v) {
		String ret = "(";
		for (int i = 0; i < v.length; i++)
			ret += v[i] + " ";
		ret.trim();
		ret += ")";
		System.out.println(ret);
	}

	static class GSFun implements Fun {

		public double[] _x;
		public double[] _v;

		@Override
		public double eval(double... x) {
			double lambda = x[0];
			return f.eval(_x[0] + lambda * _v[0], _x[1] + lambda * _v[1]);
		}

		@Override
		public int getCallCount() {
			return 0;
		}
		@Override
		public int getGradCount() {
			return 0;
		}

		@Override
		public void setCallCount(int c) {}

		@Override
		public double[] grad(double... x) {
			return null;
		}

		@Override
		public Matrix hessian(double... x) {
			return null;
		}

	}

}