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 */

package ohlaba3again;

/**
 *
 * @author Гость
 */
public class Ohlaba3again {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
                double a = 0.1;
		double b = 0.8;
		int k = 10;
		int n = 35;
		double delta = (b - a)/k;
		double e = 0.0001;

		for (double i = a; i <= b; i += delta)
		{
			double y_an, y_n, y_e, err_e, err_n;

			y_an = f(i);
			y_n = S(i, n);
			y_e = S(i, e);
			/*err_e = err(y_an, y_e);
			err_n = err(y_an, y_n);*/

			//System.out.printf("X=% 8.8f Y=% 8.8f  SN=% 8.8f SE=% 8.8f  о_погрSN=% 8.8f  о_погрSE=% 8.8f\n", i, y_an, y_n, y_e, err_e, err_n);
                        System.out.printf("X=% 8.8f Y=% 8.8f SN=% 8.8f SE=% 8.8f \n", i, y_an,y_n,y_e);

		}
	}
	public static double f(double x) //Аналитическая формула
	{
          // System.out.println("TEST X: "+ x);
		//double y = ((Math.pow(Math.PI, 2)/8) - (Math.PI/4)*Math.abs(x));
                double y = -0.5*Math.log(1-2*x*Math.cos(Math.PI/3)+Math.pow(x, 2));
		return y;
	}

	public static double S(double x, int n) //Конечная сумма n членов ряда
	{
		double y = 0;
		for (int i = 1; i <= n; i++)
		{
			//y += (Math.cos((2*i - 1)*x))/Math.pow((2*i - 1), 2);
                        y+= Math.pow(x, i)*Math.cos(i*(Math.PI/3));
		}
		return y;
	}

	public static double S(double x, double e) //Конечная сумма с погрешностью e
	{
		double y = 0;
		double y_an = f(x);
			System.out.println("TEST Y_an:" + y_an);
		for (int i = 1; Math.abs(y - y_an) > e; i++)
		{
			//y += (Math.cos((2*i - 1)*x))/Math.pow((2*i - 1), 2);
                        y+= Math.pow(x, i)*Math.cos(i*(Math.PI/3));
                }
		return y;
	}

	public static double err(double y_an, double y) //Относительная погрешность
	{
		return Math.abs((y_an - y)/y_an);
	}
}