math_task1

import static java.lang.Math.abs;

public class SumFunc {
    private static final double EPS = 1e-6;

    public static void main(String[] args) {
        double V = 3;
        double a = -1;
        double b = 1;
        double step = 0.2;
        for (double x = a; x < b; x += step) {
            double[] func = func(V, x);
            System.out.printf("%f\t%f\t%d\n", x, func[0], (int) func[1]);
        }
    }

    public static double next(double cur, double c, double pow) {
        double next = cur * c * c / (pow * (pow - 1));
        return -1 * next;
    }

    public static double[] func(double V, double x) {
        double pow = 2;
        double cur = 1;
        double sum = cur;
        double next = next(cur, V * x, pow);
        int count = 1;

        while (abs(next) >= EPS) {
            count++;
            sum += next;
            pow += 2;
            cur = next;
            next = next(cur, V * x, pow);
        }

        return new double[]{sum, count};
    }
}