public static double sin(double x, double eps) {
        double sum = 0;
        double lastD = -Integer.MAX_VALUE;
        double a = -1;
        double b = x;
        double c = 1;
        double d;
        for (int n = 0; true; n++) {
            a = -a;
            if (n != 0) {
                b *= x*x;
                c *= (2*n*(2*n+1));
            }
            d = b / c;
            if (Math.abs(d - lastD) < eps) break;
            lastD = d;
            sum += a*d;
        }
        return sum;
    }