static double NetwonRaphson() {
		if (f(v, 0) == 0)
			return 0;
		double xn = 0.5, x = 0;
		while (true) {
			x = xn - f(v, xn) / ff(v, xn);
			if (Math.abs(x - xn) < EPS)
				return xn;
			xn = x;
		}
	}