class Ex060921f_newton{
	double initialval;
	double eps;
	double x0,x1;
	Ex060921f_func fn;
	
	Ex060921f_newton(){
		initialval=1.0;
		eps=1.0e-15;
		 fn = new Ex060921f_func();
	}
	
	Ex060921f_newton(double iv, double es){
		initialval=iv;
		eps=es;
		fn = new Ex060921f_func();
	}
	
	public double ans(){
		x1=initialval;
		do{
			x0=x1;
			x1=x0-fn.f(x0)/fn.diff(x0);
		}while(Math.abs(x1-x0)>eps);
		return(x1);
	}
}