public static void trapezia(){


        double yi1 = 0;
        double yi = y0;
        double xi = x0;

        point2.add(new Point(xi,yi));

        for(int i = 1;i < N + 1;i++){

            double yiCurr = yi;
            double yiPrev = yi;

            do{
                yiPrev = yiCurr;
                yiCurr = yiPrev - (yiPrev - yi - 0.5 * h * (f(xi,yi) + f(xi + h,yiPrev))) / (1 - 0.5 * h * f1(xi + h,yiPrev));
            }
            while(Math.abs(yiCurr - yiPrev) > 0.0000001);

            yi1 = yi + 0.5 * h * (f(xi,yi) + f(xi + h,yiCurr));

            yi = yi1;
            xi = x0 + i * h;

            point2.add(new Point(xi,yi));
        }

    }