){
        min_d = Math.pow(runge_xs[0] - client_to_x(client_x), 2) + Math.pow(runge_ys[0] - client_to_y(client_y), 2);
        min_i = 0;
        for(var i = 1; i < runge_n; ++i){
            var di = Math.pow(runge_xs[i] - client_to_x(client_x), 2) + Math.pow(runge_ys[i] - client_to_y(client_y), 2);
            if(di < min_d){
                min_d = di;
                min_i = i;
            }
        }
        runge_i = min_i;
        runge_context.setLineDash([4, 4]);
        runge_context.beginPath();