private void timer1_Tick(object sender, EventArgs e)
        {
            dif.start(Convert.ToInt32(NUD_mem_step.Text));
            dif.plot(zedGraphControl1, LB_norm_u1, LB_norm_u2, CB_STAT_SOL.Checked);
            if (is_visible_nu)
            {
                dif.plot_star(zedGraphControl1);
            }

            time        += t * Convert.ToDouble(NUD_mem_step.Text);
            LB_Time.Text = "Текущее время = " + Convert.ToString(time);
            LB_Step.Text = "Слой = " + dif.get_layerNum();
        }