public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            double xmin = double.Parse(textBox1.Text);
            double xmax = double.Parse(textBox2.Text);
            double step = double.Parse(textBox3.Text);
            int count = (int)Math.Ceiling((xmax - xmin) / step) + 1;
            double[] x = new double[count];
            double[] y1 = new double[count];
            double[] y2 = new double[count];
            for (int i = 0; i < count; i++)
            {
                x[i] = xmin + step * i;
                y1[i] = Math.Pow(x[i], 4) + Math.Cos(2 + Math.Pow(x[i], 3) - 1.3);
                y2[i] = Math.Sqrt(Math.Pow(x[i], 4) + Math.Cos(2 + Math.Pow(x[i], 3) - 1.3));
            }
            chart1.ChartAreas[0].AxisX.Minimum = xmin;
            chart1.ChartAreas[0].AxisX.Maximum = xmax;
            chart1.ChartAreas[0].AxisX.MajorGrid.Interval = step;
            chart1.Series[0].Points.DataBindXY(x, y1);
            chart1.Series[1].Points.DataBindXY(x, y2);
        }