WFA_psychometric_chart.Form1_main.marker_for_same_min_max_value C# (CSharp) Method

        private void marker_for_same_min_max_value()
        {
            /*
            Our previous marker formula has a draw back if max_value = min_value the difference 
            between max_value- min_value=0 so which present problem 
            this is solved by this marker assumin in such case the plot is of same color we do this part.
            */

            
            try
            {
                using (Graphics grp1 = this.CreateGraphics())
                {

                    int x1Axis = (int)(chart1.ChartAreas[0].Position.X + chart1.Width + 10);
                    int y1Axis = (int)(chart1.ChartAreas[0].Position.Y + chart1.Height);

                    int x2Axis = x1Axis + 15;
                    int y2Axis = y1Axis;

                    double start = min_value;

                    double value = start;
                    // double temp_value = (max_value - min_value);
                    //double increment = 0;
                    //increment = temp_value / 50;


                    //decimal val = (Decimal)((value - min_value) / (max_value - min_value));

                    Pen pen1 = new Pen(Color.FromArgb(0, 255, 0));
                    //grp1.DrawRectangle(pen1, 958, 537, 15, 15);
                    grp1.DrawRectangle(pen1, x1Axis, y1Axis, 15, 15);

                    SolidBrush drawBrushGreen = new SolidBrush(Color.FromArgb(0, 255, 0));
                    //grp1.FillRectangle(drawBrushGreen, 958, 537, 15, 15);
                    grp1.FillRectangle(drawBrushGreen, x1Axis, y1Axis, 15, 15);

                    String drawString = Math.Round(value,0).ToString();
                    // Create font and brush.
                    Font drawFont = new Font("Arial", 7);
                    SolidBrush drawBrush = new SolidBrush(Color.Black);
                    // Create point for upper-left corner of drawing.
                    PointF drawPoint = new PointF(x1Axis-12, y1Axis);//--537->520
                    // Draw string to screen.
                    grp1.DrawString(drawString, drawFont, drawBrush, drawPoint);
                }

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
        private void marker()