Two methods to calculate and plot a sawtooth function in C#

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;

namespace SawTooth
{
    public partial class Form1 : Form
    {
        private List<PointF> Coords;

        public Form1()
        {
            InitializeComponent();
            Coords = new List<PointF>(); // Make list to store the coordinates of some function
        }

        const int Nterms = 18; // number of term used in sum = n in the formula

        private void PlotPanel_Paint(object sender, PaintEventArgs e)
        {          
            Plot MyPlot = new Plot(this.PlotPanel.Size);           
            MyPlot.PlotAxes(e.Graphics);
            // comment this ou if you want to use second method
            String drawString = string.Format("n = {0} terms used in Fourier summation." , Nterms.ToString()); // Create string to draw.

            Font drawFont = new Font("Arial", 16);          // Create font and brush.
            SolidBrush drawBrush = new SolidBrush(Color.Blue);
            PointF drawPoint = new PointF(10f, 10f);  // Create point for upper-left corner of drawing.
            
            // Draw string to screen.
            MyPlot.DrawString(drawString, drawFont, drawBrush, drawPoint, e.Graphics);

            Coords = SawToothFunc(-10.0, 10.0, Nterms, 0.01); //generate list of x,y coordinates
            //second method
            //MyPlot.SetPlotPort(-10, 10, -5, 5);
            //Coords = SawToothFunc(-10.0, 10.0, 0.01); 
            MyPlot.PlotPoints(Coords, Pens.Black, e.Graphics); //plot the coordinate list, take care of screen transforms.                      
        }

        /// <summary>
        /// Method to calculate a sawtooth function
        /// </summary>
        /// <param name="Xlow">The lower boundary value on the X axis</param>
        /// <param name="Xhigh">The higher boundary value on the X axis</param>
        /// <param name="NSums">The number of terms used, higher values give better aproximations</param>
        /// <param name="step">stepvalue of x used in the Xlow XHigh interval</param>
        /// <returns>A list of PointF structures, containing the calculated coordinates </returns>
        private List<PointF> SawToothFunc(double Xlow, double Xhigh, int NSums, double step)
        {
            List<PointF> CoordList = new List<PointF>();
            CoordList.Clear();
           
            int UnityFactor;
            for (double x = Xlow; x <= Xhigh; x += step)
            {
                PointF P = new PointF();
                P.X = (float)x;
                P.Y = 0f;
                UnityFactor = 1;
                for (int n = 1; n <= NSums; n++)
                {
                    // could use Math.Pow(-1.0, n + 1) here to reflect the syntax of the formula a bit more
                    // but the UnityFactor trick uses far less computer time!
                    P.Y += (float)(2 * UnityFactor * Math.Sin(n * x) / n);
                    UnityFactor = -UnityFactor;
                }
                CoordList.Add(P);          
            }
            return CoordList;
        }

        /// <summary>
        /// Another method (without a series approximation) to calculate a Sawtooth function
        /// </summary>
        /// <param name="Xlow">The lower boundary value on the X axis</param>
        /// <param name="Xhigh">The higher boundary value on the X axis</param>
        /// <param name="step">stepvalue of x used in the Xlow XHigh interval</param>
        /// <returns></returns>
        private List<PointF> SawToothFunc(double Xlow, double Xhigh, double step)
        {
            List<PointF> CoordList = new List<PointF>();
            CoordList.Clear();

            for (double t = Xlow; t <= Xhigh; t += step)
            {
                PointF P = new PointF();
                P.X = (float)t;

                double a = 2; 
                
                P.Y = (float)(2 * (t / a - Math.Floor(t / a + 0.5)));
                                 
                CoordList.Add(P);
            }
            return CoordList;
        }
    }
}

/*---------------------------------------------------------------------------
  
  PLOT CLASS
  By DM, last edit : 2/2/2012
  Version 3.00

  If I can find the time I will extend this.
  --------------------------------------------------------------------------*/
using System;
using System.Collections.Generic;
using System.Drawing;

namespace SawTooth
{
    /// <summary>
    /// class to plot x and y values on a Form or Panel
    /// 
    /// Because on the form coordinates start at the upper left corner with 0,0
    /// with the y coordinate going down, a little transformation is done here
    /// so that x,y coordinates act as normal carthesian coordinates, with 0,0
    /// in the center of the Form or Panel
    /// </summary>
    class Plot
    {
        struct PlotPort
        {
            public int minX;
            public int maxX;
            public int minY;
            public int maxY;
        };

        private PlotPort _PlotW;    //"window" of carthesian coordinates
        private Size _ClientArea;   //keeps the screen pixels info
        private float _Xspan;
        private float _Yspan;

        public Plot() 
        {
            _ClientArea = new Size(50,  50); //default width,height
            SetPlotPort(-10, 10, -10, 10);   //default, sets the PlotPort struct
            AxisColor = Color.Red;
        }

        public Plot(Size Plotarea) : this()
        {
            _ClientArea = Plotarea;            
        }

        public Color AxisColor { get; set; }

        public Size ClientArea { set { _ClientArea = value; } }

        /// <summary>
        /// Set the bounderies of the form(screen) to real(world) coordinates.
        /// </summary>
        /// <param name="minx">lowest x value</param>
        /// <param name="maxx">highest x value</param>
        /// <param name="miny">lowest y value</param>
        /// <param name="maxy">highest y value</param>
        public void SetPlotPort(int minx, int maxx, int miny, int maxy)
        {
            //set the bounderies of the form(screen) to real coordinates.
            _PlotW.minX = minx;
            _PlotW.maxX = maxx;
            _PlotW.minY = miny;
            _PlotW.maxY = maxy;
            _Xspan = _PlotW.maxX - _PlotW.minX;
            _Yspan = _PlotW.maxY - _PlotW.minY;
        }

        public void PlotPixel(PointF P, Color C, Graphics G)
        {
            //Plot one pixel
            Bitmap bm = new Bitmap(1, 1);
            bm.SetPixel(0, 0, C);
            P = ToScreen(P);
            G.DrawImageUnscaled(bm, (int)P.X, (int)P.Y); string s = Convert.ToString("astr");
        }

        public void PlotAxes(Graphics G)
        {
            Pen AxisPen = new Pen(Color.Red);
            AxisPen.DashStyle = System.Drawing.Drawing2D.DashStyle.Dash;
            // X-Axis
            PointF X0 = new PointF( _PlotW.minX, _PlotW.minY + _Yspan / 2f);
            PointF X1 = new PointF( _PlotW.maxX, _PlotW.minY + _Yspan / 2f);
            //Y-Axis
            PointF Y0 = new PointF(_PlotW.minX + _Xspan / 2f, _PlotW.maxY);
            PointF Y1 = new PointF(_PlotW.minX + _Xspan / 2f, _PlotW.minY);

            G.DrawLine(AxisPen, ToScreen(X0), ToScreen(X1));
            G.DrawLine(AxisPen, ToScreen(Y0), ToScreen(Y1));

        }

        /// <summary>
        /// Plot a list of carthesian points on the screen
        /// </summary>
        /// <param name="thePts"></param>
        /// <param name="G"></param>
        public void PlotPoints(List<PointF> thePts,Pen P, Graphics G)
        {
            PointF[] PtAr = thePts.ToArray();
            for (int k = 0; k < PtAr.Length; k++)
            {
                PtAr[k] = ToScreen(PtAr[k]);
            }
            G.DrawLines(P, PtAr);
        }

        /// <summary>
        /// Transform a point in carthesian coordinates to a point on the screen
        /// </summary>
        /// <param name="ptC">The point in carthesian(world) coordinates</param>
        /// <returns>Transformed point to be plotted on the screen</returns>
        private PointF ToScreen(PointF ptC)
        {
            PointF aP = new PointF();
            aP.X = _ClientArea.Width / _Xspan * ptC.X + _ClientArea.Width / 2f;
            aP.Y = -(_ClientArea.Height / _Yspan * ptC.Y - _ClientArea.Height / 2f);
            return aP;
        }

        /// <summary>
        /// Print a string in the drawing area
        /// </summary>
        /// <param name="str">The string to print</param>
        /// <param name="fnt"></param>
        /// <param name="br"></param>
        /// <param name="drawPnt">The coordinate of the lefttop corner of the font where printing starts</param>
        /// <param name="G"></param>
        public void DrawString(String str,Font fnt, Brush br, PointF drawPnt, Graphics G)
        {
            G.DrawString(str, fnt, br, drawPnt);
        }
    }
}