C#

public class PipeSection
{
    public PipeSection(double radius)
    {
        this.Radius = radius;
    }

    public double Radius { get; set; }


    public double Calculate(double Frequency)
    {
        return Frequency * this.Radius;
    }

}

CancellationTokenSource ctr = new CancellationTokenSource();
       List<PipeSection> wn = new List<PipeSection>();

       public MainWindow()
       {
           InitializeComponent();

           PipeSection[] input = { new PipeSection(5), new PipeSection(6), new PipeSection(7) };

           wn.AddRange(input);

           //Calcualte at the frequencies 0,100,2000,3000
           var FreqData = new double[] { 0, 100, 2000, 3000 }.ToObservable<double>();

           FreqData
               //Off the ui thread
               .ObserveOn(Scheduler.Default)
               //Run each thread seperatly
               .SelectMany(x => Task.Run<double>(() => DoCalcualtions(x,wn), ctr.Token))
               //Back to the UI thread
               .ObserveOnDispatcher()
               //Subscribe and start the calcualtions
               .Subscribe(args => {
                                   //Update the progressbar when a thread is completed
                                   pgbProgress.Value += 1;
                                   //Tell me what thread is completed
                                   txtText.Text += Environment.NewLine + args.ToString();
                                   },
                           () => {
                                   //All done, here I could do sorting etc.
                                   txtText.Text += Environment.NewLine + "All done";
                                 }
                           );
       }

       private double DoCalcualtions(double Freq, List<PipeSection> input)
       {
           double result=1;
           for (int i = 0; i < input.Count(); i++)
               result *= input[i].Calculate(Freq);

           return result;
       }

void LoadListView()
{
    int i = 0;
    listView1.LargeImageList = imageList1;

    foreach (string file in fileList)
    {
        Bitmap thumbnail = MakeThumbnail(file, 200, 200);
        imageList1.Images.Add(thumbnail);
        ListViewItem caption = new ListViewItem(Path.GetFileName(file));
        caption.ImageIndex = i;
        listView1.Items.Add(caption);
        i++;
    }
}

Bitmap MakeThumbnail(string filename, int thumbWidth, int thumbHeight)
{
  Bitmap thumbnail = null;
  
  try
  {
    Bitmap bmp = new Bitmap(filename);
    ImageFormat loFormat = bmp.RawFormat;
    decimal ratio;
    int newImgWidth = 0;
    int newImgHeight = 0;

    // If the image is smaller than a thumbnail just return it
    if (bmp.Width < thumbWidth && bmp.Height < thumbHeight)	return bmp;

    if (bmp.Width > bmp.Height)
    {
      ratio = (decimal)thumbWidth / bmp.Width;
      newImgWidth = thumbWidth;
      decimal temp = bmp.Height * ratio;
      newImgHeight = (int)temp;
    }
    else
    {
      ratio = (decimal)thumbHeight / bmp.Height;
      newImgHeight = thumbHeight;
      decimal temp = bmp.Width * ratio;
      newImgWidth = (int)temp;
    }
    
    thumbnail = new Bitmap(thumbWidth, thumbHeight);
    Graphics g = Graphics.FromImage(thumbnail);
    g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
    g.FillRectangle(Brushes.White, 0, 0, thumbWidth, thumbHeight);
    g.DrawImage(bmp,
                (thumbWidth - newImgWidth) / 2,
                (thumbHeight - newImgHeight) / 2,
                newImgWidth, newImgHeight);

    bmp.Dispose();
  }
  catch
  {
    return null;
  }

  return thumbnail;
}