title: I got an IndexError: list index out of range in sys.argv[1]
body: <p>I want to plot this code but it entered </p>
  
  <blockquote>
    <p>IndexError: list index out of range in the line: k =
    float(sys.argv[1])</p>
  </blockquote>
  
  <p>Can anyone help me how to fix this?</p>
  
  <pre><code>canWidth=500
  canHeight=500
  **strong text**
  def setupWindow () :
      global win, canvas
      from tkinter import Tk, Canvas, Frame
      win = Tk()
      canvas = Canvas(win, height=canHeight, width=canWidth)
      f = Frame (win)    
      canvas.pack()
      f.pack()
  
  def startApp () :
      global win, canvas
      import sys
      k1  = float(sys.argv[1])   # starting value of K
      k2  = float(sys.argv[2])   # ending   value of K
      x = .2                     # is somewhat arbitrary
      vrng = range(200)          # We'll do 200 horz steps
      for t in range(canWidth) :
          win.update()
          k = k1 + (k2-k1)*t/canWidth
          print ("K = %.04f" % k)
          for i in vrng :
              p = x*canHeight
              canvas.create_line(t,p,t,p+1)  # just makes a pixel dot
              x = x * (1-x) * k              # next x value
              if x &lt;=0 or x &gt;= 1.0 :
                  print ("overflow at k", k)
                  return
  
  def main () :
      setupWindow()       # Create Canvas with Frame
      startApp()          # Start up the display  
      win.mainloop()      # Just wait for user to close graph
  
  if __name__ == "__main__" : main()
  </code></pre>