You will see that I have added some new controls to this display. The Action buton now has a companion called "Cut". This is because I have turned over to you the decision as to when to stop the plotting. In the previous displays the program plotted only for a fixed time. In this display, since you might want to see something that takes a while to develop, plotting will continue until you stop it.

A new menu control will give you a choice of which representation of the pendulum you wish to see. We will open the display window with the Real Space view. The other views available at this point are the Position/Velocity vs Time, Phase Space Projection, and Phase Space Orbit.

The Position/Velocity vs Time representation is similar to the first plot you saw where the plot appeared under the pendulum. In this case the time axis runs horizontally, with position and velocity plotted vertically. The limits on the variables are displayed in the left border for the vertical axis and in the bottom border for horizontal axis. The position of the mouse cursor is shown by a number at the center of the bottom border representing the distance along the horizontal axis, and a number in the left border representing the distance along the vertical axis. The plot will halt when time exceeds the upper limit shown. Another click on Action will move the plotting window up the time axis and plot the next segment. A click on the mouse button with the cursor in the drawing area of the display will mark the cursor point on the screen and record the coordinates of the marked point on the borders.

The Phase Space Projection view is laid out similar to the one just described. The exception is that time is not explicitly plotted so the coordinate axes are the state variables and the action is continuous until halted by clicking the Cut button.

The Phase Space Orbit view is the same as we have been seeing in some of the earlier displays.

If you watch closely you may detect the little kick every time the pendulum completes a cycle by returning to the far right position. Try each of the views to get familiar with the different representations.