This is a simple example using interactive 3-dimensional graphics:

Instructions: put cursor into graphics window, and with left button pressed, drag the cursor. The knot shown will rotate. There are three other things one can do: translate, scale, and reset. To do these use pop-up menu at top of frame. The translating and scaling are done by dragging the cursor in the window as with rotation.

NOTE: the software used here is the JGV viewer available from the Geometry Center at