Knotplot

You can download knotplot, or you can play with it on the system at the University of Utah mathematics department. Just type in

knotplot

Click on button "1" in the first row of buttons. This will load a random knot. Or type "load 9.46" in the console to load knot 9.46.

Even though there are no (good) algorithms to tell if a knot is really an unknot, there are some very interesting pseudo-algorithms. To get a feel for one of them, click on "demos" on the right panel and then "load Nasty, go Nasty".

Pictures on this page were produced by typing "ppmout foo 1" in the console, which saves the current picture in the main window in the ppm format as foo.ppm ("1" means highest resolution), and then converting to png format for display on the web using gimp (you can also use commercial software if you feel like it!)

A much more detailed tutorial/manual is available online at http://www.pims.math.ca/knotplot/manual/KnotPlotManual.html and it can also be obtained in pdf format from the knotplot site.