Ok, here´s something to check out besides the GH environment:
http://k3dsurf.sourceforge.net/
Also, here you have the file with some additional curves:
08-mathematics-and-geometry-polar-carthesian_01
And also, the file from today´s lesson:
08-m-g-z-hodny
And also, check the previous entries with this topic:
http://scripting.molab.eu/lectures/mathmenatics-in-gh/
http://scripting.molab.eu/lectures/mathematic-and-geometry/