FYI:I'll be speaking at LIMACON SUNY Old Westbury 3/15/13 about using SAGE and python to teach High School preCalculus! http://shadowfaxrant.blogspot.com/2013/03/limacon-2013-looming-large.html HTH, A. Jorge Garcia Applied Math, Physics and CS http://shadowfaxrant.blogspot.com http://www.youtube.com/calcpage2009