So I am reading up on python in Mark Lutz's wonderful LEARNING PYTHON book. Mark makes a big deal about how part of the python development philosophy is polymorphism and that functions and code should rely on polymorphism and not do much type checking. However, I do a lot of math type programming and so the idea of polymorphism does not really seem to apply--I don't want to try and run a regression on a string or something. So I was wondering if there is something I am missing here. What are the applications of polymorphism when I am writing functions for math--or is type checking philosophically okay in this case. 
how to follow python polymorphism standards with math functions
python;polymorphism