I recently downloaded SymPy and was looking to contribute to the stats module. I noticed a few things.
1) The Geometric and Poisson random variable types exist in the drv_types.py file, and I'm able to use them in code, but they aren't mentioned in the documentation ( http://docs.sympy.org/latest/modules/stats.html) as far as I can tell. I would be willing to add these to the docs if they should be there. 2) The expected value calculation E() seems to take a long time for certain types, like Binomial. For example, >>> X = Binomial("x", 10000, S.Half) >>> E(X) takes quite a while (over 10 seconds on my computer). Not sure if this is some weird issue with my setup, or an inefficiency in the code. If it's an inefficiency, we should think about providing built-in expected value formulas for common types like Binomial (which has a very simple formula that should return almost immediately even for large values). 3) There isn't a Negative Binomial ( http://en.wikipedia.org/wiki/Negative_binomial_distribution) random variable type. I've written code that implements it, I believe, if we want to include it in SymPy. Let me know your thoughts on any or all of these points! -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at http://groups.google.com/group/sympy. For more options, visit https://groups.google.com/groups/opt_out.
