My main problem with SymPy is that I don't know where its community is! Maxima has a mailing list that is a really lovely place and an IRC channel that is (halfway between dead and) alive... what are the good places to ask questions about Sympy? Stackoverflow? Matrix? I just discovered that it has a group in Google Groups - that, ta-da! even has a recent message about the Gitter channel:

https://groups.google.com/g/sympy/c/jisKFe_xsd0

"From what I've seen, for a while, it's mostly just been people asking questions, but no one has been on there who is actually able to answer them."