Eric Wieser

Sorry, I meant @enkimute!

Should be able to do a (possibly) faster implementation along the lines of ``` return self.subs({ b: b if len(i) % 2 == 0 else -b for i, b in...

> t would be nice if one could include MathJax expressions in these posts There's unfortunately no easy way to put latex in github. My usual strategy is to just...

I think your suggested change of ```diff self.mat = Dictionary_to_Matrix(self.lt_dict, self.Ga) * self.Ga.g - return self.mat + return self.mat * self.Ga.g_inv ``` would solve the problem - but it can...

> But one shouldn't have to do the transposition manually. It should be done automatically before a method call f.matrix() returns its answer. You can make this go away by...

Notebooks need regenerating

> One concern, should we use the private Sympy has not been built for ease of writing extension algebras - we have little choice but to call private methods if...

Found a useful part of the (private) sympy API, `_constructor_postprocessor_mapping` ([example here](https://github.com/sympy/sympy/blob/e359645106eb79856089dcc2d6c6871b63550c97/sympy/core/tests/test_constructor_postprocessor.py)) https://github.com/sympy/sympy/blob/master/sympy/core/basic.py#L1793-L1822 This would allow us to overload `Add(mv, mv)`.

Thanks for the report. It would be helpful in future if you could upload notebooks to gist.github.com so that I can view them without downloading, unzipping, and running the notebook....

I think the underlying confusion is what matrices and their multiplication means in a non-orthogonal metric. A similar issue comes from trying to associate 1-vectors with column matrices:  Clearly....