Add operation

[Henrique Miguel Cortes Soares]

Why does type(Add(A, B)), where A and B are MatrixSymbols, return MatAdd but type(Add(Sys.i, Sys.j)), where Sys.i, Sys.j are BaseVectors, return Add and not VectorAdd?

Doing type(Sys.i + Sys.j) also returns VectorAdd

[Sangyub Lee]

I think that this question is quite technical, but I may take a chance to answer this

I think that you may try to fix this by adding constructor_postprocessor_mapping to corresponding vector module, as done by matrix

https://github.com/sympy/sympy/blob/8c94201570737a2fc3ef8e9cc53bed01a44e8281/sympy/matrices/expressions/matexpr.py#L525-L528

However, I'd note that constructor_postprocessor_mapping is already commented to be 'experimental' from the author,
and if the issue cannot be fixed with the simple change like this
(SymPy community have historical experiences that lots of tests can fail for making small changes, for example)
we may be better not involved in pushing this changes.