ABA_Matrix dimension mismatch for sparse matrix and axes

[akody]

When running "PNM.ABA_Matrix(sys)" specifically for the RTS GMLC test network, I get a mismatch in the size of the sparse matrix and the length of the axes. See screenshot.

[jd-lara]

@akody this is expected since the ABA matrix doesn't have the slack bus. Indexing is allowed but it will return an error.

[akody]

@jd-lara According to the struct description of ABA_Matrix here, the field "axes" is a "Tuple containing two identical vectors, both containing the number of each bus of the network (each one related to a row/column of the Matrix in "data"), excluding the slack buses."

However, in my example, ABA_Matrix.axes does not contain vectors with the same number of rows/columns as ABA_Matrix.data, and the vectors in ABA_Matrix.axes contain the reference bus.

Let me know if I am misunderstanding something here.

Note: It looks like there are separate ACBusTypes for SLACK and REF; however, ABA_Matrix(.) seems to remove the REF buses using functions calculate_A_matrix(.) and find_slack_positions(.)

[jd-lara]

you are right, we should improve this docstring and descriptor. Up to now not many people use these matrices outside of the PTDF/LODF calculations so we haven't payed too much attention to them