Discussion about the stationnary/summa variants

The following discussion from !336 (merged) should be addressed:

• @agullo started a discussion:

  Minor remark about the naming, which shall not prevent merge at it can be modified later on. Do we want ChamGemmAlgSummaA or something like ChamGemmAlgAstat. Whether or not it becomes SUMMA depends on the used back-end and how collective communications are employed.

  And we might have another variable (for instance ChamGemmAlgExplicitSumma=ON/OFF) to switch to the variant where SUMMA is forced by explicit copies (when this variant is implemented, which might be worth keeping for matrix products, as we have them at least in the C-stationnary case). ALternatively, if we want to keep a single variable alg, then we could have ChamGemmAlgAstat, ChamGemmAlgBstat, ChamGemmAlgCstat, ChamGemmAlgAuto and ChamGemmAlgCstatForceSumma, where the latter one would be the variant that implements SUMMA with explicit copies (the current chameleon_pzgemm_summa and chameleon_pzhemm_summa routines).

  What do you think?

I honestly don't know. That's a good question in fact and we should discuss this. I was wondering too for the naming of the routine in the pz{ge,sy,he}mm.c files as indeed these are two orthogonal features (summa or the way the communications are done, and which matrix is stationary )

Thanks for making it an issue. Perfect for taking the time to discuss it.