AMG_Level::Aoriginal not intuitive

It took me quite a while to figure out what's the point of AMG_Level::Aoriginal. In constructor A and Aoriginal are set to point to the same newly created matrix. Then if AMG_Level::setA() gets called the original matrix is deleted, Aorigial is set to NULL and A uses the passed matrix. In the destructor the matrix is only deleted if Aoriginal and A are the same, i.e. if AMG_Level::setA() was never called.
So this is an ownership management mechanism: only the matrix created in the constructor gets deleted, AMG_Level does not take the ownership of matrices passed through AMG_Level::setA().
This mechanism works, but it is rather confusing and likely to break if a new developer tries to edit the code (my first thought was that it is a dead code which can be removed).
Smart pointers would be a much better option, but that would require an API change.

Start by reading the AMG_Level constructor, setA(), and destructor to trace the ownership behavior described in the issue. Decide and document the intended ownership model and API impact; the work is done when the confusing Aoriginal behavior is replaced or clearly resolved without ambiguity.