One such example is a text retrieval engine. A x is easy since that is what the engine does. A' y is very expensive.
2012/1/12 Sébastien Brisard <sebastien.bris...@m4x.org> > In other words, I do not know how to access > efficiently the (i, j) coefficient, but I *do* know how to compute > efficiently A.x. There might be some cases where computing A'.x would > still be difficult. I do not have an example here, but that's the > reason why initially > RealVector operateTranspose(RealVector) > was not put in the RealLinearOperator abstract class. >
