I'm a new ublas user, so please bear with me. I'm having trouble with ensuring constness of the resource a matrix proxy provides access to. As I understand it, constness of the proxy propagates to constness of the resource through pairs of const / non-const members, but I think this is not secure enough. So I declared a matrix_indirect<const matrix<...> >. The problem is, how do I convert a matrix_proxy to a mutable matrix (ie. matrix_indirect<matrix<...>, ...>) to a non-mutable matrix (matrix_indirect<const matrix<...>, ...>). I hope this question is not very stupid.