[Boost-users] Question regarding ublas::identity_matrix

Hi all, I'm a newcomer to uBlas. Please consider the following code: identity_matrix<double> matI(3); int row = matI.size1(); int col = matI.size2(); now that matI has the same number of rows and columns, why the identity_matrix template class has two "size" member functions: size1() and size2()? And has two "size" member variables: size1_ and size2_? Why not use just size() and size_?