Hi, I have this line of code in my header file: project(C, range(0, A_rows), range(0, A_cols)) = A; I've specified: #include <boost/numeric/ublas/storage.hpp> using namespace boost::numeric::ublas; at the beginning of the header file When I compile my .cpp file, I get an error message saying: "c:\users\c9995799\desktop\level 1 problem for mpi\dmatrix.hpp(34): error C2784: 'const boost::numeric::ublas::matrix_range<M> boost::numeric::ublas::project(const boost::numeric::ublas::matrix_range<M> &,const matrix_range<M>::range_type &,const matrix_range<M>::range_type &)' : could not deduce template argument for 'const boost::numeric::ublas::matrix_range<M> &' from 'boost::numeric::ublas::matrix<T>'" This error goes away if I substitute boost::numeric::ublas::range instead of just range here: project(C, range(0, A_rows), range(0, A_cols)) = A; How do I get this to work the way it currently is? Thanks, Vimal