Hi The following line has compiled and worked corect until I changed to gcc 3.4.2 and boost 1.32. I am working under fedora core 3. ... matrix<double> m(3,3); cout << prod(prod(m,m),m) << std::endl; ... The compiler error is: /opt/include/boost-1_32/boost/numeric/ublas/matrix_expression.hpp: In function `typename boost::numeric::ublas::matrix_matrix_binary_traits<typename E1::value_type, E1, typename E2::value_type, E2>::result_type boost::numeric::ublas::prod(const boost::numeric::ublas::matrix_expression<E>&, const boost::numeric::ublas::matrix_expression<E2>&) [with E1 = boost::numeric::ublas::matrix_matrix_binary<boost::numeric::ublas::matrix<double, boost::numeric::ublas::row_major, boost::numeric::ublas::unbounded_array<double, std::allocator<double> >

, boost::numeric::ublas::matrix<double, boost::numeric::ublas::row_major, boost::numeric::ublas::unbounded_array<double, std::allocator<double> > , boost::numeric::ublas::matrix_matrix_prod<double, double, double> >, E2 = boost::numeric::ublas::matrix<double, boost::numeric::ublas::row_major, boost::numeric::ublas::unbounded_array<double, std::allocator<double> > >]': /home/jbouecke/FLAVOR/mainprogs/testLinAlg/Test.cc:26: instantiated from here /opt/include/boost-1_32/boost/numeric/ublas/matrix_expression.hpp:5103: error: incomplete type `boost::STATIC_ASSERTION_FAILURE< false>' used in nested name specifier /opt/include/boost-1_32/boost/numeric/ublas/matrix_expression.hpp:5103: error: size of array has non-integral type `<type error>'

I hope someone can help me Thanks Jan Bouecke