Hello, Here is the problem I am having: In the following code (tried to keep it as short as possible), I create a vector [vec1] and a matrix [mat1] in the respective test functions. Then, I create [vec2] and [mat2] in main, but when I print them they have the values of [vec1] and [mat1]. Why is this happening? I am quite new to boost, so I may miss something quite fundamental. I really appreciate you help. System: Fedora Core 4, boost-1.33.1.-5, g++ 4.0.2 Regards, Vasilios ---------------------------------------------------------------------------------------------------------------------------------------------------------- #include <boost/numeric/ublas/vector.hpp> #include <boost/numeric/ublas/matrix.hpp> #include <boost/numeric/ublas/io.hpp> typedef boost::numeric::ublas::matrix<double> ublas_matrix; typedef boost::numeric::ublas::vector<double> ublas_vector; using std::cout; using std::endl; void test_matrix(); void test_vector(); int main() { test_matrix(); ublas_matrix mat2(3, 2); cout << "m2 = " << mat2 << endl; test_vector(); ublas_vector vec2(4); cout << "v2 = " << vec2 << endl; } void test_matrix() { unsigned m = 3, n = 2; ublas_matrix mat1(m, n); for (unsigned i = 0; i < m; ++ i) for (unsigned j = 0; j < n; ++ j) mat1(i, j) = 5.0; } void test_vector() { ublas_vector vec1(4); for (unsigned i = 0; i < vec1.size(); ++i) vec1(i) = i; } ----------------------------------------------------------------------------------------------------------------------------------------------------------