Hi list. I got a problem of matrix initialization. Please see the following code: #include <iostream> #include <iterator> #include <boost/numeric/ublas/matrix.hpp> #include <boost/numeric/ublas/io.hpp> using namespace std; using namespace boost::numeric::ublas; int main () { matrix<double> m(3, 3); for (unsigned i = 0; i < 3; i++) m(i, i) = -i; cout << m << endl; return EXIT_SUCCESS; } In this code, I'm trying to initialize the diagonal with -1, -2, -3. But, the result is obviously different from what I expected: [3,3]((0,0,0),(0,4.29497e+09,0),(0,0,4.29497e+09)) This must be due to type conversion from unsigned from double that occurs at 'm(i, i) = -i'. IMHO, the code must works as follows i // unsigned -i // (-1) * i = int * unsigned = int m(i, i) = -i // lhs is double, so int on rhs should be converted // into double. But the result implies that I'm wrong. Anybody knows what I'm missing here? How would you correct the above code? Sincerely, Minkoo Seo