hpp> includes <iostream>. I remember that it is better not to include <iostream> but something like <ostream> and <istream>, or even simply <iosfwd>.

I'm wondering if this issue shall be corrected in the future version of ublas.

Thanks,
Peng

#include <boost/numeric/ublas/matrix.hpp>

int main () {
  std::cout << "Hello" << std::endl;
}