Here is an example: <quote> This is the Postfix program at host wowbagger.osl.iu.edu. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to <postmaster> If you do so, please include this problem report. You can delete your own text from the attached returned message. The Postfix program <ublas@lists.boost.org>: mail forwarding loop for ublas@lists.boost.org Final-Recipient: rfc822; ublas@lists.boost.org Action: failed Status: 5.0.0 Diagnostic-Code: X-Postfix; mail forwarding loop for ublas@lists.boost.org ---------- Weitergeleitete Nachricht ---------- From: "Maik Beckmann" <beckmann.maik@googlemail.com> To: "ublas mailing list" <ublas@lists.boost.org> Date: Sun, 19 Oct 2008 18:54:39 +0200 Subject: Re: [ublas] When I can not use two prec_prod's? 2008/10/19 Peng Yu <pengyu.ut@gmail.com>:
#include <boost/numeric/ublas/matrix.hpp> #include <boost/numeric/ublas/io.hpp>
int main () { boost::numeric::ublas::matrix<double> m(2, 2);
m(0, 0) = 1; m(1, 0) = 2; m(0, 1) = 3; m(1, 1) = 4;
std::cout << prec_prod(m, prec_prod(m, m)) << std::endl;//error }
Hello Peng, $ g++ test.cpp gives {{{ /usr/include/boost/numeric/ublas/matrix_expression.hpp:4839: error: invalid application of 'sizeof' to incomplete type 'boost::STATIC_ASSERTION_FAILURE<false>' test.cpp:12: instantiated from here }}} where /usr/include/boost/numeric/ublas/matrix_expression.hpp: {{{ 4837_ prec_prod (const matrix_expression<E1> &e1, 4838: const matrix_expression<E2> &e2) { 4839: BOOST_STATIC_ASSERT (E1::complexity == 0 && E2::complexity == 0); ... }}} The problem is the nested prec_cond call. This {{{ #include <boost/numeric/ublas/matrix.hpp> #include <boost/numeric/ublas/io.hpp> int main () { typedef boost::numeric::ublas::matrix<double> mx_type; mx_type m(2, 2); m(0, 0) = 1; m(1, 0) = 2; m(0, 1) = 3; m(1, 1) = 4; std::cout << prec_prod(m, mx_type(prec_prod(m, m))) << std::endl; } }}} works, since mx_type(prec_prod(m, m)) forces the matrix expression returned by prec_prod(m, m) to be evaluated to mx_type, which in turn causes E2::complexity == 0. Regards, -- Maik _______________________________________________ ublas mailing list ublas@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/ublas </quote> But the message has been received: - http://lists.boost.org/MailArchives/ublas/2008/10/3024.php -- Maik