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Subject: [ublas] I have a problem with expression templates
From: George Slavov (gpslavov_at_[hidden])
Date: 2012-09-26 13:17:40


I am using MSVC 2010 and trying to compile the following code

ublas::prod(trans(A), ublas::prod(B, A));

where A and B are matrices of the basic type ublas::matrix<double>. So the
product should equal A^T B A. However, I get a compile error on the static
assert line of the following

// Dispatcher
template<class E1, class E2>
BOOST_UBLAS_INLINE
typename matrix_matrix_binary_traits<typename E1::value_type, E1,
      typename E2::value_type, E2>::result_type
prod (const matrix_expression<E1> &e1,
        const matrix_expression<E2> &e2) {
    BOOST_STATIC_ASSERT (E1::complexity == 0 && E2::complexity == 0);
    typedef typename matrix_matrix_binary_traits<typename E1::value_type,
E1,
       typename E2::value_type, E2>::storage_category storage_category;
    typedef typename matrix_matrix_binary_traits<typename E1::value_type,
E1,
       typename E2::value_type, E2>::orientation_category
orientation_category;
    return prod (e1, e2, storage_category (), orientation_category ());
}

If I compute a temporary result, then I get no problems. Like so:

ublas::matrix<double> temp = ublas::prod(B,A);
ublas::prod(trans(A), temp);

I also tried a case where the expression template won't involve transposes
and I got the same problem. What am I doing wrong?

Regards,
George