Hi all,
  I'm new with ublas and I also consider that lack of operator* for matrix-matrix is a real turn-off for newbies, specialy when reading the compilator errors.
This can be issued by appropriate use of boost::disable_if .
The problem comes from the two operator *
scalar * matrix
matrix * scalar
that are both defined for
matrix_expression * matrix_expression
Also they are badly defined for this case.
But if you disabled them by changing the returned type to

typename boost::disable_if<boost::is_base_of<matrix_expression<T1>,T1>,                                      typename matrix_binary_scalar1_traits<const T1, E2, scalar_multiplies<T1, typename E2::value_type> >::result_type     >::type                                                                                                                                                                                  
and

typename boost::disable_if<boost::is_base_of<matrix_expression<T2>,T2>,                                      typename matrix_binary_scalar2_traits<E1, const T2, scalar_multiplies<typename E1::value_type, T2> >::result_type        >::type

one can now add a matrix-matrix operator*

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                                                                                                                     
    operator* (const matrix_expression<E1> &e1,                                                                  const matrix_expression<E2> &e2) { 
return prod(e1,e2);
    }

Of course there is many other operator* to define for matrix-vector, etc cases and scalar operator * must also be disabled for vector_expression.

I join a minimalist test program and my modified version of operator* (only matrix-matrix case) to this post.

I really think matrix-matrix operator * should be implemented.

Patrick Lacasse

2009/2/12 Jesse Perla <jesseperla@gmail.com>

And one more question on ublas itself:  I have seen a lot of people ask this, but I got a lot of flack for the lack of the * overloading for matrix-matrix and matrix-vector from the matlab programmers.  Could these be added without too much difficulty? 

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