Re: [ublas] uBlas matrix * matrix operation

From: Brian Budge (brian.budge_at_[hidden])
Date: 2006-07-27 11:48:42

Someone correct me if I'm wrong, but I think the uBlas matrices are
not meant to be used with operator*.  There is a prod function...

On 7/27/06, Dave Steffen <dgsteffen_at_[hidden]> wrote:
>
>
> Hi Folks,
>
> This is my first excursion into uBlas.  I'm getting an "ambiguous
> overload for 'operator*' in 'a * b' " sort of error out of this:
>
> #include <boost/numeric/ublas/vector.hpp>
> #include <boost/numeric/ublas/matrix.hpp>
> #include <boost/numeric/ublas/matrix_expression.hpp>
> namespace UB
> {
>     using namespace boost::numeric::ublas;
>
>     template <int N>  struct Type
>     {
>         typedef matrix<double, row_major, bounded_array<double, N*N> > matrix;
>     };
> }
>
> // elsewhere...
>
>    typename UB::Type<N>::matrix a(N,N), b(N,N);
>
>     for (int i = 0; i < N; ++i)
>         for (int j = 0; j < N; ++j)
>             {
>                 a(i,j) = 1.0 / (i + j+1);
>                 b(i,j) = 1.0 / (i + j+1);
>             }
>
>     a * b;
>
> The error (from GCC 3.4.6) is this ugly thing:
>
> /usr/local/home/dgsteffen/local/GCC34/Boost/1_32/boost/numeric/ublas/matrix_expression.hpp:3632:
> note: candidates are: typename boost::numeric::ublas::matrix_binary_scalar2_traits<E1, const
> T2, boost::numeric::ublas::scalar_multiplies<typename E1::value_type, T2>,
> boost::numeric::ublas::scalar_reference<const T2> >::result_type
> boost::numeric::ublas::operator*(const boost::numeric::ublas::matrix_expression<E>&, const
> T2&) [with E1 = boost::numeric::ublas::matrix<double, boost::numeric::ublas::row_major,
> boost::numeric::ublas::bounded_array<double, 441u, std::allocator<double> > >, T2 =
> boost::numeric::ublas::matrix<double, boost::numeric::ublas::row_major,
> boost::numeric::ublas::bounded_array<double, 441u, std::allocator<double> >
> >]
> /usr/local/home/dgsteffen/local/GCC34/Boost/1_32/boost/numeric/ublas/matrix_expression.hpp:3162:
> note:                 typename boost::numeric::ublas::matrix_binary_scalar1_traits<const T1, E2,
> boost::numeric::ublas::scalar_multiplies<T1, typename E2::value_type>,
> boost::numeric::ublas::scalar_reference<const T1> >::result_type
> boost::numeric::ublas::operator*(const T1&, const
> boost::numeric::ublas::matrix_expression<E2>&) [with T1 =
> boost::numeric::ublas::matrix<double, boost::numeric::ublas::row_major,
> boost::numeric::ublas::bounded_array<double, 441u, std::allocator<double> > >, E2 =
> boost::numeric::ublas::matrix<double, boost::numeric::ublas::row_major,
> boost::numeric::ublas::bounded_array<double, 441u, std::allocator<double> > >]
>
> Any thoughts on what I'm doing wrong?
>
> Thanks!
>
> ----------------------------------------------------------------------
> Dave Steffen, Ph.D.
> Software Engineer IV              Disobey this command!
> Numerica Corporation
> ph [phone] x27
> fax [phone]                   - Douglas Hofstadter
> dgsteffen_at_[hidden]
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