|
|
Ublas : |
Subject: Re: [ublas] Misc implementation issues
From: Ernest Turro (ernest.turro_at_[hidden])
Date: 2009-03-02 10:42:02
On 2 Mar 2009, at 15:11, Ernest Turro wrote:
> Hello,
>
> I've just started using ublas and have encountered several issues. I
> was wondering if anyone would care to comment.
>
> (1) resize() for compressed matrices with data preservation appears
> not to be yet implemented. Instead, I'm creating a copy, resizing
> without data preservation and then copying elements back:
> compressed_matrix<bool> temp(M); // make copy of M
> M.resize(m,n,false); // resize without data preservation
> for(boolMatIt1 i1 = temp.begin1(); i1 != temp.end1(); ++i1) {
> for (boolMatIt2 i2 = i1.begin(); i2 != i1.end(); ++i2) {
> M(i2.index1(),i2.index2())= *i2;
> }
> }
> Is someone working on finishing implementing resize()? Is the above
> an efficient workaround for now?
>
>
> (2) Multiplying a compressed matrix of ints times a vector of ints
> and returning a vector of ints gives a runtime error (yet
> multiplying times a vector of doubles and returning a vector of
> doubles is fine). E.g. the following gives a runtime error:
> #include <boost/numeric/ublas/matrix_sparse.hpp>
> #include <boost/numeric/ublas/matrix_proxy.hpp>
> using namespace boost::numeric::ublas;
> typedef compressed_matrix<int> intMat;
> int main() {
> intMat M(10,12);
> const vector<int> ones(12,1);
> vector<int> matches = prod(M, ones);
> return 0;
> }
> /* runtime error:
> Check failed in file /opt/local/include/boost/numeric/ublas/detail/
> vector_assign.hpp at line 370:
> detail::expression_type_check (v, cv)
> terminate called after throwing an instance of
> 'boost::numeric::ublas::external_logic'
> what(): external logic or bad condition of inputs
> Abort trap
> */
>
>
> (3) The axpy_prod(mat&, vec1&, vec2&) function seems to require that
> mat is a square matrix but surely it should only require that
> mat.size2() ==vec1.size()==vec2.size(). E.g. the following gives a
> runtime error because M has dimension 10x12 (it works fine if
> dimension is 12x12):
>
> #include <boost/numeric/ublas/matrix_sparse.hpp>
> #include <boost/numeric/ublas/matrix_proxy.hpp>
> #include <boost/numeric/ublas/operation.hpp>
> using namespace boost::numeric::ublas;
> typedef compressed_matrix<double> intMat;
> int main() {
> intMat M(10,12);
> const vector<double> ones(12,1);
> vector<double> matches(12);
> axpy_prod(M, ones, matches);
> return 0;
> }
> /* runtime error:
> Check failed in file /opt/local/include/boost/numeric/ublas/detail/
> vector_assign.hpp at line 349:
> v.size () == e ().size ()
> terminate called after throwing an instance of
> 'boost::numeric::ublas::bad_size'
> what(): bad size
> Abort trap
> */
Apologies, please ignore point (3) above: the runtime error refers to
an incorrect size for the result vector, not a requirement for a
square M.
>
>
> -Ernest
>
> _______________________________________________
> ublas mailing list
> ublas_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/ublas