[eigen] Converting code SparseQR -> SuiteSparse SPQR

[Stéphane Mottelet <stephane.mottelet@xxxxxx>]

Hello,

I have a code using regular SparseQR working fine (within a Scilab gateway):

    typedef Eigen::SparseMatrix<double, 0x1, int> RealSparse_t;

    types::Sparse *pSpA = in[0]->getAs<types::Sparse>();
    types::Sparse::RealSparse_t* sp0 = pSpA->matrixReal;

    Eigen::SparseQR <types::Sparse::RealSparse_t, 
Eigen::COLAMDOrdering<int> > qr;
    qr.compute(*sp0);

    pOutR = new types::Sparse(new 
types::Sparse::RealSparse_t(qr.matrixR()),NULL);
    out.push_back(pOutR);

    Eigen::SparseMatrix<double> Q;
    Q = qr.matrixQ();
    pOutQ = new types::Sparse(new types::Sparse::RealSparse_t(Q),NULL);
    out.push_back(pOutQ);

I wanted to test SuiteSparse SPQR instead, but the mechanism to recover 
the Householdr reflection list qr.matrixQ() as a regular matrix does not 
seem to be supported, as the almost same as above following code 
(Eigen::SparseQR is replaced by Eigen::SPQR and header include (not 
shown here) is also updated)

    typedef Eigen::SparseMatrix<double, 0x1, int> RealSparse_t;

    types::Sparse *pSpA = in[0]->getAs<types::Sparse>();
    types::Sparse::RealSparse_t* sp0 = pSpA->matrixReal;

    Eigen::SPQR <types::Sparse::RealSparse_t> qr;
    qr.compute(*sp0);

    pOutR = new types::Sparse(new 
types::Sparse::RealSparse_t(qr.matrixR()),NULL);
    out.push_back(pOutR);

    Eigen::SparseMatrix<double> Q;
    Q = qr.matrixQ();
    pOutQ = new types::Sparse(new types::Sparse::RealSparse_t(Q),NULL);
    out.push_back(pOutQ);

does not compile and yields the following error (SPQR updated code 
compiles and runs fine when extracting R only):

error: no viable overloaded '='

 Q = qr.matrixQ();

How can I recover the Q matrix when using SuiteSparse SPQR ?

Thanks for your help.

--
Stéphane Mottelet
Ingénieur de recherche HDR
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
http://www.utc.fr/~mottelet