Re: [eigen] combine matrix blocks

[Stefan Ulbrich <s.ulbrich@xxxxxxxxxxxxxx>]

Hello,

thank you for your answer. I managed to fix the error (I had a reference to a temporary variable involved).

I think the MatrixView is a nice feature that I'd like to share with other users or to see in a future Eigen release.

Is there a place - maybe on the wiki - where one can publish his own plugins?

best,

Stefan

Am 27.11.2009 um 00:15vorm. schrieb Gael Guennebaud:

I don't really get it, but it seems you want to add a MatrixBase member returning an IndirectView. Then the correct way to write it is:

template<typename Derived>
class MatrixBase : ......
{
 // ......

  template<typename A, typename B>
  IndirectView<Derived,A,B> view(const A& a, const B& b) { return  IndirectView<Derived,A,B>(derived(), a, b); }

};

Does that help ?

Also in your code you are mixing IndirectView and MatrixView, but I guess that's just a copy paste typo.

gael.

On Thu, Nov 26, 2009 at 6:27 PM, Stefan Ulbrich <s.ulbrich@xxxxxxxxxxxxxx> wrote:

Hello,

sorry for the very long delay, I could not find the time to continue the work on my project with Eigen.

The matrix view/proxy works quite well (addressing of elements via two lists of indices). I only have still one problem. I want to hide the creation of a 

matrixview object within a member:

MatrixView<MatrixXd,Dynamic,Dynamic> getView(){

return m_matrix(range1,range2);

}

But it seems that this does not work .. for instance cout<<getView() 

gives me an exception in malloc.

Do you have any idea what could go wrong? 

Thank you very much!

Best,

Stefan

template<typename MatrixType, typename RowType, typename ColType> class MatrixView

: public MatrixBase<MatrixView<MatrixType, RowType, ColType> >

{

public:

EIGEN_GENERIC_PUBLIC_INTERFACE(IndirectMatrix)

inline IndirectMatrix(const MatrixType& matrix, const RowType &rows, const ColType &cols)

: m_matrix(matrix), m_rows(rows), m_cols(cols)

{

//std::cout << "Debug: " << m_rows.minCoeff() << "," << m_rows.maxCoeff() << "," << matrix.rows() << std::endl;

//std::cout << "Debug: " << m_cols.minCoeff() << "," << m_cols.maxCoeff() << "," << matrix.cols() << std::endl << matrix << std::endl << m_matrix << std::endl;

ei_assert(m_rows.minCoeff() >= 0 && m_rows.maxCoeff() < matrix.rows()

&& m_cols.minCoeff() >= 0 && m_cols.maxCoeff() < matrix.cols());

}

EIGEN_INHERIT_ASSIGNMENT_OPERATORS(IndirectMatrix)

inline int rows() const { return m_rows.rows(); }

inline int cols() const { return m_cols.rows(); }

inline Scalar& coeffRef(int row, int col)

{

return m_matrix.const_cast_derived().coeffRef(m_rows(row), m_cols(col));

}

inline const Scalar coeff(int row, int col) const

{

return m_matrix.coeff(m_rows(row), m_cols(col));

}

protected:

const typename MatrixType::Nested m_matrix;

const typename RowType::Nested m_rows;

const typename ColType::Nested m_cols;

};