Re: [eigen] Error: trying to recover Q matrix in sparse QR factorization

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On 07.05.2013 05:03, Avneesh Saluja wrote:

I have a question regarding the sparse QR implementation in the latest
development build of Eigen.

I would like to recover the Q matrix after the factorization, but can't
quite do so.  I have followed the suggestion in the following link to get
the SparseMatrix representation of Q (where I assume A is the original
matrix that we are taking the factorization of):

That looks mostly like a documentation issue. In general, it does not make sense to store Q as a sparse matrix, since usually it is not anything near sparse. You can directly use qr_factorizer.matrixQ() inside expressions. If you really need the actual Q, I guess the simplest way would be to multiply by an identity matrix.


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