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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] QR factorization question
- From: Benoit Jacob <jacob.benoit.1@xxxxxxxxx>
- Date: Sat, 29 Aug 2009 11:15:15 -0400
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2009/8/27 Jitse Niesen <jitse@xxxxxxxxxxxxxxxxx>:
> On Wed, 26 Aug 2009, Eric Chu wrote:
>
>> great! that solved my problem.
>> i have another issue though: A is a skinny matrix (m > n), and the matrix
>> Q
>> is square (m x m).
>>
>> how do i retrieve the appropriate Q matrix that goes with my (now) upper
>> triangular R? (i.e. A = [Q1 Q2] [R1; 0]--or the "economy size
>> decomposition"
>> in Matlab)
>
> To get "economy size decomposition", you just have to select the right
> submatrices.
Thanks for the explanation, that was helpful to me too :)
We still want to offer an API for that as it's really inefficient to
have to construct the whole Q matrix only to take a block in it. Will
think about that...
Benoit