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QR factorization
From: |
Marco Caliari |
Subject: |
QR factorization |
Date: |
Fri, 28 Mar 2008 20:10:12 +0100 (CET) |
Hi all.
If you try the following with Octave 3.0.0+
octave:1> A=ones(3,4);
octave:2> [Q,R]=qr(A);
you get
octave:3> Q
Q =
-0.57735 0.81650 0.00000
-0.57735 -0.40825 -0.70711
-0.57735 -0.40825 0.70711
With the other program, you get
Q =
-0.5774 -0.5774 -0.5774
-0.5774 0.7887 -0.2113
-0.5774 -0.2113 0.7887
and the same R. Both the factorizations satisfy Q*R=A and Q'*Q=eye(3) and
both the programs claim to use the LAPACK routines DGEQRF and DORGQR.
Where could be the difference?
Best regards,
Marco
- QR factorization,
Marco Caliari <=