There are lots of QR decomposition algorithms and the results are not
necessarily unique, especially for rank deficient inputs.
If you post your exact results, I could comment more specifically. Without
more details, I really can't answer your question in any specific way.
On Wed, Jan 18, 2012
Hi, Ted
Thanks for your comment. The original matrix is:
qRef - 3 x 3
12.0 -51.0 4.0
6.0 167.0 -68.0
-4.0 24.0 -41.0
The result of mahout:
q - 3 x 3
-0.85714 0.39429 -0.33143
-0.42857 -0.90286 0.03429
0.28571 -0.17143 -0.94286
r - 3
