Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

RQ decomposition from QR decomposition

  1. Oct 5, 2008 #1
    What I'm wondering is:

    Q and R in the QR decomposition of A are the same Q and R in the RQ decomposition of which matrix?

    I found some matlab code which will get RQ from QR, but I don't understand how you would do those operations FIRST, then find the QR decomposition.

    Code (Text):
    ReverseRows = [0 0 1; 0 1 0 ; 1 0 0];
    [Q R] = qr((ReverseRows * A)');
    R = ReverseRows * R' * ReverseRows;
    Q = ReverseRows * Q';
    Any tips about the intuition of the relations of these factorizations?

  2. jcsd
  3. Oct 5, 2008 #2
    I guess what I was looking for is that QR is Gram-Schmidt applied to the column of A, where RQ is Gram-Schmidt applied to the rows of A.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook