qr decomposition

Discussion in 'Undergraduate Math' started by DitzaN, Feb 8, 2011.

  1. DitzaN

    DitzaN Guest

    Hi,

    I was using matlab 7.4(R2007a)
    Now I am using matlab7.11 (R2007b)
    I compared the results of qr function
    the input was
    -0.002567107834001 0.000011594153560 -0.001071830879080
    -0.000348397823395 0.002671433293894 0.000451336098179
    -0.000000757384596 -0.000000006341647 0.000000956196323
    I didn't got the same answer in the two version
    the difference between the version is
    Q1-Q

    ans =

    0 -0.2690 -0.0000
    0 1.9818 -0.0000
    0 -0.0001 0.0000

    R1-R

    ans =

    0 0 0
    0 0.0053 0.0012
    0 0 0

    if I dividing them I got
    Q1./Q

    ans =

    1.0000 -1.0000 1.0000
    1.0000 -1.0000 1.0000
    1.0000 -1.0000 1.0000

    R1./R

    ans =

    1.0000 1.0000 1.0000
    NaN -1.0000 -1.0000
    NaN NaN 1.0000

    why is this differences?
    Is this decomposition is not unique?
    Is there is way to get from 7.11 the same results as 7.4?

    Thanks,
    Ditza
     
    DitzaN, Feb 8, 2011
    #1
    1. Advertisements

  2. Hi,
    You'd better try the comp.soft-sys.matlab forum
    for your question.

    Best wishes
    Torsten.
     
    Torsten Hennig, Feb 8, 2011
    #2
    1. Advertisements

  3. DitzaN

    DitzaN Guest

    oops!

    I meant to post thier
     
    DitzaN, Feb 8, 2011
    #3
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.