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Re: FW: Matrix index, Please e-mail back.

From: Jordi Gutierrez Hermoso
Subject: Re: FW: Matrix index, Please e-mail back.
Date: Tue, 5 Dec 2006 17:00:55 -0600

Argh... No offense, and I normally try to be tolerant about top-posters
and HTML emails, but this time I honestly have a hard time understand
who said what and what's going on with this email thread. Ever heard
of trim-posting? To be fair, not many people are even aware that a
different posting style exists:

Anyways, after a while of reading this thread, I think I understand
what's going on. More trim-posted below:

[huge snip]
On  5-Dec-2006, Jorgen Andersson wrote:
| I want to index with [2,3,4] and then [3,4,5] ... [4,5,6] by letting
| i index the index range matrix. Can you do it with octave.
| My octave script works if in a loop. The loop is some slow
| so that is why I would like to use an index to the index ranges.
[more snipped]

I don't understand what you think the bug is, but jwe seemed
unimpressed with your bug report.

At any rate, it sounds you want to get the diagonal of a matrix plus
the super- and subdiagonal. This is easy to do:

   octave:2> A = [1 2 3 4; 5 6 7 8; 9 10 11 12; 13 14 15 16]
   A =

      1   2   3   4
      5   6   7   8
      9  10  11  12
     13  14  15  16

   octave:3> diag(A)
   ans =


   octave:4> diag(A,1)
   ans =


   octave:5> diag(A,-1)
   ans =


If I misunderstood, then please rephrase your question or reformat the
email thread. Sorry to be so pedantic about this. ;-)

- Jordi G. H.

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