[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: no way for simple matrix lookup ?
From: |
Jonathan C. Webster |
Subject: |
Re: no way for simple matrix lookup ? |
Date: |
Wed, 16 Jun 2004 17:16:41 -0400 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 |
D. Goel wrote:
Hi
[1] Suppose A is a nxn matrix. And b and c are vectors. How do i
return elements of A specified by b and c?
i.e. Want to return a vector D, such that
D(i) = A(b(i), c(i))
Ravel the matrix A out into one long vector, A_vec, using fortran indexing if
you want.
Then combine vec_b and vec_c into a single index vector into your A_vec.
.
vec_3 = vec_b + size(A)(1) * (vec_c - 1)
Finally, your new reordered result vector D_vec
D_vec = A_vec(vec_3)
I think thats right, but check it. Think carefully about which should be vec_b
and vec_c.
Jonathan Webster
-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.
Octave's home on the web: http://www.octave.org
How to fund new projects: http://www.octave.org/funding.html
Subscription information: http://www.octave.org/archive.html
-------------------------------------------------------------
- no way for simple matrix lookup ?, D. Goel, 2004/06/16
- Re: no way for simple matrix lookup ?, Mike Miller, 2004/06/16
- Re: no way for simple matrix lookup ?, D. Goel, 2004/06/16
- Re: no way for simple matrix lookup ?, Mike Miller, 2004/06/16
- Re: no way for simple matrix lookup ?, Quentin Spencer, 2004/06/16
- Re: no way for simple matrix lookup ?, Julius Smith, 2004/06/18
- Re: no way for simple matrix lookup ?, Julius Smith, 2004/06/18
- Re: no way for simple matrix lookup ?, Mike Miller, 2004/06/18
- Re: no way for simple matrix lookup ?, Julius Smith, 2004/06/18
Re: no way for simple matrix lookup ?, Etienne Grossmann, 2004/06/16
Re: no way for simple matrix lookup ?,
Jonathan C. Webster <=