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matrix subsetting
From: 
John W. Eaton 
Subject: 
matrix subsetting 
Date: 
Fri, 31 Mar 2000 02:54:54 0600 (CST) 
On 30Mar2000, Heber Farnsworth <address@hidden> wrote:
 How does one do matrix subsetting in a dynamically loaded function (.oct
 file)? I know how to put a whole matrix into a certain place in a
 larger matrix using insert but I don't know how to do the reverse. I
 want to create a matrix out of part of an existing matrix. In an mfile
 you would write

 Y = X(a:b,c:d);

 Does anyone know how to do this?
Yes, but exactly how depends on what kinds of objects X, a, b, c, and
d are. If you have X as a Matrix object, and a, b, c, d are ints, you
can use
Matrix Matrix::extract (int r1, int c1, int r2, int c2) const;
(you'll need to adjust for the fact that Matrix objects use a 0based
indexing).
jwe

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