Change the sign of a particular element in a matrix

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Hi, I have a problem in the following matrix: A=[ -1 1 0 0 0 0; 0 -1 1 0 0 0 ; 0 0 -1 1 0 0; 0 0 0 0 -1 1 ; 0 0 0 0 0 -1 ; 0 0 0 0 0 0];
In the above matrix, I need to change only the element -1 by +1, while others remaining the same. For, small matrix, it is possible by defining the row and column elements but for large matrix, is there any way of doing it programatically in matlab as the dimension of the matrix may be larger than this. Please help me in this regard.
Thanking You!

Accepted Answer

Muruganandham Subramanian
Muruganandham Subramanian on 28 Dec 2012
Edited: Jan on 28 Dec 2012
find(A==-1)=1
[EDITED, Jan, copied from comments] Better: A(A==-1)=1;
or
A=abs(A)

More Answers (1)

Image Analyst
Image Analyst on 28 Dec 2012
What do you mean change it by +1? Do you mean change it TO +1, or change it by +1 by adding +1 to the -1 so that you get 0? Here's three different ways to do the two possible meanings of your question:
A = [ -1 1 0 0 0 0; 0 -1 1 0 0 0 ; 0 0 -1 1 0 0; 0 0 0 0 -1 1 ; 0 0 0 0 0 -1 ; 0 0 0 0 0 0]
A(A == -1) = 1
A = [ -1 1 0 0 0 0; 0 -1 1 0 0 0 ; 0 0 -1 1 0 0; 0 0 0 0 -1 1 ; 0 0 0 0 0 -1 ; 0 0 0 0 0 0]
A(A == -1) = 0
A = [ -1 1 0 0 0 0; 0 -1 1 0 0 0 ; 0 0 -1 1 0 0; 0 0 0 0 -1 1 ; 0 0 0 0 0 -1 ; 0 0 0 0 0 0]
elementsToChange = A == -1;
A(elementsToChange) = A(elementsToChange) + 1
  2 Comments
Jan
Jan on 28 Dec 2012
@Shaun: You can vote this answer, if you find it useful.

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