# Change the sign of a particular element in a matrix

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Pranjal Pathak el 28 de Dic. de 2012
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!
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Muruganandham Subramanian el 28 de Dic. de 2012
Editada: Jan el 28 de Dic. de 2012
find(A==-1)=1
[EDITED, Jan, copied from comments] Better: A(A==-1)=1;
or
A=abs(A)
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Muruganandham Subramanian el 28 de Dic. de 2012
Sorry..Azzi Its
A(A==-1)=1;
Pranjal Pathak el 9 de En. de 2013
Thanks for the answer,it worked out!

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### Más respuestas (1)

Image Analyst el 28 de Dic. de 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
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Shaun VanWeelden el 28 de Dic. de 2012
Jan el 28 de Dic. de 2012
@Shaun: You can vote this answer, if you find it useful.

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