Manipulation of certain matrix elements which meet a certain criterion

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Praneeth Lanka
Praneeth Lanka on 30 Aug 2021
Commented: KALYAN ACHARJYA on 30 Aug 2021
Let's say I have a matrix of size 100X100. I wish to manipulate certain elements of the Matrix which are in Rows 10 to 15 and coulmns 11 to 13, which are negative numbers. I donot wish to change the elements which are negative outside the specified Rows and Columns.
Is it possible to do this without creating any new variable ? by using Logical Indexing?
Edit: I have generalized the question, but here is where I intend to implement the solution provided. I have a 15X16 matrix in which there are NaN values in random positions of the matrix. I would like to set these NaN values to 0s' in only the sub-matrix formed by Rows 2 to 15 and Columns 2 to 16. So in this case I would be required to use the isnan function.

Answers (1)

KALYAN ACHARJYA on 30 Aug 2021
mat=randi([-5,5],[100,100]); % Sample Matrix
[r,c]=find(mat(10:15,11:13)<0==1); % Get the indices
mat(9+r,10+c)=x; % x Manupulate any Value
Please note there may be more easier solution.
KALYAN ACHARJYA on 30 Aug 2021
Yes you can get that ...
But during manipulation, you may have to use groups of rows & columns number.

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