how to turn elements in matrix to 0?

i have this matrix:

arround this shape the elements are close to zero (in a small values for example: xe-20-xe-10) is there a simple way to take the elements only around this shape and change them into zero?

[Kobi]

i tried to do this in this way but i don't understand what is wrong

[col,row]=find(abs(diag(T))<0.2); T(row,col)=0;

i'm expecting to zero only a square around the shape in this way

Answer 1

[Chad Greene]

If you'd like to change all values in T that are less than some threshold (we'll call the threshold thresh), all you need is

T(T<thresh)=0;

[Kobi]

not for all the values only for a square of zeros i managed to do this in a way that i don't really like i create a threshold for the diognal values of the matrix and take 10% from the scale

treshold=(max(max(abs(diag(T))))-min(min(abs(diag(T)))))*0.1; ind=find(abs(diag(T))<treshold);

but i don't like this because i need to set the threshold manually

any suggestions?

[José-Luis]

Well, a threshold is subjective, even when applying complex statistical methods. You are going to have to select something. Even if you use a function, the choice is subjective.

I guess what I am trying to ask is how do you want to set that limit?

Answer 2

[Chad Greene]

If it's a matter of numerical noise eps may help.