Modifying the elements of a matrix using a condition

My matrix is Y=[1 2 5 0; 3 4 0 0; 7 0 3 0; 0 0 0 1]

I want to replace zeros '0' with '0.001'

How can I do it basically?

Thanks a lot!

Answer 1

[Guillaume]

As long as 0 is exactly 0 (and not some very small value that's close to zero):

Y(Y==0) = 0.001;

Probably better would be, if all Y>=0

Y(Y<0.001) = 0.001;

[Rengin]

Could you also provide the loops for columns and rows, please?

[Guillaume]

I don't understand what you're asking now. My answer will work whatever the shape and number of dimensions of Y.