Find all values within a given tolerance of 0

I have a matrix, called "difference". "difference" is 139x101. I would like to output the column numbers (i.e. somewhere between column 1 and column 101), where a value exists (out of the 139) that is within say 0.01% of 0. Is there a way to do this? It would be great if it could output the actual value, and column index. Note that if more than 1 column meets criterion, I want to output both.

[Guillaume]

What is 0.01% of 0, if not 0?

You say you want the column numbers and say that if more than 1 column meets criterion. I assume you mean row for the 2nd part.

[Stephan]

How much is 0.01% from 0 in your case? In the real world it is zero, but i think community knows what you mean. But you need to give a value to calculate 0.01%.

[Benjamin]

Sorry the percentage tolerance does not really make sense. I met within a tolerance on the y-axis (not a percentage, but a finite value distance from 0).

I think this seems to work:

C = difference < 0.0001 & difference > -0.0001;

k = find(C);
l= k/density_ids;

Answer 1

[Guillaume]

Ignoring the 0.01% of 0 and assuming you want the location of elements whose absolute value is less than 0.01, simply:

 [row, column] = find(abs(difference) < 0.01)

To get the corresponding values:

values = difference(sub2ind(size(difference), row, column));

[Benjamin]

works perfectly, thanks!