Finding values in a matrix with logical operation

Hi

I know how to show for a Matrix A the values in the first column which fullfill a certain condition. Say:

A =

       8     1     6
       3     5     7
       4     9     2

Then I could use for displaying all the values bigger then 3 in the first column the following line:

A(A(:,1) > 3)

But what line do I use, if I want to display the values in the second column which are bigger than say "3"?

Thanks

[Matt J]

Then I could use for displaying all the values bigger then 3 in the first column the following line: A(A(:,1) > 3)

While this would work in the case of the first column, it is cleaner to specify the column number explicitly not just in the indexing expression, but also in the look-up expression

A(A(:,1) > 3, 1 )

It's also easier to see how to generalize it to other columns, as Jan has showed you.

Answer 1

[Jan]

A strange question. What about replacing the column index 1 by 2?

A(A(:, 2) > 3, 2)

Explicitly:

v = A(:, 2);
v(v > 3)

[MiauMiau]

sorry for the strange question. I was not aware that it is possible to use booleans in that way, since A(:,2) > 3 in our case returns a boolean 3,1-Matrix, whereas the index for the column is just the 1,1 matrix "2". That's not so obvious to come up with for a beginner.