finding a change in a matrix

Hi,

I have a matrix in which each column is usually constant but sometimes the value changes. Is there a way to figure out where the change occurs without running loops? for example A=[ 1 2 3 4 5; 1 2 3 4 5; 1 2 2 4 5; 1 2 2 4 5]

is it possible to compute that observation A(3,3) has changed?

Answer 1

[Sean de Wolski]

 changes_in_columns =  diff(A,1,1)