Say I have a 1000x10 matrix. The top of the matrix contains noisy data that I want to cut out. From column one I'd like to remove 10 values, from column 2, 15 values, from column 3, 8 values etc. After each column is reduced, I will keep the next 500 entries. So the end matrix will be 500x10. Right now I am doing it one column at a time which I have to put back together. Very tedious.