How Would I create a matrix which contains the first and last m columns of another matrix?

Assume that n>2m

Answer 1

[Benjamin Kraus]

Lets say you have an M-by-N matrix, and you wanted the first K and last K columns:

m = 10;
n = 20;
k = 3;
A = rand(m,n);
Asub = A(:,[1:k (end-k+1):end]);