title: I need to choose a sub-matrix from a matrix with minimal difference with unitary results
body: <p>In matlab, I have a matrix X with size e.g.,  12 x 17,   I need to select an 12 x 12 sub-matrix  from it Y such that the sum of column and rows of the matrix Y is minimum into the sum of columns and rows of the matrix eye(12), which can be explained in matlab as follows:  <code>sum(sum(abs(Y))) - sum(sum(eye(12)))</code>. I want only to select 12 columns out of 17, it's not necessary to change the rows locations. It means I need only to choose 12 columns from X with my condition.</p>
  <p>I couldn't understand how to start doing that program.</p>