title: Reorder columns in a matrix
body: <p>Suppose that I have an <code>n</code> row, <code>m</code> column matrix <code>A</code>, and I want to reorder every column in <code>m</code> according to the sorting of some specific row.</p>
  
  <p>For instance, if I take <code>order(A[,k])</code>, that gives me the numeric or alphabetical order of elements in column <code>k</code>. I now want to sort every column in matrix <code>A</code> according to those rankings, so that elements <code>1...n</code> in every row are ordered to correspond to elements <code>1...n</code> (by rank) in column <code>k</code>. Is there a simple way to do this without looping over all columns?</p>