title: Summing block vector of matrices in MATLAB
body: <p>Let <code>A</code> be a <code>(m x j*m)</code> matrix, <code>A1=A(1:m,1:m)</code> and <code>A2=A(1:m,(m+1):2*m)</code>, and so on.  </p>
  
  <p>What would some easy code be to compute <code>A1+...+Aj</code> for some integer <code>j&gt;1</code>. </p>
  
  <p>Thanks</p>