title: lambda expression error: expression must be a modifiable lvalue
body: <p>Ok, the codes are:</p>
  
  <pre><code>vector&lt;vector&lt;double&gt;&gt; imageFiltered;
  
  // some processing codes here
  
  parallel_for( blocked_range&lt;unsigned&gt;(0, imageFiltered.size()),
      [=](const blocked_range&lt;unsigned&gt;&amp; r) {
          for( unsigned i = r.begin(); i != r.end(); ++i ){
              for( unsigned j = 0; j != imageFiltered[i].size(); ++j ) {
                  imageFiltered[i][j] = 0; // error here：expression must be a modifiable lvalue
              }
          }
  });
  </code></pre>
  
  <p>And I've write another similar code block which works just fine. So, a little help here.
  PS: parallel_for is from Interl TBB.</p>