title: Three-dimensional array as a vector of arrays
body: <p>I have 3-dim double array with two of its dimensions known at compile time.
  So to make it efficient, I'd like to write something like</p>
  
  <pre><code>std::vector&lt;double[7][19]&gt; v;
  v.resize(3);
  v[2][6][18] = 2 * 7*19 + 6 * 19 + 18;
  </code></pre>
  
  <p>It's perfect except it does not compile because of "v.resize(3);"
  Please don't recommend me using nested vectors like</p>
  
  <pre><code>std::vector&lt;std::vector&lt;std::vector&lt;double&gt;&gt;&gt; v;
  </code></pre>
  
  <p>because I don't want to set sizes for known dimensions each time I extend v by its first dimension.</p>
  
  <p>What is the cleanest solution here?</p>