title: fastest way to initialize a template 2D std:array to 0
body: <p>I have a templated 2d array <code>std::array&lt; std::array&lt;ScalarType ,3&gt; ,3 &gt; my_array</code> and I want to set them all to zero at different times in the program. It seems like I can use <code>std::array::fill</code> but </p>
  
  <pre><code>my_array.fill(0);
  </code></pre>
  
  <p>Is not working. How do I fill the 2d array properly?</p>