title: What guarantees behaviors of operators for slice_array class?
body: <p>In <code>&lt;valarray&gt;</code> header, five class templates are defined: <code>valarray</code>, <code>slice_array</code>, <code>gslice_array</code>, <code>mask_array</code> and <code>indirect_array</code>.</p>
  
  <p>For <code>valarray&lt;Type&gt;</code> objects, any operators influences all the elements. For example, </p>
  
  <pre><code>int array1[] = {1,2,3};
  int array2[] = {4,5,6};
  valarray&lt;int&gt; v1(array1, 3);
  valarray&lt;int&gt; v2(array2, 3);
  valarray&lt;int&gt; v3 = v1 + v2; //v3 has 5, 7 and 9.
  </code></pre>
  
  <p>This is the very reason some users use <code>valarray</code> instead of other containers like <code>vector</code>, and this operator's behavior is described by many reliable websites.</p>
  
  <p>By the way, it is a fact that, also in the rest class templates in <code>&lt;valarray&gt;</code>, the operators are overloaded. However, I haven't found any documents in which the behaviors of the operators are described. At least on my environment, the operators behave the same as those of <code>valarray</code> class template, but I'd like to get some written evidence.</p>
  
  <p>In reading <code>&lt;valarray&gt;</code> header, a sentence <code>#include &lt;bits/slice_array.h&gt;</code> is found. And in the <code>slice_array.h</code> header, I found the definitions of the operators:</p>
  
  <pre><code>  ///  Assign slice elements to corresponding elements of @a v.
    void operator=(const valarray&lt;_Tp&gt;&amp;) const;
    ///  Multiply slice elements by corresponding elements of @a v.
    void operator*=(const valarray&lt;_Tp&gt;&amp;) const;
    ///  Divide slice elements by corresponding elements of @a v.
    void operator/=(const valarray&lt;_Tp&gt;&amp;) const;
    ///  Modulo slice elements by corresponding elements of @a v.
    void operator%=(const valarray&lt;_Tp&gt;&amp;) const;
  </code></pre>
  
  <p>Perhaps these can be a hit, but I don't understand what <code>@a v</code> means. (However , this is just an example, but not an evidence.)</p>
  
  <p>Does anyone have the written evidence?</p>