title: Boost library simple compilation with tuples
body: <p>Can anyone tell me why this works (compiles and runs)</p>
  
  <pre><code>#include &lt;iostream&gt;
  #include &lt;boost/numeric/ublas/matrix.hpp&gt;
  //#include &lt;boost/tuple.hpp&gt;
  //#include &lt;boost/tuple_comparison.hpp&gt;
  //#include &lt;boost/tuple_io.hpp&gt;
  using namespace boost;
  
  int main ( )
  {
  //  tuple&lt;int, char, float&gt; t(2, 'a', 0.9);
  //  std::cout &lt;&lt; t &lt;&lt; std::endl;
      boost::numeric::ublas::matrix&lt;double&gt; m1;
       return 0;
   }
  </code></pre>
  
  <p>but when I uncomment the lines related to tuple, it says</p>
  
  <blockquote>
    <p>boost_tuple.cpp:3:27: fatal error: boost/tuple.hpp: No such file or directory
    compilation terminated.</p>
  </blockquote>
  
  <p>I use the following to compile in both cases:</p>
  
  <blockquote>
    <p>g++ -Wall -c -I/usr/include/boost boost_tuple.cpp</p>
  </blockquote>
  
  <p>And I also checked that <code>/usr/include/boost/tuple.hpp</code> exists </p>