title: Error: Expected constructor, destructor, type conversion before '<' token
body: <p>the code is </p>
  
  <pre><code>#include &lt;ctime&gt;
  #include &lt;iostream&gt;
  #include &lt;fstream&gt;
  #include &lt;sstream&gt;
  #include &lt;cstdlib&gt;
  #include &lt;iterator&gt;
  #include &lt;queue&gt;
  #include &lt;algorithm&gt;
  #include &lt;string&gt;
  #include &lt;cassert&gt;
  #include &lt;cmath&gt;
  #include &lt;iomanip&gt;
  #include &lt;new&gt;
  #include &lt;algorithm&gt;
  #include &lt;functional&gt;
  #include &lt;vector&gt;
  
  using namespace std;
  
  using std::vector;
  
      #include &lt;boost/numeric/ublas/matrix.hpp&gt;
      #include &lt;boost/numeric/ublas/io.hpp&gt;
      #include &lt;boost/numeric/ublas/operation.hpp&gt;
  #include &lt;boost/numeric/ublas/vector.hpp&gt;
  
      using namespace boost::numeric::ublas;
  
      boost::numeric::ublas::matrix&lt;double&gt; A_MATRIX(A_MATRIX_ROWS,A_MATRIX_COLUMNS);
      boost::numeric::ublas::matrix&lt;double&gt; Y_MATRIX(A_MATRIX_ROWS,1);
  
  
      vector &lt;double&gt; GPSR_BB(boost::numeric::ublas::matrix&lt;double&gt; &amp;f_Y_MATRIX,boost::numeric::ublas::matrix&lt;double&gt; &amp;f_A_MATRIX,int f_tau,int f_tolA){
  
  vector&lt;double&gt; objective(2);
  
  //sth inside function
  
  return objective;
  
      }
  
      int main(){
          vector&lt;double&gt; objectives(maxiter+2);
          objectives=GPSR_BB(Y_MATRIX,A_MATRIX,tau,tolA);
          return 0;
      }
  </code></pre>
  
  <p>in line </p>
  
  <pre><code>vector &lt;double&gt; GPSR_BB(boost::numeric::ublas::matrix&lt;double&gt; &amp;f_Y_MATRIX,boost::numeric::ublas::matrix&lt;double&gt; &amp;f_A_MATRIX,int f_tau,int f_tolA){
  </code></pre>
  
  <p>I receive error</p>
  
  <pre><code>error: expected constructor, destructor, or type conversion before ‘&lt;’ token function
  </code></pre>
  
  <p>I guess, the problem is because of matrix data type, from boost library, which I have to pass to function, I don't think there is another way I can do for my specific problem.</p>
  
  <p>Any help is greatly appreciated. Thank you</p>