[ublas] creating a zero vector

From: ZhiQiang Chen (zqc.chen_at_[hidden])
Date: 2005-09-17 13:30:58

Dear all,

I found some weird error in the following code:

//////////////////////////////////////////////////////////////////////
#include <boost/numeric/ublas/io.hpp>
#include <boost/numeric/ublas/matrix.hpp>
#include <boost/numeric/ublas/vector.hpp>

using std::cout;
using std::endl;

int main()
{
 namespace ublas = boost::numeric::ublas;
 using namespace ublas;

 typedef ublas::vector<double> Vector;
 typedef ublas::matrix<double> Matrix;
 typedef ublas::zero_vector<double> ZeroVec;
 typedef ublas::zero_matrix<double> ZeroMat;
 typedef Vector::size_type size_type;

 size_type N = 5;

 Matrix mat(ZeroMat(N, N)); // works fine

 Vector vec(ZeroVec(N)); // error incurred when compiled
 // Vector vec(ZeroVec(N +1 -1)); // works fine
 // Vector vec(ZeroVec(5)); // works fine

 // ZeroVec _v(N); Vector vec(_v); // works fine

cout << "mat = " << mat << endl;
cout << " vec = " << vec << endl;

 return 0;
}
///////////////////////////////////////////////////////////

The error message is:

warning: the address of `main()::Vector
 vec1(boost::numeric::ublas::zero_vector<double>)', will always be `true'
/tmp/cc2twKnI.o(.text+0x147): In function `main':
: undefined reference to `vec1(boost::numeric::ublas::zero_vector<double>)'
collect2: ld returned 1 exit status

So is it a bug over there? or something I haven't understood.

Thanks.

=======================
ZhiQiang Chen
Doctoral Student, VIS Lab, UCI
=======================