[eigen] bug in data() on col/row

[Benjamin Schindler <bschindler@xxxxxxxxxxx>]

Hi

I just discovered a nasty "bug" - depending on how you look at it -  in
Eigen, see the following program:

#include <eigen2/Eigen/Core>

using namespace Eigen;
using namespace std;

void copy(const float *from, float *to)
{
    for(int i=0;i<3;i++)
        to[i] = from[i];
}

int main(int argc, char** argv)
{
    Matrix3f m;
    m << 1,2,3,4,5,6,7,8,9;
    cout << m << endl << endl;
    float var[3];
    copy(m.row(0).data(), var);
    Map<Vector3f> map(var);
    cout << map.transpose() << endl;
}

bschindl@hundertwasser ~ $ ./test
1 2 3
4 5 6
7 8 9

1 4 7

When I save m.row(0) in a Vector3f and output it, I of course get this:


bschindl@hundertwasser ~ $ ./test
1 2 3
4 5 6
7 8 9

1 2 3

That's a nasty thing - and can cause lots of pain...
Is there something we can do about it?

Cheers
Benjamin