I have a set of points. I would like to calculate eigen vectors for that point sets. Could any one help me how that can be done. Thanks.

an eigenvector q is a vector which solves M*q=lambda*q with M being a matrix and lambda being a scalar value. i do not see any relation to a point set there.

Do you mean eigen-vectors that defines the orientation of the box that minimizes the volume wich enclosing the point cloud?

I meant that. I found VTK has an implementation of that vtkOBBTree.cxx. This helped me understand how to construct eigen vectors from a set of points.