23 Jul
2004
23 Jul
'04
6:29 p.m.
Sudheer Phani wrote:
Hello All,
I have been encountering some strange problems with the calculation of eigen vectors using python. The problem is with the sign of the eigen vectors calculated. On Very few occasions the eigen vectors calculated using python have an opposite sign than the actual eigenvectors, though the magnitude is correct.
Eigenvectors are defined only up to a scalar normalization constant. What do you mean exactly by opposite sign? If x is an eigenvector for A*x = s*x (s being the eigenvalue) then obviously A*(-x) = s*(-x) so -x is also an eigenvector with the same eigenvalue (or a.x for a being any scalar). Best, f