Hi,

I'm sorry for my english, i'm french.

I'm developing a linar algebra program for Delphi which computes eigenvalues and eigenvectors of a matrix.

For general Matrix i use the complex Schur decomposition to find eigenvalues.

To find eigenvectors i use the upper triangular matrix T from the shur decomposition and i simply solve the system T*X=v*X where v is an eigenvalue computed before.

It works most of the time, but when eigenvalues vary quite a bit in size, the eigenvectors computed are not precise at all.

So, my question is: Is there other methods to find eigenvectors of a non-hermitian matrix when some eigenvalues are "almost degenerated"?

In particular, what is the algorithm used by LAPACK ?

Thank you for your answers.