Eigenvalues

[Przemyslaw Sliwa]

Hi people,

I would like to ask all of you something. 
I have a matrix function, which is given by 
the modulus of the i-th eigenvalue of a real n*n matrix.
So finally I have a matrix, which has dimension n (n*1 vector).
Does anybody know how to compute the jacobian of such a matrix? 
I need to compute the partial derivatives of the i-th modulus with
respect to the matrix.

Thanks for any ideas and help

Przem