[SciPy-dev] Reliability of linalg.eig for complex matrices A,B

Chuck Harris Chuck.Harris at sdl.usu.edu
Thu Aug 29 15:57:27 CDT 2002


from scipy import *
#
# Transcendental eigenvalue problem
#
# A(x) y = 0
#

You are looking for nontrivial vectors in the null space?
This isn't an eigenvalue problem, really, since you already
know the eigenvalue --- 0. 

necessary & sufficient condition:

determinant(A(x)) = 0

which is a zero finding problem. Solutions then follow by
reduction to row echelon form and back substitution.

#
# B(x) = -d A / d x
#

You doing linearization of an ODE? Or what?
 
> 
> 
> Hi,
> 
> I tried to solve a transcendental eigenvalue problem with scipy.
> However It works more or less for r e a l arguments x, but
> for complex arguments I cannot observe convergency to any 
> eigenvalue. I guess its a problem of the eigenvalue solver.
> Please find attached my small example.
> 
> Any ideas or suggestions ?
> 
> Nils
> 

Chuck 



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