eigenvalues, part: fell off the end



First of all, big thanks to all who replied 
trying to help. I deeply respect your effort, 
even if I'm unable to use the product effectively.

@Stavros: Actually, the matrix I need solved is 
somewhat more complicated. What I posted (and 
what still can't be solved, anyway) was the 
result of (over)simplification, symbolic 
variables assumed to be fractions of A, several 
parameters assumed to be 'equal' etc.

@Richard: I called it 'simple' because it can 
easily get quite un-simple. Posted (simplified) 
matrix was a Hamiltonian with 
cross-anharmonicities limited to neighbours 
third-removed. Hence lots of sparseness, uniform 
off-diagonal elements etc.

@Leo: The degree might get even higher. See 
above. As for the charpoly output -- well, the 
structure of eigenvalues output was ideal for my 
purposes, so I'm shying from digging in 
charpoly's. Of course, if I must, I must. I'd 
still prefer eigenvalues output, though.

@All: Can I generate the series approximation 
(in symbolic variables) in Maxima, for the 
exponential/matrix exponential? Preferrably, 
with adjustable cutoff (up to first, second 
powers)? Sections 26 and 28 of manual seem to be 
of no help.

-Yury