Modal analysis using gnucap

Hi,

I've been using gnucap for modelling pneumatic transmission lines with LCR
equivalents. This linear AC analysis is working very nicely and the results
are as expected. Now I'm wondering if it is possible to do a modal analysis
of the whole system. That is, I would like to know the poles, zeros and mode
shapes of the system. Is this possible to do in gnucap? If this is not
implemented, would it be possible to maybe export the matrices generated for
the system and solve the eigenvalue problem in another package? I don't know
a lot about how the AC analysis is implemented so maybe I'm not making
sense, but any help would be appreciated. Best regards,

Jasper