Consider the mass-spring system introduced in
§2.1. If the system is undamped,
it will continue to vibrate forever once started.
The question we ask is, Can the user grab and
move one of the masses, say the th one, in such a
way as to eventually bring all the masses to rest?
The question is about *controllability*, and the
answer depends both on the value of and on the
number and values of the spring constants.
The calculation involves computing the smallest
reducing subspace of
, where
is defined in (2.4)
and depends on .

only discuss a few special nonlinear eigenproblems, we cannot say much about its general theory.

Susan Blackford 2000-11-20