  We consider the model reduction problem for linear time-invariant dynamical
systems having nonzero (but otherwise indeterminate) initial conditions.
Building upon the observation that the full system response is decomposable as
a superposition of the response map for an unforced system having nontrivial
initial conditions and the response map for a forced system having null initial
conditions, we develop a new approach that involves reducing these component
responses independently and then combining the reduced responses into an
aggregate reduced system response. This approach allows greater flexibility and
offers better approximation properties than other comparable methods.
