A method is presented for the direct and efficient computation of cert
ain characteristics of differential eigenvalue problems. The method is
based on the differentiation of the governing equations with respect
to one or more of the parameters of the associated dispersion relation
. The new problem (or problems), coupled with the original problem, is
solved to directly compute a certain required characteristic (e.g., t
he maximum disturbance growth rate). The method is applied to two prob
lems in boundary-layer stability: the viscous instability of incompres
sible flow over a flat plate with suction and the inviscid instability
of compressible flow over a flat plate with different wall and flow c
onditions. The new method has potential applications in both computati
onal physics and engineering. (C) 1995 Academic Press, Inc.