By a simple extension of the Method of Lines, the ordinary differential equ
ation solver VODPK may be used to solve a certain class of integro-differen
tial equation systems (IDE systems). The problems are characterized by a pa
ir of advected frequency-dependent quantities, coupled to a population vari
able whose rate includes a spectral integral in one space dimension. We hav
e found that with an appropriate choice of preconditioner to aid in the con
vergence of the linear iterations, an extremely efficient method is obtaine
d for the solution of these types of IDE system problems. We discuss the se
midiscretization process and the formation of the preconditioner in some de
tail. Finally, we present an application of the technique. (C) 2001 Academi
c Press.