L/sup 1/ approximation of a certain class of infinite dimensional systems in time-domain

To the class of stable infinite dimensional systems whose impulse response functions decay to 0 exponentially, lower dimensional systems are designed in this paper by using the Laguerre series expansion that approximate the infinite dimensional systems in time-domain under L¹ norm, and the approximation orders are derived. As applications, the results on the approximation of stable general retarded delay systems are established.