86.1 Introduction The convolution sum description of an LTI discrete-time system can, in principle, be used to implement the system For an IIR finite-dimensional system this approach is not practical as here the impulse response is of infinite length However, a direct implementation of the IIR finite-dimensional system is practica• The convolution sum description of an LTI discrete-time system can, in principle, be used to implement the system • For an IIR finite-dimensional system this approach is not practical as here the impulse response is of infinite length • However, a direct implementation of the IIR finite-dimensional system is practical §6.1 Introduction