Given that the goal is to approximate the ideal filter with an IIR filter, why would it be easier to design it in the continuous time domain than the discrete?
This paper says:
Discrete time IIR filter design can be a very complex procedure in discrete time domain. Therefore, transformations have been developed to use well known design methods in continuous time domain.
This may be a very trivial question (sorry if it is), but I don't see why it is easier.
Perhaps I could be asking this in a better way: Why do we need to translate filter specifications from discrete to continuous time and then do the calculations in continuous time? Why not directly in discrete time?