Filter design as a research subject dates almost a century now. Of course, it was
coming as part to the development of the radio and telecommunication industry
which became ubiquitous now. Substantial number of solutions was offered in
transfer function synthesis as well as in the physical realization which gradually
shifted from analogue to a digital one with the ability to be even implemented as
software. In that, the interest got shifted mainly towards new technologies while
gradually narrowing the scope and the versatility of the approximation solutions. As
a consequence, modern filter design is based on reduced set of transfer functions
being catalogued and available broadly.
It was our filling that in the historical moment, we are living catalogues and
nomograms are not the best way to produce optimal solutions. That is valid
especially having in mind the fact that the computers became affordable to anyone
and that practically all electrical engineers are fluent in programming languages. We
think that the theory and numerical receipts given, anyone may produce any
practically feasible transfer functions starting with the proper set of requirements.
Similar stands for the circuit or system synthesis.