A Recursive Filtering Workbench
The complete collection of installments presents and explains the code for an interactive Recursive Filtering Workbench that can be used to design, experiment with, and evaluate the behavior of digital recursive filters.
By the end of the last installment, you should have learned how to write a Java program to create such a workbench. Hopefully, you will also have gained some understanding of what recursive filters are, how they behave, and how they fit into the larger overall technology of Digital Signal Processing (DSP).
Viewing tip
You may find it useful to open another copy of this lesson in a separate browser window. That will make it easier for you to scroll back and forth among the different listings and figures while you are reading about them.
Complex poles and zeros
The workbench makes it possible for the user to design a recursive filter by specifying the locations of sixteen poles and sixteen zeros in the complex z-plane and then to evaluate the behavior of the recursive filter for that set of poles and zeros. The user can relocate the poles and zeros and re-evaluate the behavior of the corresponding recursive filter as many times as may be beneficial without a requirement to restart the program.
Read full article at softwaredevelopmentblog.com 
