I am trying to implement some code to firstly generate an Octave-Band and Fractional-Octave Band filter. I have used MATLAB's octaveFilter method to generate compliant Class-1 and Class-0, 1/1 and 1/3 Octave band filters, but I want to understand how to design these filters from scratch so I can better understand their construction. Then I want to go on to implement in code. So the coding environment doesn't matter, but I want to understand the filter construction from the filter definition/algorithm.
My problem is that the documentation for MATLAB's octaveFilter method doesn't explain the algorithm used to create the filters, nor does it explain how the filter is applied to data programmatically.
Can someone please point me to some material that explains how to create these filters, for any centre frequency I choose, and then implement in code? Many thanks!