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Re: I have modified firls.m to include all types of FIRs plus HT and dif


From: je suis
Subject: Re: I have modified firls.m to include all types of FIRs plus HT and diff
Date: Fri, 2 Jun 2017 15:19:34 +0000

> Have you read through Matlabs public documentation, including the algorithm
> section? Any insights there?
> https://www.mathworks.com/help/signal/ref/firls.html
>
> Do you gave access to either their primary algorithm reference:
> [1] Parks, Thomas W., and C. Sidney Burrus. Digital Filter Design. New
> York: John Wiley & Sons, 1987, pp. 54–83.
>
> Or this supplemental they mention in the algorithm section about some
> specific cases?
>
> [2] Oppenheim, Alan V., Ronald W. Schafer, and John R. Buck. Discrete-Time
> Signal Processing. Upper Saddle River, NJ: Prentice Hall, 1999.

All the numbers fit exactly for all your examples in this thread, and
I am willing to bet they will match for any other example, except the
part where no weighting is specified and a differentiator is used --
then, a 1/f^2 weighting scheme is used. This one is not referred to in
any of the Matlab's references, or Selesnick's paper (and
StackExchange didn't seem to be of very much help, either). So I used
the derivation that seemed right (according to my weak mathematical
skills, and the bit of help from StackExchange). It works, but with
hiccups, probably due to avoiding division by zero (which must be in
Matlab's script, too). This is the last barrier in having the exact
same results in both Octave and Matlab. I'll try it with MPFRC++ and
compare the results.

> Lastly, if you set up a github or other repository others might be willing
> to help hack your code. Keeping track of it via email is a bit tedious.

I never used github and I asked in this list because firls.m belongs
to Octave. But if you say that this way is not the preferred one, then
I'll use it.

Vlad



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