[PD] time-domain Fir filters

[João Miguel Pais]

Dear list,

Based on texts from electronics classics, I made a patch in which a FIR
filter is built as defined by its difference equation. I was hoping to to
try to understand better this resource, it would have a didactical purpose
(since there are already better implemented filters).
But after creating the patch, I realized that I couldn't make it work
properly, because I didn't knew how to calculate the difference equation for
a type of filter (say, for example, a 1000Hz low-pass).

I put the patch in http://home.arcor.de/jmmmp/. I would like to ask if with
this patch it is really possible to define a filter, or there is something
missing. And if possible, how to calculate the coefficients.

Thanks,

João Miguel Pais