Algorithm for conv, filter

[Steve C. Thompson]

Hi,

I've got $5 on: `conv (a, b)' is implemented as `ifft (af, bf)'
where AF and BF are the FFTs of A and B (roughly speaking).
Trying to prove this, I glanced at the octave source code for
`conv' and I see that it calls `filter'.  (From what I
understand, `filter' and `conv' are essentially the same but
`conv' returns a complete convolution while `filter' truncates
the samples.)  However, I can't figure out what `filter' does
since I can only find the .oct file on my computer---Linux
version 2.6.12-9-686 (gcc version 3.4.5 20050809 (prerelease)
(Ubuntu 3.4.4-6ubuntu8)); GNU Octave, version 2.1.71
(i486-pc-linux-gnu)---I'm not sure what filter is doing.

Does the algorithm in `filter' take the IFFT of two FFTs?

Thanks in advance.

Steve



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