[maxmsp] IIR/FIR external & Freq Response

On 13 Jan 2008, at 19:36, Jam wrote:

>
> Hi there,
>
> I am currently coding various IIR and FIR filters using co- 
> effecients from MATLAB for bandpasses at very low frequencies (0  
> -40 Hz) with very small bandwidths (around 6 Hz).
>
> However once I have them coded is there any real way within Max to  
> view the freq/magnitude response of my filters?

well, from the coefficients you could derive the filter transform  
function and from this calculate the freq response, but you
probably want to meassure the response to verify your code, right?

so why not send a unit impulse (click~) into your filter and record  
the output into a buffer?
then do an fft on the buffer to view the freq response.

with very narrow bandpasses the impluse response can get quite long.
also for low frequencies you would need very large fft sizes...
somewhere i have an external lying around that performs ffts of long  
buffers (nonrealtime ) that i would be happy to share.
it only needs a help file.
but this is for osx only.

volker.