[PD] rjdj, was : Re: [equalizer] / [lowshelf] / [highshelf] in purepd!

[Mathieu Bouchard]

On Sun, 29 Mar 2009, Frank Barknecht wrote:
> volker b?hm hat gesagt: // volker b?hm wrote:
>> thanks for posting this.
>> for certain freqs i hear a noticeable periodic "zipping" in the sound
>> (try 230 hz e.g.).
> Hm, I don't hear it, but that may be my ears.
>> since the algorithm is based on the sinc function (sin(x)/x), i wonder
>> how pd handles divide by zero in the signal domain. wouldn't you have to
>> check for that in the code/patch?
> A [/~] with no signal in the right inlet in Pd gives 0 as output.
> In saw~.pd x never becomes zero, it's always at least 1.8955. :)

Well, if divide-by-zero happens any often in there, it would be worthwhile 
to do an explicit check for divide-by-zero in the patch, because in this 
case 0/0 is expected to give 1, as all neighbouring values of sin(x)/x are 
getting closer to 1 as x gets closer to 0: that's what you need to make 
sin(x)/x a smooth function.

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