[PD] [sqosc~]-issues
Martin Peach
martin.peach at sympatico.ca
Tue Mar 27 02:23:23 CEST 2007
Does anyone know how to tell, in c, if you're getting nans? It should be
easy enough in the dsp routine to replace nans with zeros.
It's just a question of detecting them in time. I remember you could do
it in SANE, the old Apple math system, there was some function like isnan().
I don't see how [sqosc~] could be generating them though, since it's
deliberately operating in a fixed range of float, the same way [osc~] does.
Martin
Derek Holzer wrote:
> After having done lots of work with recursive feedback structures in PD
> using delays and filters, I can positively say that PD (rather then
> Jack) is making the problem in every one of my cases. YMMV. But for me,
> it always happens when delay lines or resonant filters become feedback
> saturated to the point of being pure DC. The offending object must then
> be cut and pasted (i.e. reset) to get rid of the "nan" signal, so try
> cut/paste rather than restart and see if it helps you next time. I've
> always considered this something that is inherent in DSP with no sanity
> checks, as PD often is, rather than a bug specific to PD. The CSound
> manual mentions this "blowing up" of filters quite frequently, so I know
> it happens in other applications.
>
> best,
> d.
>
> padawan12 wrote:
>
>> I get this too. It's never seemed worth filing a bug report
>> because it's not clear whether Pd or an external or Jack
>> itself it where the problem occurs. Sometimes a channel
>> just locks up and all I can get is nans until the application
>> is restarted. It's quite rare, but annoying if it happens
>> during a talk or performance.
>>
>
>
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