[PD] pow/pow~ and negative input, a fix proposal

Martin Peach chakekatzil at gmail.com
Wed May 9 18:53:47 CEST 2018


On Wed, May 9, 2018 at 10:38 AM, Alexandre Torres Porres <porres at gmail.com>
wrote:

> You know, now that you the inability to deal with nan/inf in pd, such as
> in [select] came up, it makes total sense to avoid them in Pd and I can see
> where that comes from.
>
> By the way, filtering out nan/inf is quite common in Max for audio
> signals, and in cyclone we needed to check that in objects like the trig
> functions (for instance  cyclone/atanh~ outputs 0 for input values <= -1 or
> >=1). And the case for doing that in audio signals is strong, as people say
> inf/nan is not good if it reaches your speakers and stuff.
>
> I was still unsure about why doing that for cnotrol numbers as well, but
> what's the point in generating them if your system doesn't handle it well,
> right? In the case of [pow], "0" is a good limit value to clip your output,
> it makes sense since you can't get negative numbers but you can reach 0!
>
> I just tried this in Max6:
[pow 2] with a negative input gives a correct positive result.
[pow 0.5] with negative input sets a floatnumberbox to 'nan', but [print]s
the value '-1.#IND00'.
 In max, neither of these works in a [sel].

Martin
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