[PD] strange bug [f], Pd 0.45.5

Jonghyun Kim agitato816 at gmail.com
Sun Oct 5 20:40:19 CEST 2014


Thanks for the solution. I can understand the actual problem on 32bit. But
I think still this is a bug.

|
> | +------+
> [f]      |
> |        |
> [+ 1]    |
> |        |
> [% 6]    |
> |        |
> [t f f]  |
> |     +--+
> |


Could you give me the patch again with easily drawing? Sorry I can't
recognize your patch drawing...

Many thanks,
akntk

On Mon, Oct 6, 2014 at 1:22 AM, <zmoelnig at iem.at> wrote:

> (had to find a real compuer before anwering the actual question)
>
>
> Quoting Jonghyun Kim <agitato816 at gmail.com>:
>
>> Pd 0.45.5 (Vanilla)
>> Mac OS X Mavericks 10.9.5
>>
>>
>> I don't really know why this bug cause, or only my problem. This bug
>> sometimes appears. I think this is very critical bug.
>> [f] storing bug
>>
>> [metro 1]
>> |
>> [f 0]
>> |  /
>> [+ 1]
>> |
>> [% 6]
>>
>> respected result: 0, 1, 2, 3, 4, 5 (repeat)
>>
>> bug: 4, 4, 4, 4, 4 (always 4)
>>
>
>
> this very much sounds like a problem with floating point precision overrun.
> an [f] object (and actually *any* number within the Pd universe) will hold
> a single precision 32bit floating point number, which can only represent
> *consecutive* integer values up to 16777216.
> (consecutive means, that [f] can hold representations of both (e.g.)
> 1000023 and 1000024).
> if the numbers go higher, singple precision floats will have gaps bigger
> than 1.0 inbetween them (e.g. the next number after 16777216 representable
> by [f] is 16777218) - this breaks a counter that increments 1 (since
> 16777216+1 will be evaulated to ~16777216!)
>
> the solution is actually quite simple: never allow your number to grow as
> big as that.
>
> in your counter this means, that the feeback part, must include the [% 6]
> (so the numbers in the counter will only ever stay in the range 0..6):
>
> |
> | +------+
> [f]      |
> |        |
> [+ 1]    |
> |        |
> [% 6]    |
> |        |
> [t f f]  |
> |     +--+
> |
>
> btw, you ASCII rendering of the patch did not use [trigger]. you should
> always use it when you want to connect multiple inlets to a single outlet.
>
> mfgsdr
> IOhannes
>
>
>
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