[PD] why does PD round numbers? (in tables, in messageboxes, etc)

[Matteo Sisti Sette]

Whops, I should have read the other replies first :$

On 04/09/2012 01:23 AM, Matteo Sisti Sette wrote:
> On 04/08/2012 04:27 PM, katja wrote:
>
>> I've once compiled (vanilla) Pd with the format specifiers changed to
>> print up to 8 significant digits, and soon found why it is normally
>> done with 6 digits max. You get things like this:
>>
>> 33 * 0.3 = 9.900001
>
> That is completely unrelated. That is an issue intrinsic in floating
> point numbers.
>
> Reducing the precision of numbers when writing them to files (or when
> parsing messages or whatever) is an issue in Pd.
>
> One thing is rounding numbers for _displaying_ them, another thing is
> rounding them when _storing_ them (whether in a file or wherever).
>
> Consider this: I create a patch like this:
>
> [9.900001(
> |
> [== 9.9]
> |
> [print]
>
> This prints 0, as expected.
>
> Then I save and close it. I load it, and it has been transformed into this:
>
> [9.9(
> |
> [== 9.9]
> |
> [print]
>
> which obviously prints 1.
>
> This is WRONG, there's no reason why it could be good or even
> acceptable. I do understand why it happens.
>
>
> By the way, if you write into an object box:
>
> [f 9.90001]
>
> it is immediately changed into: [f 9.9]
>
> Which is also WRONG (why shouldn't I be able to create an object with a
> parameter value which _can_ be represented without loss of
> information?), but it is much "less wrong" than the previous case in
> that this is CONSISTENT. In this case, at least, "what you have is what
> you save" (note that "what you see" is not an issue).
>
> The case of message boxes (not to mention arrays) is devastating,
> because you may not realise you're going to loose information until you
> save the patch, close and reopen it.