[PD] problem with correct numbers in pd double precision

hans w. koch hansw.koch at gmail.com
Sat Sep 19 10:49:51 CEST 2020


arrghhh…sometimes live can be so easy :-)

cheers 
hans

> Am 19.09.2020 um 10:45 schrieb Lucas Cordiviola <lucarda27 at hotmail.com>:
> 
> I think you can convert symbol back to float just using [f ].
> 
> [123123123(
> |
> [makefilename %f]
> |
> [t a 0]
> |     |
> [text set foo]
> 
> 
> 
> [0(
> |
> [text get foo]
> |
> [f ]
> |
> [print]
> 
> 
> :)
> 
> Mensaje telepatico asistido por maquinas.
> 
> On 9/19/2020 4:16 AM, hans w. koch wrote:
>> thanks lucas,
>> 
>> transitioning numbers over to symbolland could solve my problem, interesting to know.
>> 
>> i need to store some of the big numbers in a textfile and there i get the same problems with representation.
>> if i recall them later, they´ve lost their precision.
>> so i can make the transition back from symboldland with a bit of fudi objects voodoo and be good :-)
>> 
>> what i use is this:
>> [makefilename %f]
>> |
>> [list trim symbol]
>> |
>> [fudiformat -u]
>> |
>> [fudiparse]
>> 
>> and have my number back from symbol.
>> 
>> best
>> hans
>> 
>> 
>> 
>>> Am 19.09.2020 um 05:32 schrieb Lucas Cordiviola <lucarda27 at hotmail.com>:
>>> 
>>> If you want to print the numbers nicely to the console add [makefilename %f] :
>>> 
>>> [t b f]
>>>       |
>>>       [makefilename %f]
>>>       |
>>>       [print count]
>>> 
>>> 
>>> Be aware of https://github.com/pure-data/pure-data/issues/812
>>> 
>>> :)
>>> 
>>> Mensaje telepatico asistido por maquinas.
>>> 
>>> On 9/18/2020 6:12 PM, hans w. koch wrote:
>>>> hello,
>>>> 
>>>> its probably due to my lack of understanding the correct number representations, but here it goes anyway:
>>>> 
>>>> i compiled pd 51-2 double precision for mac 10.14.6
>>>> with this version i was hoping to do some maths on big numbers.
>>>> but already an increment of 1 on some moderatly big number gives me problems of representation.
>>>> 
>>>> i made a simple version of the problem as a patch.
>>>> to verify you have a working version of pd double, it contains a simple test.
>>>> and then an iterative addition +1 starting from 999999.
>>>> i get this:
>>>> count: 999999
>>>> count: 1e+06
>>>> count: 1e+06
>>>> count: 1e+06
>>>> count: 1e+06
>>>> count: 1e+06
>>>> count: 1.00000e+06
>>>> count: 1.00001e+06
>>>> count: 1.00001e+06
>>>> count: 1.00001e+06
>>>> 
>>>> the algorith terminates succesfully by a [select] after 10 iterations, but the results don´t show what i expect.
>>>> this to me indicates, that the internal numbers are correct, but they don´t “surface” as such.
>>>> 
>>>> i would be grateful for any pointers and possible workarounds, as the numbers i hope to be dealing with are potentially orders of magnitude higher.
>>>> 
>>>> thanks hans
>>>> 
>>>> 
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