[PD] problem with correct numbers in pd double precision

hans w. koch hansw.koch at gmail.com
Sat Sep 19 09:16:52 CEST 2020


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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