[PD] long int precision lost

Marc Boon marcboon at dds.nl
Sun Dec 5 20:21:45 CET 2004

Mathieu Bouchard wrote:

> On Sun, 5 Dec 2004, Lex Ein wrote:
>>At first glance, Microsoft C and GNU both provide quite adequate
>>double and long double mantissa size, so the existence of this data
>>degradation is odd.
> Pd Floats are 32-bit, or 1:8:23-bit to be exact. So you can't have more
> than 24 significant bits, and so (1<<24)+1 = 16777217 is the first integer
> not representable as a float (it gets rounded).
> Pd is currently pretty much stuck to float32, Miller having refused the
> int/float separation and any kind of number type distinction; there is no
> provision for anything other than float32.
> So if you want more precision you will have to cut down your data into
> smaller pieces, or use something else than Pd for handling those values
> that need more precision. Some of the scripting languages connectable to
> Pd support float64 and/or illimited-precision integers (both Ruby and
> Scheme have those two types; Python must have something similar too)

I agree with Lex that float64 aka double would be a better choice than float32, 
since all current hardware has 64-bit fpus anyway, it would hardly present a 
performance penalty, besides the obvious increase in memory usage.

Maybe you could just recompile Pd with a '#define float double' ?

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