Ok, thanks. I guess that nobody uses large signals for that.
----- Mail d'origine ----- De: Miller Puckette msp@ucsd.edu À: Nicolas Danet nicolas.danet@free.fr Cc: pd-dev@lists.iem.at Envoyé: Sat, 26 Nov 2016 14:59:10 +0100 (CET) Objet: Re: [PD-dev] cos and large amplitude signal in?
I dno't know how well known it is (it really should be mentioned in the documentation) but taking cosines of large numbers fails. In fact, accuracy starts to drop audibly when the input exceeds about 100 in absolute value, because you are then eating 8 bits of the 24-bit mantissa to specify teh integer part of teh index, leaving only about 16 for the fraction. The situation degrades steadily as the numbers grow past that.
cheers Miller
On Sat, Nov 26, 2016 at 02:44:13PM +0100, Nicolas Danet wrote:
Hi,
The cos signal object seems to give bad results for a large amplitude signal in (> 1024). As far as i understand it is limited to (2^19 / COSTABSIZE) due to the fractional trick here < https://sourceforge.net/p/pure-data/pure-data/ci/master/tree/src/d_osc.c#l17... >.
Is it a well known limitation?
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