[PD] different float accuracy betw. Pd-0.52-1-msw-i386 and Pd-0.52-1-msw-amd64

musil at iem.at musil at iem.at
Fri Feb 11 23:11:34 CET 2022

Zitat von Christof Ressi <info at christofressi.com>:

> That's only half the story. Generally, one shouldn't expect floating  
> point computations to yield the exact same result with different  
> compilers/machines. The rounding errors themselves are very small,  
> but they can accumulate over long periods of time or get amplified  
> by recursive algorithms.
> I've made an alternative implementation [biquad2~] that uses direct  
> form 1. It shows significantly less noise than the [biquad~]  
> examples. See attachments.

That's right what you wrote.
However, what worries me is that if I run a Pd vanilla patch on  
different Pd versions (i386 or amd64) with the same floating point  
precision, I expect the same results.

e.g. the test patch running on Pd-0.52-1-xxx-i386 produces -60dB low  
frequency spikes, the identical patch running on Pd-0.52-1-xxx-amd64  
produces -34dB high frequency bursts. And that's a realistic simple  
situation, a microphone signal feeds a 3rd order high pass filter.

Thomas Musil

-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: Test_HP3_butterworth_ at _20_Hz.pd
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20220211/ff112402/attachment.ksh>

More information about the Pd-list mailing list