Re: [LAD] Is -ffast-math safe for audio?

2018-11-23 Thread Hermann Meyer
Am 22.11.18 um 22:41 schrieb Fons Adriaensen: On Thu, Nov 22, 2018 at 09:27:58PM +0100, Hermann Meyer wrote: In guitarix nearly all DSP is generated by FAUST. That doesn't make any difference for numerical stability. This is a property of an algorithm, not of the language. Ciao, Just as

Re: [LAD] Is -ffast-math safe for audio?

2018-11-23 Thread Tim
On 11/23/2018 09:18 AM, Gordonjcp wrote: On Fri, Nov 23, 2018 at 02:09:02PM +0100, Robin Gareus wrote: On 11/23/2018 01:00 PM, Will Godfrey wrote: [...] Thanks for going into this in such detail Robin. I never realised fp stuff could be *quite* so, umm, approximate! Depending on context

Re: [LAD] Is -ffast-math safe for audio?

2018-11-23 Thread Nikita Zlobin
In Fri, 23 Nov 2018 17:56:38 + Gordonjcp wrote: > On Fri, Nov 23, 2018 at 10:33:24PM +0500, Nikita Zlobin wrote: > > In Fri, 23 Nov 2018 14:18:01 + > > Gordonjcp wrote: > > > > > On Fri, Nov 23, 2018 at 02:09:02PM +0100, Robin Gareus wrote: > > > > On 11/23/2018 01:00 PM, Will

Re: [LAD] Is -ffast-math safe for audio?

2018-11-23 Thread Gordonjcp
On Fri, Nov 23, 2018 at 10:33:24PM +0500, Nikita Zlobin wrote: > In Fri, 23 Nov 2018 14:18:01 + > Gordonjcp wrote: > > > On Fri, Nov 23, 2018 at 02:09:02PM +0100, Robin Gareus wrote: > > > On 11/23/2018 01:00 PM, Will Godfrey wrote: > > > [...] > > > > Thanks for going into this in such

Re: [LAD] Is -ffast-math safe for audio?

2018-11-23 Thread Nikita Zlobin
It's probably gonna be silly question, but after short analysis i don't see, what could be broken in this demo snippet, when float is standard single-precision 32bit type. I omit first case, as optimizing compiler could just optimize it to just =1; though it could do it in second case too... (as

Re: [LAD] Is -ffast-math safe for audio?

2018-11-23 Thread Nikita Zlobin
In Fri, 23 Nov 2018 14:18:01 + Gordonjcp wrote: > On Fri, Nov 23, 2018 at 02:09:02PM +0100, Robin Gareus wrote: > > On 11/23/2018 01:00 PM, Will Godfrey wrote: > > [...] > > > Thanks for going into this in such detail Robin. I never realised > > > fp stuff could be *quite* so, umm,

[LAD] [ANN] QjackCtl 0.5.5 - A Black-Friday'18 Release

2018-11-23 Thread Rui Nuno Capela
Wholly greetings! QjackCtl 0.5.5 (black-friday'18) is released! QjackCtl [1] is a(n ageing yet modern, not so 'simple' anymore) Qt [2] application to control the JACK [3] sound server, for the Linux Audio [5] infrastructure. Website: https://qjackctl.sourceforge.io

Re: [LAD] Is -ffast-math safe for audio?

2018-11-23 Thread Nikita Zlobin
It could be lame question, but still... is it possible, that some implementations (compiler/hardware) will print 1? (even 64bit doesn't hold 20 decimal digits).? In Fri, 23 Nov 2018 14:09:02 +0100 Robin Gareus wrote: > On 11/23/2018 01:00 PM, Will Godfrey wrote: > [...] > > Thanks for going

Re: [LAD] Is -ffast-math safe for audio?

2018-11-23 Thread Gordonjcp
On Fri, Nov 23, 2018 at 02:09:02PM +0100, Robin Gareus wrote: > On 11/23/2018 01:00 PM, Will Godfrey wrote: > [...] > > Thanks for going into this in such detail Robin. I never realised fp stuff > > could be *quite* so, umm, approximate! > > Depending on context and the maths, the difference may

Re: [LAD] Is -ffast-math safe for audio?

2018-11-23 Thread Robin Gareus
On 11/23/2018 01:00 PM, Will Godfrey wrote: [...] > Thanks for going into this in such detail Robin. I never realised fp stuff > could be *quite* so, umm, approximate! Depending on context and the maths, the difference may not matter at all, or may be off completely.. float a = (1 + 1e20) -

Re: [LAD] Is -ffast-math safe for audio?

2018-11-23 Thread Will Godfrey
On Thu, 22 Nov 2018 23:29:11 +0100 Robin Gareus wrote: >Hi Will, > >I just ran your code and -ffast-math does not make any difference. > >With or without --ffast-math I get "int: 5 rem: 0.049994" > >However optimizing the code with `-O2 --ffast-math` does make a >difference because SSE is used.