ba.take() ==> O(n)
but par(i, n, ba.take()) ==> O(n^2)
-------------------------
Yann Orlarey
Directeur scientifique
www.grame.fr
2018-03-20 5:26 GMT-07:00 Stéphane Letz <[email protected]>:
> ba.take ==> complexity O(n^2)
>
> I think that this kind of info should be added in the library
> documentation.
>
> And also as a general rule in the « Contributing » section of
> https://github.com/grame-cncm/faustlibraries/blob/master/README.md, to
> push library writers to document this kind of things.
>
> Stéphane
>
>
> > Le 20 mars 2018 à 04:32, Yann Orlarey <[email protected]> a écrit :
> >
> > HI,
> >
> > I did some tests and I don't see any problem with fi.fir(), it supports
> very large lists. Here is the test file I used:
> >
> > // ------- fir500.dsp ------
> >
> > import("stdfaust.lib");
> >
> > process = fi.fir((
> > 1,2,3,4,5,6,7,8,9,10,
> > ...48 copies...
> > 1,2,3,4,5,6,7,8,9,10));
> >
> > //---------------------------------
> >
> > time faust fir500.dsp -o /dev/null
> >
> > real 0m0.446s
> > user 0m0.375s
> > sys 0m0.030s
> >
> >
> > If instead, I use the second code you mentioned
> >
> > // ------- fur500.dsp ------
> >
> > import("stdfaust.lib");
> >
> > fur(coeffs) = _ <: par(i, 500, @(i) * ba.take(i + 1, coeffs)) :> _;
> >
> > process = fur((
> > 1,2,3,4,5,6,7,8,9,10,
> > ...48 copies...
> > 1,2,3,4,5,6,7,8,9,10));
> >
> > //---------------------------------
> >
> > The compilation will take a very long time because ba.take() is really
> not the way to go in this case (complexity O(n^2)). Here are the results I
> get:
> >
> > time faust fur500.dsp -o /dev/null
> >
> > real 1m18.270s
> > user 1m16.947s
> > sys 0m0.900s
> >
> > The difference is enormous (x170)!
> >
> > If in your case you don't see any difference of performances between the
> two, then there is a problem with the fi.fir implementation you are using.
> >
> > Can you try with the latest version of Faust (version 2.5.25)?
> >
> > Cheers
> >
> > Yann
> >
> >
> >
> >
> >
> > 2018-03-19 15:01 GMT-07:00 Oliver Larkin via Faudiostream-users <
> [email protected]>:
> > depending on what faust version you are using, a foreign function might
> help. I had to do this to do a convolution in my tambura synthesiser for
> exactly the same reason
> >
> > https://github.com/olilarkin/Tambura/blob/master/bridgeIR.dsp
> >
> > https://github.com/olilarkin/Tambura/blob/master/bridgeIR.h
> >
> >
> > it would be great if faust’s FIR didn’t bork like this
> >
> > oli
> >
> >
> >> On 19 Mar 2018, at 21:32, CrocoDuck o'Ducks <[email protected]>
> wrote:
> >>
> >> Hi again!
> >>
> >> Thank you for all your tips!
> >>
> >>> I suggest placing all of your coefficients into a large parallel
> signal bank:
> >>>
> >>> coeffs = (b0, b1, b2, ..., b511); // FIR filter coefficients for
> length 512
> >>>
> >>> and then use par() etc.
> >>
> >> I tried both of these:
> >>
> >> process = fi.fir(coeffs);
> >>
> >> process = _ <: par(i, 512, @(i) * ba.take(i + 1, coeffs)) :> _;
> >>
> >> Which, unfortunately, both suffer from the same problem. Did I got the
> suggestion right?
> >>
> >>> You can set unlimited time by adding
> >>> -t 0
> >>> to your compile command.
> >>
> >> I am currently trying this.
> >>
> >>> Interesting ! Do you have some code to show? Is is part of an official
> JULIA ==> Faust project?
> >>
> >> No, it isn't an official project. I just design some filters using
> DSP.jl then I try to generate Faust code that implements them. I just open
> a file for writing and I fill it with Faust code. I guess I can cook a few
> minimal examples to share, I cannot share my code right away as it is sort
> of confidential.
> >>
> >> On Mon, 19 Mar, 2018 at 8:20 AM, Stéphane Letz <[email protected]> wrote:
> >>>
> >>> Le 18 mars 2018 à 23:06, CrocoDuck o'Ducks <
> [email protected]
> >>> > a écrit :
> >>>
> >>> Hi there!
> >>>
> >>> I currently have some Julia code producing 512 taps for an FIR filter.
> >>>
> >>>
> >>> Interesting ! Do you have some code to show? Is is part of an official
> JULIA ==> Faust project?
> >>>
> >>> Stéphane
> >>>
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