Hi, Julius. Thanks for adding the code.
I remember that I implemented the algorithm in Lua a couple of months ago and I let it go for maybe half an hour with the frequency changing randomly at each sample with values from 0 to Nyquist and it was still stable after that. The test was double-precision. I'll see if I can more tests including the other oscillators. Cheers, Dario On Mon, 17 Jun 2019 at 23:21, Julius Smith <j...@ccrma.stanford.edu> wrote: > Hi Dario, > > Ok, this looks promising. I have added the below to oscillators.lib. > Let me know if you'd like to see any changes. Test results welcome, > especially comparisons to the other oscillators, e.g., > > f = 1000; > oscs = (os.quadosc(f), os.oscrq(f), os.oscs(f), os.oscq(f)); > process = oscs; > // study classic corner cases such as those mentioned in > https://vicanek.de/articles/QuadOsc.pdf > > Thanks, > - Julius > > //-----------------`(os.)quadosc`-------------------- > // Sinusoidal oscillator based on QuadOsc by Martin Vicanek > // > // #### Usage > // > // ``` > // quadosc(freq) : _ > // ``` > // > // where > // > // * `freq`: frequency in Hz > // > // #### Reference > // * <https://vicanek.de/articles/QuadOsc.pdf> > //------------------------------------------------------------ > // Author: Dario Sanfilippo <sanfilippo.da...@gmail.com> (jos ed.) > quadosc(f) = tick ~ (_ , _) > with { > init = 1-1'; > w = 2*ma.PI*f/ma.SR; > k1 = tan(.5*w); > k2 = 2*k1/(1+k1*k1); > tick(u, v) = omega-k1*(v+k2*omega) , v+k2*omega > with { > omega = (u+init)-k1*v; > }; > }; > > On Mon, Jun 17, 2019 at 11:50 AM Dario Sanfilippo > <sanfilippo.da...@gmail.com> wrote: > > > > Hi, Julius. > > > > I haven't experienced a particular case where this oscillator would be > better than others yet but according to table1 in the aforementioned paper > it does seem to be the best design, doesn't it? I'm not sure it is > computationally heavier than the others. > > > > Though I have a work which is a self-oscillating FDN with frequency > shifters in the loops that shift the signals of a very small fraction of > Hz. For that, I'd need a very low frequency quadrature oscillator and, > according to the table, Biquad, DWG and QSU would not be accurate for that. > > > > Cheers, > > Dario > > > > > > > > On Mon, 17 Jun 2019 at 20:39, Julius Smith <j...@ccrma.stanford.edu> > wrote: > >> > >> Hi Dario, > >> > >> I don't see its unique advantage(s). Can you make a case for it over > >> the oscillators already in oscillators.lib? > >> > >> Thanks, > >> - Julius > >> > >> On Sat, Jun 15, 2019 at 5:04 AM Dario Sanfilippo > >> <sanfilippo.da...@gmail.com> wrote: > >> > > >> > Described in this paper: https://vicanek.de/articles/QuadOsc.pdf. > >> > > >> > If I'm not wrong, it's not in the oscillators library yet so it could > be a good addition. > >> > > >> > Cheers, > >> > Dario > >> > > >> > import("stdfaust.lib"); > >> > quad_osc(f) = tick ~ (_ , _) > >> > with { > >> > init = 1-1'; > >> > w = 2*ma.PI*f/ma.SR; > >> > k1 = tan(.5*w); > >> > k2 = 2*k1/(1+k1*k1); > >> > tick(u, v) = omega-k1*(v+k2*omega) , v+k2*omega > >> > with { > >> > omega = (u+init)-k1*v; > >> > }; > >> > }; > >> > process = quad_osc(1000); > >> > _______________________________________________ > >> > Faudiostream-users mailing list > >> > Faudiostream-users@lists.sourceforge.net > >> > https://lists.sourceforge.net/lists/listinfo/faudiostream-users > >> > >> > >> > >> -- > >> > >> Julius O. Smith III <j...@ccrma.stanford.edu> > >> Professor of Music and, by courtesy, Electrical Engineering > >> CCRMA, Stanford University > >> http://ccrma.stanford.edu/~jos/ > > > > -- > > Julius O. Smith III <j...@ccrma.stanford.edu> > Professor of Music and, by courtesy, Electrical Engineering > CCRMA, Stanford University > http://ccrma.stanford.edu/~jos/ >
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