Nice one, Oleg. Yes, 1 and 0 should be the correct initial samples. Thanks
for this. :)
D
On Sun, 23 Jun 2019 at 18:56, Oleg Nesterov <o...@redhat.com> wrote:
> On 06/15, Dario Sanfilippo wrote:
> >
> > 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;
> > };
> > };
>
> another case when we need to initialize the delay line ;)
>
> Dario, it is not that I suggest to change this code, please ignore,
> but just for record... note that in this case we can avoid this hack
> and write
>
> quadosc(f) = tick ~ (_,_) : +(1),_ with {
> k1 = tan(f * ma.PI/ma.SR);
> k2 = 2*k1 / (1 + k1 * k1);
>
> tick(u_0,v_0) = u_1,v_1 with {
> tmp = u_0 - k1 * v_0;
> v_1 = v_0 + k2 * (tmp + 1);
> u_1 = tmp - k1 * v_1;
> };
> };
>
> This generates a slightly better code. And, this allows to add (mem,mem)
>
> quadosc(f) = tick ~ (_,_) : mem+1,mem with {
> k1 = tan(f * ma.PI/ma.SR);
> k2 = 2*k1 / (1 + k1 * k1);
>
> tick(u_0,v_0) = u_1,v_1 with {
> tmp = u_0 - k1 * v_0;
> v_1 = v_0 + k2 * (tmp + 1);
> u_1 = tmp - k1 * v_1;
> };
> };
>
> to ensure that it always ouputs (1,0) at the very first tick. Not that I
> think this is very important, but this matches other oscillators and looks
> more clean imo.
>
> Oleg.
>
>
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