[PD] I'm stuck in a corner, please help! RE: [delta~] object was: Re: Cyclone in vanilla?

Miller Puckette mpuckett at imusic1.ucsd.edu
Fri Apr 25 17:14:05 CEST 2008


I think this is my mistake -- as someone else pointed out, it should have
been "rzero_rev~", not "rzero 1" -- sorry for the confusion.

Miller

On Fri, Apr 25, 2008 at 04:08:38PM +0100, Andy Farnell wrote:
> 
> 
> I've attached again an example of a patch that demonstrates the
> practical difference between different one sample differentiators.
> 
> Try replacing [fexpr~ $x1 - $x1[-1]] in the water flow generator with 
> 
> 
> / \
> |  [z~]
> |  |
> [-~]
> |
> 
> which is fine.
> 
> Then try implementing the same with [rzero~ 1]
> 
> It sounds very different and I have not found a way to correct
> the accumulating DC error. Try the obvious [rzero~ 0.99999999]
> etc to hear that the behaviour is still not right.
> 
> Fundamentally, [z~] is a *very* useful primitive to have
> 
> 
> 
> On Fri, 25 Apr 2008 07:04:10 -0400
> Enrique Erne <enrique at netpd.org> wrote:
> 
> > IOhannes m zm?lnig wrote:
> > > Enrique Erne wrote:
> > >> IOhannes m zm?lnig wrote:
> > >>> Enrique Erne wrote:
> > >>>> or [biquad~ 0 0 0 1]
> > >>>>
> > >>>>
> > >>>> Miller Puckette wrote:
> > >>>>> I believe z~ is just rzero~ 0.
> > >>> no.
> > >>> both of them are equivalent to [z~ 1]
> > >>>
> > >>> you could also argue that [f] is just the same as [0(
> > >>> :-)
> > >> oups, yes ofcorse z~ 1.
> > >>
> > >> the output of 1 sample with rzero~ 0, z~ 1 and biquad~ 0 0 0 1 seems to
> > >> be slightly different. if one wants to be fuzzy about that :) maybe ome
> > >> rounding problem?
> > > 
> > > no, i don't see any rounding errors...
> > > 
> > >> and now i even couldn't do the delwrite/read with the subpatch :( :(
> > > 
> > > it's generally a good idea to tell [delwrite~] how much space it should
> > > allocate for the delayline. e.g. [delwrite~ abcd 1000] helped a lot...
> > > 
> > > 
> > > and [rzero~ 0] is not the same as [z~ 1].
> > > 
> > > 
> > > the output of [z~ 1] is y[n]=x[n-1]
> > > according to [rzero~]s help-patch it does the following:
> > > 
> > > y[n]=x[n]-a[n]*x[n-1]
> > > since you set a[n] to "0", you just get y[n]=x[n] :-(
> > > 
> > > to get [z~ 1], do something like
> > > 
> > > |
> > > +--+
> > > |  |
> > > |  [rzero~ 1]
> > > |  |
> > > [-~]
> > > |
> > 
> > 
> > thanks iohannes. it looks good now.
> > 
> > 
> > 
> > 
> > 
> 
> 
> -- 
> Use the source


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