No, it's by all means not impossible,
just declare the var with init, as in...

afdb init 0
acmb delay asig+afdb, 0.5
afdb = acmb*0.5

Just note that if you need sample-by-sample
feedback, you'll ksmps=1 (you can use an UDO to
set a local ksmps.

Victor
----- Original Message ----- 
From: "Aaron Johnson" 
To: 
Sent: Saturday, April 19, 2008 5:02 PM
Subject: [Csnd] (un)controlled audio feedback


> Hi all,
>
> Just curious--on an analog circuit one can send a signal output back
> into it's own input. It seems that Csound is perhaps locked into a
> variable declaration style that would make simulating this
> impossible--i.e. one can't declare an output as an input unless the
> output has been previously declared. I was thinking that global
> variables and some trickery with 'init' might somehow make this
> possible, but maybe someone knows a better way to proceed. I recall as
> far as I remember that the DX7 emulation floating around uses phase
> modulation tricks and I think also uses global variables to simulate
> the DX7 algorithms that had feedback loops, but alas my 'Csound Book'
> is buried in a book box somewhere among about 20 boxes since
> rearranging our garage, so I can't confirm....or I should say, I don't
> want to go digging THAT mch!
>
> Anyway, has anyone tried to play around with chaotic signal paths by
> implementing 'feedback loops'?
>
> Best,
> Aaron Krister Johnson
>
>
> Send bugs reports to this list.
> To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe 
> csound"