Hello Csounders!

Let me introduce this new opcode:


nlalp
---------

aresult  nlalp    ainput, klfact, knfact [, istor] 

Passive non-linear allpass filter.

INITIALIZATION
istor    -  initial disposition of internal data space. Since filtering
            incorporates a feedback loop of previous output, the initial
            status of the storage space used is significant. A zero
value
            will clear the space; a non-zero value will allow previous
            information to remain. The default value is 0.

PERFORMANCE
klfact   -  linear part of the allpass filter coefficient.
knfact   -  nonlinear part of the allpass filter coefficient. If zero,
the
            filter will be a normal, yet adjustable allpass.

DESCRIPTION
This opcode performs a "passive", non-linear allpass filter after John
Pierce
& Scott Van Duyne (US Patent 5,703,313). "Passive" means that it is
energy-
conserving, which makes it useful in physical modeling instruments, like
waveguide meshes.


You find this description including an example at:
 http://www.harmonik.de/femc/download/new_jgops.txt 
and the source code at:
 http://www.harmonik.de/femc/download/new_jgops.cod 

Another example for its use is this gong-like instrument:
 http://www.harmonik.de/femc/download/gong.csd