Classes (extension) | UGens > Filters

NL2 : UGen : AbstractFunction : Object

Arbitrary Non Linear Filter Equation

//SLUGens released under the GNU GPL as extensions for SuperCollider 3, by Nick Collins, 


Represents the arbitrary non-linear filter difference equation in the time domain:

y(n) = sum over terms of constant * product of x terms at individual powers * product of y terms at individual powers

This allows arbitrary crossterms in x and y, but is expensive to calculate.

Stability is definitely not guaranteed; most equations will quickly blow-up. See the guard arguments below. It is recommended that you stick to positive exponents for signals which are within -1 to 1, else explosion of values is inevitable.

(0.1)**(-1.26) //negative exponents cause blowup for smaller signals abs(sig) < 1.0

(1.1)**(2.26) //positive exponents cause blowup for larger signals abs(sig) > 1.0

You need to pass in the parameters via two buffers, of arbitrary size.

Class Methods, bufnum: 0, maxsizea: 10, maxsizeb: 10, guard1: 1000.0, guard2: 100.0, mul: 1.0, add: 0.0)



What do you want to filter?


A single buffer containing numcrossterms in the first index, then the specification of crossterms as (constant, num x terms, list of x index/exponent pairs, num y terms, list of y index/coefficient pairs). Buffer contents can be switched at run-time as longas this data format is strictly adherred to.


Maximum index stored for previous outputs


Maximum index stored for previous inputs


Watch out for blow-up and reset if necessary; this is the value of the maximum absolute output allowed.


Watch out for blow-up and reset if necessary; this is the value of the maximum absolute change of output allowed.

On discovering blow-up, filter output is set back to zero for all stored outputs, so that feedback cannot occur.

Inherited class methods

Instance Methods

Inherited instance methods