Classes |

# Gendy2 : UGen : AbstractFunction : Object

Dynamic stochastic synthesis generator.
Source: Gendyn.sc

## Description

See Gendy1 help file for background. This variant of GENDYN is closer to that presented in Hoffmann, Peter. (2000) The New GENDYN Program. Computer Music Journal 24:2, pp 31-38.

NOTE: Random walk is of the amplitude and time delta, not the amp and time directly. The amplitude step random walk uses a Lehmer style number generator whose parameters are accessible.

SuperCollider implementation by Nick Collins

## Class Methods

### Gendy2.kr(ampdist: 1, durdist: 1, adparam: 1.0, ddparam: 1.0, minfreq: 20, maxfreq: 1000, ampscale: 0.5, durscale: 0.5, initCPs: 12, knum, a: 1.17, c: 0.31, mul: 1.0, add: 0.0)

#### Arguments:

ampdist

Choice of probability distribution for the next perturbation of the amplitude of a control point.

The distributions are (adapted from the GENDYN program in Formalized Music):

 0: LINEAR. 1: CAUCHY. 2: LOGIST. 3: HYPERBCOS. 4: ARCSINE. 5: EXPON. 6: SINUS.

Where the sinus (Xenakis' name) is in this implementation taken as sampling from a third party oscillator. See example below.

durdist

Choice of distribution for the perturbation of the current inter control point duration.

A parameter for the shape of the amplitude probability distribution, requires values in the range 0.0001 to 1 (there are safety checks in the code so don't worry too much if you want to modulate!).

ddparam

A parameter for the shape of the duration probability distribution, requires values in the range 0.0001 to 1.

minfreq

Minimum allowed frequency of oscillation for the Gendy1 oscillator, so gives the largest period the duration is allowed to take on.

maxfreq

Maximum allowed frequency of oscillation for the Gendy1 oscillator, so gives the smallest period the duration is allowed to take on.

ampscale

Normally 0.0 to 1.0, multiplier for the distribution's delta value for amplitude. An ampscale of 1.0 allows the full range of -1 to 1 for a change of amplitude.

durscale

Normally 0.0 to 1.0, multiplier for the distribution's delta value for duration. An ampscale of 1.0 allows the full range of -1 to 1 for a change of duration.

initCPs

Initialise the number of control points in the memory. Xenakis specifies 12. There would be this number of control points per cycle of the oscillator, though the oscillator's period will constantly change due to the duration distribution.

knum

Current number of utilised control points, allows modulation.

a

Parameter for Lehmer random number generator perturbed by Xenakis as in

c

Parameter for Lehmer random number generator perturbed by Xenakis.

mul

Output will be multiplied by this value.

This value will be added to the output.

#### Discussion:

All parameters can be modulated at control rate except for `initCPs` which is used only at initialisation.

## Examples

WARNING: if you have lots of CPs and you have fast frequencies, the CPU cost goes up a lot because a new CP move happens every sample!