LotkaVolterra : MultiOutUGen : UGen : AbstractFunction : Object
Extension
ExtensionDescription
UGen implementing 4th order Runge-Kutta approximation of the Lotka and Volterras Predator-Prey model:
x' = x * (a - b * y)y' = y * (c * x - d)Implemented by Till Bovermann inspired by Gary William Flake's Book "The Computational Beauty of Nature". Implementation following on Lance Putnam's chaos UGens and MCLDs ChaosUGens.
Class Methods
LotkaVolterra.categories
LotkaVolterra.ar(freq: 22050, a: 1.5, b: 1.5, c: 0.5, d: 1.5, h: 0.05, xi: 1, yi: 0.2, mul: 1.0, add: 0.0)
Arguments:
| freq |
update frequency, best set to Nyquist frequency. To modulate tonal qualities, use |
| a |
meta-parameter, useful between 0 and 5; must not be negative. |
| b |
meta-parameter, useful between 0 and 5; must not be negative. |
| c |
meta-parameter, useful between 0 and 5; must not be negative. |
| d |
meta-parameter, useful between 0 and 5; must not be negative. |
| h |
step size for the approximation |
| xi |
initial value for x, resets the UGen when changed |
| yi |
initial value for y, resets the UGen when changed |
| mul |
multiply |
| add |
add |
LotkaVolterra.equation
returns
xxxxxxxxxxx' = x * (a - b * y)y' = y * (c * x - d)Inherited class methods
Instance Methods
Inherited instance methods
Examples
xxxxxxxxxx// scope signals, set graphics to 'xy' to see relations between predator (out 0) and prey (out 1){LotkaVolterra.ar(SampleRate.ir*0.5, \a.kr(1.5, 0.1), \b.kr(1.5, 0.1), \c.kr(0.5, 0.1), \d.kr(1.5, 0.1), h: \h.kr(0.01), xi: 0.1 + \tr.tr(1))}.scope;(Ndef(\lv).addSpec(\freq, [0.1, 24000, \exp]);Ndef(\lv).addSpec(\h, [0.01, 1, \exp]);Ndef(\lv).addSpec(\which, [0, 2, \lin]);Ndef(\lv).addSpec(\a, [0.01, 5, \lin]);Ndef(\lv).addSpec(\b, [0.01, 5, \lin]);Ndef(\lv).addSpec(\c, [0.01, 5, \lin]);Ndef(\lv).addSpec(\d, [0.01, 5, \lin]);Ndef(\lv, { LeakDC.ar( LotkaVolterra.ar(SampleRate.ir*0.5, \a.kr(1.5, 0.1), \b.kr(1.5, 0.1), \c.kr(0.5, 0.1), \d.kr(1.5, 0.1), h: \h.kr(0.01), xi: 0.1 + \tr.tr(1)) * 0.2 ).tanh + 1 * LFPar.ar([100, 150]);});)(Ndef(\lv, { Mix( LeakDC.ar( LotkaVolterra.ar(SampleRate.ir*0.5, a: {LFNoise2.ar(Rand(0.000174, 0.00174)).range(0.49, 0.5)}!3, b: \b.kr(1.5, 0.1), c: {LFNoise2.ar(Rand(0.000174, 0.00174)).range(2, 4)}!4, // \c.kr(0.5, 0.1), a: {LFNoise2.ar(Rand(0.000174, 0.00174)).range(0.4, 0.41)}!4, h: \h.kr(0.01).lag2(1) * [0.5, 1, 2, 4], xi: 0.1 + \tr.tr(1)) * 0.2 ) * [5, 3, 3, 1].normalizeSum; ).tanh});)Ndef(\lv).set(\tr, 0.1)Ndef(\lv).set(\a, 3.029850, \b, 4.094132, \c, 1.967217, \d, 2.295942);Ndef(\lv).scopeNdef(\lv).editlink::Classes/LotkaVolterra::