HelpSource/Classes/Pgbrown.schelp

   1 class:: Pgbrown
   2 summary:: geometric brownian motion pattern
   3 related:: Classes/BrownNoise, Classes/Pbrown
   4 categories:: Streams-Patterns-Events>Patterns>Random
   5
   6 description::
   7
   8 Returns a stream that behaves like a geometric brownian motion.
   9
  10 ClassMethods::
  11
  12 method::new
  13
  14 argument::lo
  15 lower boundary of values.
  16
  17 argument::hi
  18 upper boundary of values.
  19
  20 argument::step
  21 maximum multiplication factor per step (omega) - the distribution is xrand2.
  22
  23 argument::length
  24 number of values produced.
  25
  26 Examples::
  27
  28 code::
  29 (
  30 var a, b;
  31 a = Pgbrown(0.0, 1.0, 0.2, inf);
  32 b = a.asStream;
  33 7.do({ b.next.postln; });
  34 )
  35
  36
  37 // sound example
  38 (
  39 SynthDef(\help_sinegrain,
  40         { arg out=0, freq=440, sustain=0.05;
  41                 var env;
  42                 env = EnvGen.kr(Env.perc(0.01, sustain, 0.2), doneAction:2);
  43                 Out.ar(out, SinOsc.ar(freq, 0, env))
  44         }).add;
  45 )
  46
  47 (
  48 var a;
  49 a = Pgbrown(1.0, 2.0, 0.1, inf).asStream;
  50 Routine({
  51         loop({
  52         Synth(\help_sinegrain, [\freq, a.next * 600 + 300]);
  53         0.02.wait;
  54         })
  55 }).play;
  56 )
  57
  58 // compare with normal brownian motion:
  59
  60 (
  61 var a;
  62 a = Pbrown(1.0, 2.0, 0.1, inf).asStream;
  63 Routine({
  64         loop({
  65                 Synth(\help_sinegrain, [\freq, a.next * 600 + 300]);
  66                 0.02.wait;
  67         })
  68 }).play;
  69 )
  70 ::