start adding risset definitions; remove installer artifacts from git tree

Author: gesellkammer

.gitignore

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 build/
+*.exe

installer/win64/Output/Csound6-Plugins-Windows_x86_64-1.0.exe

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+# chuap
+
+## Abstract
+
+Simulates Chua's oscillator
+
+## Description
+
+`chuap` Simulates Chua's oscillator, an LRC oscillator with an active resistor, proved 
+capable of bifurcation and chaotic attractors, with k-rate control of circuit elements. 
+
+The oscillator can be driven into period bifurcation, and thus to chaos, because of the
+nonlinear response of the active resistor. 
+
+![](assets/chua-circuit.png)
+
+The circuit is described by a set of three ordinary differential equations called Chua's equations:
+
+
+      dI3      R0      1
+      --- =  - -- I3 - - V2
+      dt       L       L
+
+      dV2    1       G
+      --- = -- I3 - -- (V2 - V1)
+      dt    C2      C2
+
+      dV1    G              1
+      --- = -- (V2 - V1) - -- f(V1)
+      dt    C1             C1
+
+
+ where f() is a piecewise discontinuity simulating the active resistor:
+
+
+      f(V1) = Gb V1 + - (Ga - Gb)(|V1 + E| - |V1 - E|)
+    
+
+A solution of these equations `(I3,V2,V1)(t)` starting from an initial state `(I3,V2,V1)(0)` is called a 
+trajectory of Chua's oscillator. The Csound implementation is a difference equation simulation of 
+Chua's oscillator with Runge-Kutta integration. 
+
+
+!!! note
+
+	This algorithm uses internal non linear feedback loops which causes audio result to depend on 
+	the orchestra sampling rate. For example, if you develop a project with sr=48000Hz and if you 
+	want to produce an audio CD from it, you should record a file with sr=48000Hz and then downsample 
+	the file to 44100Hz
+
+!!! warning
+
+	Be careful! Some sets of parameters will produce amplitude spikes or positive feedback that could 
+	damage your speakers. 
+
+
+---------------------------
+
+## Syntax
+
+
+```csound
+aI3, aV2, aV1 chuap kL, kR0, kC2, kG, kGa, kGb, kE, kC1, iI3, iV2, iV1, ktime_step
+```
+    
+## Arguments
+
+
+* **iI3**: Initial current at G
+* **iV2**: Initial voltage at C2
+* **iV1**: Initial voltage at C1
+* **kR0**: Resistor R0 (R0 in the diagram)
+* **kC1**: Capacitor C1
+* **kL**: Inductor L (L1 in the diagram)
+* **kC2**: Capacitor C2
+* **kG**: Resistor G (part of the active resistor, R1 in the diagram). The G parameter 
+	is the time step, which is needed to get the same slope of the piecewise discontinuity 
+	from Ga and Gb for all sampling rates.
+* **kGa**: Resistor V (nonlinearity term of the active resistor, one of the R2's in the diagram)
+* **kGb**: Resistor V (nonlinearity term of the active resistor, one of the R2's in the diagram)
+* **kE**: Size of the piecewise discontinuity simulating the active resistor
+* **ktime_step** Delta time in the difference equation, can be used to more or less control pitch.
+
+## Output
+
+* **aI3**: ??
+* **aV2**: ??
+* **aV1**: ??
+
+
+## Execution Time
+
+* Performance
+
+## Examples
+
+
+```csound
+<CsoundSynthesizer>
+<CsOptions>
+; Select audio/midi flags here according to platform
+-odac     ;;;RT audio out
+;-iadc    ;;;uncomment -iadc if RT audio input is needed too
+; For Non-realtime ouput leave only the line below:
+; -o chuap.wav -W ;;; for file output any platform
+</CsOptions>
+<CsInstruments>
+
+sr     = 44100
+ksmps  = 32
+nchnls = 2
+0dbfs  = 1
+
+gibuzztable ftgen 1, 0, 16384, 10, 1
+
+instr 1	
+	
+    istep_size    =       p4
+    iL            =       p5
+    iR0           =       p6
+    iC2           =       p7
+    iG            =       p8
+    iGa           =       p9
+    iGb           =       p10
+    iE            =       p11
+    iC1           =       p12
+    iI3           =       p13
+    iV2           =       p14
+    iV1           =       p15
+
+    iattack       =       0.02
+    isustain      =       p3
+    irelease      =       0.02
+    p3            =       iattack + isustain + irelease
+    iscale        =       1.0
+    adamping      linseg  0.0, iattack, iscale, isustain, iscale, irelease, 0.0
+    aguide        buzz    0.5, 440, sr/440, gibuzztable
+    aI3, aV2, aV1 chuap   iL, iR0, iC2, iG, iGa, iGb, iE, iC1, iI3, iV2, iV1, istep_size 
+    asignal       balance aV2, aguide
+
+    outs asignal*adamping, asignal*adamping
+endin
+
+</CsInstruments>
+<CsScore> 
+;        Adapted from ABC++ MATLAB example data.
+//             time_step      kL           kR0         kC2              kG            kGa           kGb          kE          kC1           iI3                     iV2                     iV1
+; torus attractor ( gallery of attractors ) 
+i 1 0 20       .1            -0.00707925   0.00001647  100              1             -.99955324    -1.00028375  1          -.00222159     -2.36201596260071       3.08917625807226e-03    3.87075614929199   
+; heteroclinic orbit
+i 1 + 20       .425           1.3506168    0           -4.50746268737  -1             2.4924        .93          1           1             -22.28662665            .009506608              -22.2861576            
+; periodic attractor (torus breakdown route)
+i 1 + 20       .05            0.00667      0.000651    10              -1             .856          1.1          1           .06           -20.200590133667        .172539323568344        -4.07686233520508      
+; torus attractor (torus breakdown route)'
+i 1 + 20       0.05           0.00667      0.000651    10              -1             0.856         1.1          1           0.1            21.12496758             0.03001749              0.515828669            
+
+</CsScore>
+</CsoundSynthesizer>
+```
+
+## See also
+
+* [crackle](crackle.md)
+* [standardchaos](standardchaos.md)
+* [durst2](https://csound.com/docs/manual/dust2.html)
+
+
+## Credits
+
+* Author of MATLAB simulation: James Patrick McEvoy MATLAB Adventures in Bifurcations and Chaos (ABC++)
+* Author of Csound port: Michael Gogins, michael dot gogins at gmail dot com
+* New in Csound version 5.09

risset/chua/doc/assets/chua_circuit.png

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+{
+  "name": "chua",
+  "version": "0.1.0",
+  "opcodes": [
+    "chuap"
+  ],
+  "short_description": "Implementation of a Chua oscillator",
+  "long_description": "Opcodes simulating Chua's oscillator, proved capable of bifurcation and chaotic attractors",
+  "csound_version": "6.17",
+  "author": "Michael Gogins",
+  "email": "michael.gogins@gmail.com",
+  "license": "GPLv3",
+  "repository": "https://github.com/csound/plugins",
+  "binaries": {
+    "linux": {
+      "url": "https://github.com/csound-plugins/csound-externals/releases/v${version}/csound-externals--linux.zip",
+      "extractpath": "libchua.so",
+      "build_platform": "Ubuntu-latest"
+    },
+    "macos": {
+      "url": "https://github.com/csound-plugins/csound-externals/releases/v${version}/csound-externals--linux.zip",
+      "extractpath": "libchua.dylib",
+      "build_platform": "macos-latest"
+    }
+  }
+}