MatrixGen

Generative musical composition in Csound: a toolkit for building families of Markov transition matrices from a few base matrices (interpolation, entropy relaxation, rotation), plus a composition engine that plays Markov chains over musical material using them. Demonstrated on the microtonal Markov material from [ocultado].

Structure

MatrixGen/
├── orc/                    UDOs (#include'd by every .csd)
│   ├── matrix_udos.orc         MatInterp, MatEntropy, MatRotate, BuildBiasedMatrix
│   ├── composition_udos.orc    NextMarkovState, PlayChain, PlayMetaChain
│   ├── export_udos.orc         ExportMatrixCsound (dump a matrix as paste-ready Csound text)
│   └── utilFunctions.orc       PrintMat, PrintMatHeat (print/debug helpers)
│
├── compositions/            the finished pieces (this is the result)
│   ├── pecaGestos.csd           full reimplementation of the Gestos Markov material
│   ├── GestosModelMatrizA.csd   reference transition matrix (BuildBiasedMatrix)
│   ├── GestosModelMatrizB.csd   Matrix A rotated (MatRotate) to privilege a different state
│   ├── GestosModelInterpolation.csd  morph A → B in 4 steps (MatInterp), one continuous chain
│   ├── GestosModelEntropy.csd   Matrix A relaxing toward uniform in 4 steps (MatEntropy)
│   └── audio/                   rendered .wav for each piece above (committed, ready to listen)
│
├── examples/                 generic engine demos + dev/test scripts (not the main result)
│   ├── peca_exemplo.csd         validated reference example (don't edit to experiment)
│   ├── experimentoComposicao.csd   playground for composing/experimenting (plays live, -odac)
│   ├── test_matrix_udos.csd     numeric tests for the matrix module
│   ├── test_biased_matrix.csd   tests for BuildBiasedMatrix + ExportMatrixCsound (round-trip check)
│   ├── test_composition_udos.csd  tests for PlayChain's 3 variant-selection modes
│   ├── testeManualMatrizes.csd  manual tests for MatInterp/MatEntropy/MatRotate
│   └── brincarComMatrizes.csd   playground for tuning BuildBiasedMatrix parameters
│
└── docs/
    ├── MANUAL.md                 how to use every UDO (signatures, examples, usage rules)
    ├── markov-csound-spec.md     original Gestos Markov specification (source material)
    └── referenciasDiversas.md    assorted references

Running

Requires Csound installed (csound --version to check) and a General MIDI soundfont. Files expect FluidR3_GM.sf2 at the repo root (not versioned here — freely redistributable, download it from e.g. https://member.keymusician.com/Member/FluidR3_GM/index.html and place it at ./FluidR3_GM.sf2).

cd MatrixGen/compositions
csound pecaGestos.csd

Always run csound from inside the folder that contains the .csd (compositions/ or examples/), not from the repo root. Csound resolves -o/output paths relative to the current working directory, not to the .csd file's own location — running from the wrong directory won't error, it'll just silently write the .wav somewhere unexpected.

The pieces in compositions/ render to audio/*.wav (already committed — you can just listen to those directly without installing Csound). peca_exemplo.csd and the test_*.csd files in examples/ also render to a file; experimentoComposicao.csd plays live (-odac).

Matrix module (orc/matrix_udos.orc)

N×N transition matrices are linear f-tables (row-major), with N set via a global variable (giN). Operations, all generalized for any N:

• MatInterp — interpolates between two matrices (linear or exponential).
• MatEntropy — pushes a matrix toward the uniform distribution (by degree).
• MatRotate — cyclically permutes states (two modes: full relabeling, or column-only/privilege shift).
• BuildBiasedMatrix — generates a matrix from affinity scores (softmax) instead of hand-typed probabilities.
• ExportMatrixCsound (orc/export_udos.orc) — writes a generated matrix out as ready-to-paste Csound source text.

See docs/MANUAL.md for full signatures and examples.

Composition engine (orc/composition_udos.orc)

Plays Markov chains over musical material (rhythm + pitch per state, with 3 variant-selection modes), with two modes: procedural (you write the calls) and meta-chain (a higher-level matrix decides on its own between different configurations). PlayChain calls can be chained with real continuity — even across a mid-piece change of transition matrix — which is what GestosModelInterpolation.csd/GestosModelEntropy.csd demonstrate. See docs/MANUAL.md for details.