Stochastic & Mathematical Composition
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What is Stochastic Lab?
An algorithmic composition instrument inspired by Iannis Xenakis's stochastic methods — probability distributions, Markov chains, and statistical density generate melodies, rhythms, clusters, clouds, pointillistic textures, and structured sequences, which you can freeze, edit, and arrange into a finished piece.
What are Layers?
Each layer is its own independent generator (mode, distribution, register, etc.) that plays simultaneously with the others. Layers share one global tempo but keep their own loop length, so they drift in and out of phase against each other over time instead of always resetting together.
What's the difference between synthesis and Orchestral/Sampled Sounds?
By default the app plays real sampled instruments — orchestral strings (high and low register, chosen explicitly or left to rotate), winds, brass, and a real percussion kit (choose exactly which of its 8 sounds are in play), with glissando and tremolo. Turn the "Orchestral/Sampled Sounds" toggle off to switch that layer to pure oscillator synthesis (and an electronic percussion kit for rhythm mode) instead. Only the parameters that actually affect the current mode are shown, so the panel never shows a control that would silently do nothing.
Can I edit the notes directly?
Yes — tap the expand icon on the score to edit right there: a piano roll or the same Xenakis-style graphic notation, your choice, with pinch-free zoom (horizontal and vertical), dragging notes, and toggling glissando/tremolo per note. A live on-screen keyboard lets you play notes straight into a track by hand, recorded in sync with playback. Tap Save any time, or Freeze a live generation into a new editable, multi-track composition in your Library.
What is Full Score?
A fullscreen view of the graphic score that switches between any single layer and the combined arrangement, useful for reading the whole piece or exporting it as an image (the full combined score, or one "particella" image per layer).
What is Song mode?
Song mode lets you sequence several saved compositions end to end, repeat each one a set number of times, reorder them, and play or export the whole arrangement as one piece.
Can I export my composition?
Yes — export audio (WAV) or a Standard MIDI File, either as one mixed file or as separate stems (one file per layer/track), for a single section, or for a whole Song arrangement. MIDI exports carry real pitch-bend data for glissando and any scale that doesn't land on standard 12-tone tuning. You can also export the generative score itself as a graphic-score image.
Does Stochastic Lab work inside GarageBand, Logic, or AUM?
Yes — it includes an Audio Unit (AUv3) instrument plugin that runs the same generative engine live inside a compatible host, with mode, density, distribution, tempo, and instrument choice exposed as automatable parameters, so you can record its output as a MIDI performance on your own track.
What's in the Theory tab?
Short articles on Xenakis's life and methods — stochastic music, probability distributions, density and sound masses, the UPIC system, his major works, and the relationship between mathematics and composition — several with interactive widgets you can sample and hear.
Stochastic Lab does not collect any personal data, does not require an account, and does not connect to the internet. All generation, audio synthesis/sampling, and file export happen entirely on-device. Saved compositions, presets, and songs are stored locally on your device only.
Stochastic Lab is an independent educational project inspired by Iannis Xenakis's compositional methods. It is not affiliated with, endorsed by, or produced in association with the Xenakis estate. The Theory tab covers publicly documented biographical facts and generally known theoretical concepts; it does not reproduce his copyrighted musical works or writings.