The Composition

3. Algorithms

Alongside the precomposed parts of each movement are compositional processes, or algorithms: sets of instructions which encode musical behaviours, capable of recombining existing material and generating entirely new sequences of notes. These serve to massively increase the scope of potential patterns produced by Variable 4, and enable us to respond closely to the finer details of the meteorological conditions.

Algorithms: Markov chains and L-systems

On a movement-wide level, chance procedures are used to move between fragments according to sets of relationships designed at the compositional stage. The dynamic recombinations of these parts generate polyrhythms and composite tonal structures.

At the level of individual notes, a second set of algorithms are used to compose original note patterns. With structures drawn from mathematics, statistics and biology (above), these can continually produce sequences that are surprising even to the composers.