I've been composing flute music, working at a high-energy virtuosic solo of 2-3 mins that I want to be one of the 'spotlit' moments of the hexagonal counterpoint. The basic method of construction is around the idea of 'letters' that permutate. The letters in this case are rhythmic patterns/cells each framed within one beat (so when they are strung together it is on the grid of a consistent pulse; however the rhythms mostly are syncopated so you hardly ever hear a downbeat, obscuring the sense of a consistent pulse).
I am aiming for a sense of permutation, circling, with a continual stream of 'letters'. I want to work with different kinds of streams, different kinds of 'random' from those that are information rich to those that might consist of 3 letters like the book with "MCV" repeated over and over...perhaps. (I am still looking to explore the decimal fractions idea that Marcus has introduced, perhaps within this context; I think of them as little seed pods).
How to set up the algorithm so it produces the right kind of music has been the challenge - that is the challenge of working algorithmically. I've moved away from the notion of pitch (note names) as 'letters' as it places too much importance on pitch and leads to a bland, characterless result.
I have mapped the rhythmic 'letters' to the numbers 1-8 (so instead of 22 there are just 8) and I am using the decimal places of pi to dictate the order (so a random 'permutation'). 9 at the moment is a space, and I like the spaces, but 0 is also a space (there aren't so many zeros early on) and the choice is whether to differentiate them as spaces (e.g. 'comma' and 'full stop') or to use zero as something else, perhaps as a kind of switch for something in the system to change. The digits of pi imitate randomness and are apparently infinite; it signifies the circle and the impossibility of circumference (and perhaps the impossibility of the circumference of the sphere that is the library/universe).
When I arrived at the rhythmic 'letters' (really 'syllables') I started off by using a short pitch series that cycled through strict permutations, each pitch assigned to one rhythmic attack so the distribution depended on the number of attacks in each rhythmic syllable; the drawback with this kind of pitch system for me is that the intervallic consistency (intervals, or the tune, remain constant while the pitch changes as you start one element later each time, transposing from the new starting point) and sense of a closed system starts to limit the music once you've gone around the cycle. For several years now I've used pseudo-random numbers up to 24 (i.e. giving the quarter tonal-chromatic complement) to generate pitch (water mountain was the first piece) and I then craft that 'found material' into phrases, pieces. That doesn't mean the pitch in my music is 'random' but that I don't start with pitch/notes at the centre of the universe I am creating. Likewise with this piece, I think the process of working with 'letters' has made me really consider what might be a 'letter', or 'grain' or unit of composition in my music. So I've switched to generating the pitch with random numbers, distributing them as they come across the attacks of the rhythms, to produce the raw material.
By adding pitch to the rhythms in this way you end up with an endless variety of differently-shaped 'syllables', despite the consistency of the rhythms, and the next layer of composing is to arrange the registration of the notes (i.e. which octave to put them in) and perhaps rearrange the ordering of the pitches or even change them occasionally, file them and sand them down in terms of the way they 'speak' on the instrument and to make them practical to perform. It's almost impossible to compose and interact with material in this way without hearing a 'line' emerging (like looking at a Pollock drip painting and seeing shapes) and the longer you work with the material the more likely it is to result in a process of selection, re-ordering or complete transformation; as well as recycling material inverted or transformed some other way.
Today I'm working with the idea of weaving in a second strand to the main flute line as described above, like weaving in another dimension, so that the flute is at times playing 2 lines, making it pretty busy. My plan is that gradually the second line takes over; the second line (at present) is faster, more erratic and continuous (perhaps there is a signification of infinity here), constructed from a different set of numbers: this time filtered random numbers so that at first it's sparse but later becomes more dense; pitch taken from the first line and inverted, etc. so that it is a kind of dirty mirror of the first. Anyway, let's see how that goes.