This describes the process by which I composed "Irrational Thoughts", using the digits of pi.

Overview: I obtained a file with 100,000 digits of pi, and wrote a program in KeyKit which read it and used the individual digits (in a variety of ways) to drive an algorithm that generated a MIDI file. I used this to control an Access Virus synth for the sound-making, and used Sonar for recording, effects, and mixing.

Algorithm: piscan() scans the digits of pi and uses them to determine all note attributes (pitch, duration, etc). piscan() also uses the digits pi to selectively repeat sub-sections of the generated result. piscan() is used 6 times (with starting-offsets controlled by the digits of pi), and the results were overlaid. The first 5 digits of pi were used to control transposing of 5 sections of the piece.

Source code: see irrational.k

Tim Thompson - tjt-microsound@nosuch.com