"Brady Haran over at Numberphile has brought us an amazing experimental track based on Pi. Everything follows patterns of the irrational number, and the result is a mind-blowing progressive rock song. This expands upon the concept first tried with the Golden Ratio song. Notice the length of the video?"
BTW, How do you call the computer generated music field? I've been wondering for a while now if there has been any work in having completely computer generated theme music for games. Like for an FPS the computer will be reacting to speed of mouse movements, gun fire, visible enemies, lighting, general environment... And will write the notes and play appropriate music live instead of playing per-recorded tracks.
Of course, each game will need a musician to setup the initial parameters... A melody, genre constraints (scales, tempo), choice of instruments... Like queuing-in the double-bass at X beat that is triggered by gun-fire... Or intensifying the low drone in small dark corridors...It will also probably be pretty computationally intense taking up at least a processor core so I'm guess even if it's been studied for decades it couldn't have been done in games until quite recently...