Computer-generated music is music composed by, or with the extensive aid of, a computer. Although any music which uses computers in its composition or realisation is computer-generated to some extent, the use of computers is now so widespread (in the editing of pop songs, for instance) that the phrase computer-generated music is generally used to mean a kind of music which could not have been created without the use of computers.
One of the first composers to write music with a computer was Iannis Xenakis. He wrote programs in the FORTRAN language which would automatically produce scores to be played by traditional musical instruments. An example is ST/48 of 1962. Later, composers such as Gottfried Michael Koenig had the computers generate the sounds of the composition as well as the score. Such music is still written today.
Since the invention of the MIDI system, some people have worked on programs which map MIDI notes to an algorithm and then can either output sounds or music through the computer's sound card or write an audio file for other programs to play.
Some of these programs are based on fractal geometry, and can map midi notes to specific fractals, or fractal equations. The resulting 'music' can be more like noise, or can sound quite familiar and pleasant. Although such programs are widely available and are sometimes seen as clever toys for the non-musician, some professional musicians have given them attention also.
Other programs can map the mathematical formula and constant to produce sequences of notes. An irrational number can give infinitely number sequence. Some people have the project to recompose this computer generated sequence into their original music composition.
Computers have also been used in an attempt to imitate the music of great composers of the past, such as Mozart. It is widely accepted that no computer has been able to produce music of the same quality as these composers, although they are able to imitate their style quite well.
See also: fractal music, trackers