Algorithmic music has a long history, and can roughly be defined as music produced through the use of rigid, deterministic procedures - the opposite of improvisation. This allows for a great deal of music to be considered at least partially algorithmic, such as 17th and 18th century counterpoint, 20th century dodecaphonism and serialism, and more generally any genre requiring a certain compositional scheme. The artistic maverick John Cage frequently used algorithmic methods, including in determining the rhythms for the recently blogged about "Sonatas and Interludes", but Cage was also largely concerned with free creative impulse. Iannis Xenakis worked with concepts from areas as diverse as pure mathematics, physics, game theory, chance, and architecture in composing his influential sound works.
Mamoru Fujieda (1955 -) generates beautiful, otherworldly music from an even less likely source: living plants. Fujieda attached sensitive electrodes to the leaves of various plants, measuring their subtlely changing electric potentials. This data was then translated by the composer's algorithms into six collections of music, each in a different tuning system, written for traditional Asian and Western Medieval instruments. Patterns of Plants was released on Tzadik Records in 1997, featuring a live chamber ensemble performing the pieces. In 2008 this was followed by Patterns of Plants II, containing five new collections with different instrumentation, notably including violin. On both albums, the music is startlingly emotive and accessible, whether or not consideration is given to how it was made. In fact, most listeners would probably never suspect this was not "composed" by a human being in the ordinary sense of the word, a fact which is very easy to forget while listening. Fujieda's blind processes resulted in something starkly beautiful, balanced, organic, and very close to the human heart.