Denis Lorrain

Construction 041

Toccata and Fugue

Algorithmic composition for MIDI piano

(2012, total duration: *ca.* 7'15")

Programme Note

   This Construction originates in a graphical example I have used in various circumstances during my teaching activities involving the LISP programming language. It consists in simulating a vegetal growth process, more specifically that of a climbing plant such as liana or, even more precisely, ivy (*Hedera*), honeysuckle (*Caprifoliacea*), jasmine (*Oleacea*), etc. Of course, the pedagogical point behind this demonstration is to illustrate a recursive fractal process deformed by a certain degree of controlled randomness. While commenting this graphical example, I had often mentioned the possibility of translating it analogically into a melodic—melismatic—process. But only a few years later did I actually realise this and use it concretely in the present result.

   While commenting this graphical example, I had often mentioned the possibility of translating it analogically into a melodic — melismatic — process. But only a few years later did I actually realise this and use it concretely with the present result.

   To gather the elements, or "voices", composing these two short pieces, I resorted to careful settings of the parameters of the algorithm. Moreover, the process being somewhat unpredictable by definition, I had to perform, in nearly all cases, a pragmatic selection among numerous trials. As in my other Constructions, the selected elements were then freely grouped and assembled.

   The inspiration behind the two movements is of a very fast Toccata (Prelude) followed by a slower Fugue. Of course, this must be understood at the level of global gestures, and in particular not of a "real" fugue.

DLO

Karlsruhe

November 2012