[PD] www.pd-tutorial.com

[Frank Barknecht]

Hallo,
Kyle Klipowicz hat gesagt: // Kyle Klipowicz wrote:

> Frank, I'm curious about how you use list objects in composition. I'd love
> to see a little etude from you about that whenever you find the time. You
> always make such clear, concise, and fun instructional patches.

That's flattering so I guess I should give an example. ;)

[list] of course is useful for lots of stuff, e.g. as a general
container for messages (it's central for sssad in this regard), to
convert meta-messages to lists and back, etc.

In composition list-operations let you encapsulate many common tasks
in reusable abstractions. Johannes mentions LISP in his book, which
is the mother of all list-based composition software, but you can do
lots of stuff in Pd as well thanks to list.

As an example attached are abstractions that do four transformations
of little musical motives. The motives are stored as lists of numbers,
where each number represents a scale step. In the example a major
scale is used, but you can do 12-tone serialism as well and also apply
the transformations to rhythm lists etc. 

The four operations demonstrated are: 

- retrograde: play a motive backwards. That's a simple [list-rev] from
  the [list]-abs (included)

- transpose: add a number to each list-element. I used [list-map]
  here.

- inversion: That's a bit more complicated. Quoting Wikipedia:
    
  Inverted melodies
  
  When applied to melodies, the inversion of a given melody is the
  melody turned upside-down. For instance, if the original melody has a
  rising major third (see interval), the inverted melody has a falling
  major third (or perhaps more likely, in tonal music, a falling minor
  third, or even some other falling interval). Similarly, in twelve-tone
  technique, the inversion of the tone row is the so-called prime series
  turned upside-down.
  http://en.wikipedia.org/wiki/Inversion_(music)#Inverted_melodies

  In inversion.pd this is realised by walking through the list with
  list-map, taking the difference between the current element and the
  previous element, then substracting this from the current element.
  The first element in a list is treated specially as it has no
  previous element (it's just copied).
  
- retro-inversion: that's just a retrograde followed by an inversion.
  As we have abstractions for both not, just bundle them in another
  one.

list-compose.pd show all four operations in use to transform a little
motive.

(This text is available online as well at: 
http://footils.org/cms/weblog/2009/mar/18/using-list-composition-pd/
)

Ciao
-- 
 Frank Barknecht            Do You RjDj.me?          _ ______footils.org__
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