MacWorld 1999 January - Disc 2/Macworld (1999-01) (Disk 2).dmg/Serious Demos/Symbolic Composer 4.2/Environment/Projects/Questions & Answers/Q&A Programming Music/Defining tonalities

Lisp/Scheme | 1998-10-26 | 2KB | 46 lines

DEFINING TONALITIES

>I'm gradually discovering what's
>useful for me and making notes.  I wanted to do some things with
>tonalities--perhaps you can point me to the appropriate functions?  I want
>to create a tonality and then derive tonalities from that by performing
>various operations to it. The idea is, I could define a variable (the
>pitches or intervals of the original tonality) and reference that variable
>in create-tonality including various other operations. For example,
>increase each interval by one semitone (a five-tone whole-tone scale would
>become a five-tone scale with each step being 1.5 tones).  Then, by
>changing only the definition of the original variable, I could completely
>change the color of the whole score.  I thought something like
>(change-length) would be useful. Is there something like that I could use
>in this way?

You can use change-length or vector-round to scale a list of semitones
to a new range. When you convert the vector output to a list with
vector-to-list then you can use it to define a tonality.

(setq scale '(1 2 3 4 5 6))

(create-tonality normal scale)
(create-tonality scaled (vector-to-list (vector-round 1 12 scale)))

(activate-tonality (normal c 3))
--> ((c 3 c# 3 d 3 d# 3 e 3 f 3))

(activate-tonality (scaled c 3))
--> ((c 3 d 3 e 3 g 3 a 3 b 3))

using both for two different zones

(activate-tonality (normal c 3) (scaled c 3))
--> ((c 3 c# 3 d 3 d# 3 e 3 f 3) (c 3 d 3 e 3 g 3 a 3 b 3))

Or you might want to vector-mix another pattern to the scale

(create-tonality mixed (vector-to-list (vector-mix scale #(1 2 3))))

(vector-to-list (vector-mix scale #(1 2 3)))
--> (2 4 6 5 7 9)

(activate-tonality (mixed c 3))
--> ((c 3 d 3 e 3 d# 3 f 3 g 3))