View source for D = A220

{{Thumb|DD115438|[[DD115438]]}}

[[D = A220]] is what we call an unidentified piece of music by Delia for which there is an unconventional mathematical score in her papers.

=Analysis=
The piece consists of six bars called A to F, each of which is contructed from three or four of eight musical phrases, [1] to [8], which are played on six notes, bottom C, D, Eb, A, Bb and top C, transposed so that the D is a 220Hz, the A below middle C. The phrases are:
<PRE>
[1] A
[2] A D
[3] A Bb A D
[4] A Bb A Eb
[5] A Bb A Eb D
[6] A Bb A Eb D C,
[7] A Bb A C' A
[8] A Bb A C' A Eb D C,
</PRE>
where "<TT>C,</TT>" means the bottom C and "<TT>C'</TT>" the top one, and the bars are composed of the phrases:
<PRE>
A: [1] [2] [3] [5]
B: [2] [4] [6]
C: [2] [3] [7] [2]
D: [2] [3] [4] [3]
E: [2] [5] [3]
F: [2] [7] [8]
</PRE>

The note lengths within each phrase, written in a circle above each note, are different each time the phrase is used, hence so is the length of each phrase, written in a circle above each phrase's bracket. The cumulative running time of the piece is written under the stave, for a total of 6 minutes and 50 seconds. 

The table in the bottom right corner gives all the multiples of 2.6 seconds from 1 to 42, so presumably that is the length of a note of duration (1).

The matrix above left of it gives the duration of each phrase when it is used in a particular bar and is derived from the score, adding no extra information.

This information is sufficient to reconstruct the piece.

=Score=
[[Image:DisA220.pdf|thumb|right]]
Here is the typeset score in four formats:
* [[:File:DisA220.txt|the LilyPond source file]]
* the typeset score as a PDF (right)
* [[:File:DisA220.midi|a MIDI file]] that you can [[Media:DisA220.midi|listen to]]
* An audio file of the MIDI file played on a cheesy electric piano
{{Play|DisA220}}

[[Category:Piece]]
[[Category:Score]]