Bruce Olson writes: | I had thought I had the simplest way to figure out sharps and flats | on the key signature from mode and keynote graphed on a .GIF on | my website. I was wrong. I found a much simpler way, as shown on a | new .GIF there, SFMODE2.GIF. Most will probably not need it at all, | the method is so simple and easy to do. | | Number letter notes in the order of sharps on the key signature | (F=1, C=2, G=3, D=4, A=5, E=6, B=7). If the keynote is sharp add | 7 (14 for double sharp), and if it's flat subtract 7 (-14 for | double flat). Subtract mode number (1-lydian, 2-ionian, 3 | mixolydian, 4-dorian, 5-aeolian, 6-phrygian, and 7- locrian) from | that note number and you get the number of sharps or flats you | put on the key signature. If the number is negative it's the | number of flats, and if it's positive it's the number of sharps.
This is the scheme that Michael Methfessel used in abc2ps. It works pretty well for the classical European key signatures. In my abc2ps clone, I added support for non-Western key signatures, so I had to half-eliminate this scheme. But it's still there, because it turns out to be convenient to write some key sigs with a classical mode modified by one or two accidentals. Thus I often write klezmer tunes in, say, D freygish as "K:Dphr^F". The code uses the above scheme for handling the "Dphr" part, giving a signature of -2. It then builds the list of accidentals from that and appends the ^F to the list. I'd guess that this numbering of classical key signatures has been discovered independently by any number of people. To subscribe/unsubscribe, point your browser to: http://www.tullochgorm.com/lists.html
