Issue 121 in mingus: Subtonic issues

[min...@googlecode.com]

Status: New
Owner: ----
Labels: Type-Defect Priority-Medium

New issue 121 by andreas....@gmail.com: Subtonic issues
http://code.google.com/p/mingus/issues/detail?id=121

In chords.py I have two question marks

1. Shouldn't vii7 return subtonic7?

def vii7(key):
return subtonic(key)

def VII7(key):
return subtonic7(key)

2. Isn't subtonic being confused with leading tone?
subtonic7("C") => ['B', 'D', 'F', 'A']
Shouldn't it be a whole step below tonic and thus ['Bb','D','F','Gb']?

http://books.google.com/books?id=bJdrYYBJFnoC&pg=PA157&lpg=PA157&dq=subtonic+triad&source=bl&ots=k_bo1XKhKt&sig=saXOomaRLG1RjfkyoJfql_ZF1hI&hl=en&sa=X&ei=MTM1UfChO-rr0QG4xoDgBg&ved=0CGIQ6AEwCA#v=onepage&q=subtonic%20triad&f=false

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[min...@googlecode.com]

Comment #1 on issue 121 by OrtalisM...@gmail.com: Subtonic issues
http://code.google.com/p/mingus/issues/detail?id=121

This change in chords.py will fix the issue:

def subtonic(key):
"""Return the subtonic chord in key.

Example:
>>> subtonic('C')
['B', 'D', 'F']
"""
return triads(intervals.minor_third(key))[4]

def subtonic7(key):
"""Return the subtonic seventh chord in key."""
return sevenths(intervals.minor_third(key))[4]

Attachments:
chords.py 36.7 KB

[min...@googlecode.com]

Comment #2 on issue 121 by OrtalisM...@gmail.com: Subtonic issues
http://code.google.com/p/mingus/issues/detail?id=121

Oh, I hadn't added a leading_tone() or lead_tone7() functions before, these
should work. If leading_tone7() is passed a minor key (lowercase) it will
give a diminished 7th chord and if it is passed a major key it will give a
half diminished 7th, so I believe the is how it should be.

I tried to fix the corresponding roman numerical chord functions too, but
they might not be correct. I would have thought that lowercase roman
numeral should give the minor (or diminished) chord (depending on the
degree) while uppercase should give major, but this is not the convention
in the file.

Attachments:
chords.py 37.3 KB