Curious behavior of "add#7"

[malcolmsailor]

music21 version

8.0.0a9

Problem summary

When using the add[] syntax with #7 to build RNs, we get the wrong bassnote.

Steps to reproduce

>>> from music21.roman import RomanNumeral as RN
>>> RN("IV[add#7]").bass() # expect F
<music21.pitch.Pitch E#4>

A similar thing happens with IV[add##7] and IV[add###7] but not with IV[add7]. And with iii[add##7] but not with iii[add#7]. Thus it seems to be an issue when the pitch-class of the raised 7th overlaps with the root.

Similar issue with

>>> RN("ii6[add#2]").bass()
<music21.pitch.Pitch E#4>

(I discovered this because believe it or not IV[add#7] occurs in the DCML ABC corpus)

[mscuthbert]

Confirmed, real bug. And can confirm it's not because of implied key, etc.

Strangely, this works.

In [13]: RN('II[add###6]', 'C').pitches
Out[13]: 
(<music21.pitch.Pitch D4>,
 <music21.pitch.Pitch F#4>,
 <music21.pitch.Pitch A4>,
 <music21.pitch.Pitch B###4>)

but this does not:

In [14]: RN('V[add###6]', 'C').pitches
Out[14]: 
(<music21.pitch.Pitch E###4>,
 <music21.pitch.Pitch G4>,
 <music21.pitch.Pitch B4>,
 <music21.pitch.Pitch D5>)

apparently it's taking the octave from the bass, so it matters if the letter name is "above" the bass letter name (where "above" is measured in order C,D,E,F,G,A,B).

Strangely, also, adding flat notes takes good care to ensure that the bass is the implied bass:

In [22]: RN('V6[addbb4]', 'C').pitches
Out[22]: 
(<music21.pitch.Pitch B4>,
 <music21.pitch.Pitch D5>,
 <music21.pitch.Pitch G5>,
 <music21.pitch.Pitch C--6>)

In [23]: RN('vi6[addbb4]', 'C').pitches
Out[23]: 
(<music21.pitch.Pitch C4>,
 <music21.pitch.Pitch D--4>,
 <music21.pitch.Pitch E4>,
 <music21.pitch.Pitch A4>)

In [24]: RN('vi6[addbbb4]', 'C').pitches
Out[24]: 
(<music21.pitch.Pitch C4>,
 <music21.pitch.Pitch E4>,
 <music21.pitch.Pitch A4>,
 <music21.pitch.Pitch D---5>)

In [25]: RN('V6[addbbb4]', 'C').pitches
Out[25]: 
(<music21.pitch.Pitch B4>,
 <music21.pitch.Pitch D5>,
 <music21.pitch.Pitch G5>,
 <music21.pitch.Pitch C---6>)

[mscuthbert]

Note that 'IV#7' works fine, which is probably how this chord should be written:

(<music21.pitch.Pitch F4>,
 <music21.pitch.Pitch A4>,
 <music21.pitch.Pitch C5>,
 <music21.pitch.Pitch E#5>)