Re: 13th chord?

[Thomas Morley]

2017-02-26 1:53 GMT+01:00 David Kastrup <address@hidden>:
> Thomas Morley <address@hidden> writes:
>
>> Well,
>> the printed output of
>>
>> m =
>> \chordmode {
>>     <c' e' g' bes' d'' f'' a''>
>>     c:11.13
>>     %% unnecessarily verbose:
>>     c:1.3.5.7.9.11.13
>> }
>>
>> mII =
>> \chordmode {
>>     <c' e' g' bes' d''  a''>
>>     c:13
>>     %% unnecessarily verbose:
>>     c:1.3.5.7.9.13
>> }
>>
>> <<
>>   \new ChordNames { \m \mII }
>>   \new Staff { \m \mII }
>>>>
>>
>> looks perfectly fine to me.
>
> The printed output for all of the first is C13 (so we have c:11.13 ->
> C13).  The printed output for all of the second is C9 13 (so we have
> c:13 -> C9 13).
>
> As a user interface, that's peculiar.  The question is why we have
> different defaults for input and output of chords.

The most common use-case for a 13-chord is to _omit_ the 11th, so we
make an exception for it. And it's even documented:

NR Extended and altered chords
"Since an unaltered 11 does not sound good when combined with an
unaltered 13, the 11 is removed from a :13 chord (unless it is added
explicitly)."

and

NR A.2 Common chord modifiers

Dominant thirteenth    Dominant ninth, major thirteenth c1:13 <image>
Dominant thirteenth    Dominant eleventh, major thirteenth    13.11
c1:13.11 <image>


>
>> Obviously it's _me_ not understanding the issue.
>
> Does this make it clearer?

You explained the issue sufficiently, thanks!

Though, as said before, it's a design-decision and ofcourse we could
do it the other way round, i.e.:
c:13 -> c 13
c:13^11 -> c 9 13
but no bug.

Cheers,
  Harm