Re: a:4 chord

[Luc Saffre]

Thanks, Brett.

To summarize for myself, and maybe some documentation maintainer wants
to integrate that somewhere:

If I'm encoding chords from a previously published score, and there is a
"C4", then (1) I try to find out what they really meant, and (2)
depending on that:

If they meant...        Then I code...
----------------------  --------------
c-e-f-g (added 4th)     c:add4
c-f-g (suspended 4th)   c:sus4
inverted power chord    (this was too confusing for me, so I can't
                        summarize, but anyway I won't have that case.

And if I want one of those renderd as the short "C4" form, then I use an
exception. For example if I want c:add4 to be rendered as c^4, then I do
something like:

  chExceptionMusic = {
    <c e f g>4-\markup { \super "4" }
  }
  % Convert music to list and prepend to existing exceptions.
  chExceptions = #( append
    ( sequential-music-to-chord-exceptions chExceptionMusic #t)
    ignatzekExceptions)

And coding the short form "c:4" into the LP source is actually a bad
idea because that yields c-e-f, which doesn't actually fit any of the
above interpretations of "C4".

Luc


On 19.03.2009 9:26, Brett Duncan wrote:
> Luc Saffre wrote:
>> Can somebody explain what's the difference between printing "A^sus4" and
>> "A^4"? I had only basic music education but am helping with publishing a
>> songbook using Lilypond, and I thought that the difference is not
>> important. But now I'm afraid I'm wrong and that I'll have to check some
>> songs again. Is that right?
>
> The short answer is, it depends on who you are talking to!
>
> If you look at the Dolmetsch Online for example
> (http://www.dolmetsch.com/musictheory17.htm), you'll find there that C4
> means a C major triad with an added 4th (C-E-F-G). I know several jazz
> musos who interpret it exactly this way.
>
> OTOH, others interpret C4 as a suspended 4th (C-F-G).
>
> Just to add to the confusion, some rock guitarists use this notation to
> indicate an inversion of the classic "power" chord, which is really just
>  an interval of a 5th (e.g. the C5 power chord is just C-G). A C4 in
> this case is just an inversion of an F5 power chord, with just C-F.
>
> Personally, I prefer to avoid the potential confusion by not using the
> notation C4 at all, and use Csus4 or Cadd4 to clear what I mean. (I
> don't have to myself  the power chords, since they don't get used that
> often in jazz ;-).
>
> One other thing to be aware of - if you put C:4 into LP, the chord you
> get is C-E-F, which doesn't actually fit any of the above
> interpretations of "C4". So if you want the power chord, for example,
> you need to enter c:4^3 to remove the 3rd.
>
> HTH,
> Brett
>