Re: m7.5- transposed to sus#4 b3 ??

[Malte Meyn]

Am 12.11.19 um 09:56 schrieb Sandro Santilli:
> On Mon, Nov 11, 2019 at 10:08:07PM +0100, Thomas Morley wrote:
> > Am Mo., 11. Nov. 2019 um 21:38 Uhr schrieb Sandro Santilli <address@hidden>:
> > > I transcribed an A major song with this chords snippet:
> > >
> > >    ees:m7.5- | aes:7 | aes:m7.5- | des:7 |
> > >
> > > When transposing it to Eb major it is rendered as:
> > >
> > >    Bbbø | Ebb7 | Ebb7sus#4 b3 | Abb7
>
> > If you transpose the note eeses down an augmented 4th the note beseses results.
>
> I did not transpose eeses, but ees.
>
> > If you let the chords display in \new Staff you get a warning:
> > 2.18.2:
> > warning: Transposing eeses'' by ges makes alteration larger than double
>
> Indeed I do get that warning, but I was not transposing eeses ??
> Where does 'eeses' come from ?

It comes from the aes:m7.5- chord. LilyPond represents chords as pitches 
internally, so that is represented as <aes ces eeses ges>.

> > To circumvent, you could do \transpose a dis instead.
>
> Yup, this one fixes the warning and the weird rendering.
> Still uses double-alterations (double-sharps) but that's a
> separate issue (does lilypond have any support to automatically
> simpmlify those notes and/or chords?).

Vanilla LilyPond doesn’t have such an automatism but I think there are 
functions for that in the LilyPond Snippet Repository. But after writing 
down my findings below I’d go for the harmonically correct sharps even 
in the untransposed version.

> > Though, tbh I doubt chords based on ees, aes, des _in_ a-major are
> > correct at all.
> > Probably some modulation/key-change before? Or copy from a weird source?
>
> It's "The Shadow Of Your Smile" from the Real Book. I'm not sure
> what's going on there, harmonically.

You seem to use the Bb version of The Real Book (vol. 1):
        Eb-7b5 Ab7 Ab-7 Db7
The C version of The Real Book uses the harmonically more correct sharps:
        C#-7b5 F#7 F#-7 B7
The Bb version of The New Real Book (vol. 3) uses the sharp version:
        D#mi7(b5) G#7 G#mi7(b5) C#7

Note that you wrote a half diminished chord (m7b5) on Ab where the Real 
Book (at least the 5th edition) writes a minor 7 chord (m7).

If you have a close look at the melody in these measures (13–16) you’ll 
see that The Real Book in Bb uses the sharp version too:
        a'2. cis'4 bis2. a'4 gis1~ gis4 …