Re: enharmonic problem with \transpose - should we modify it?

[Janek Warchoł]

Hi,

2011/6/20 Benkő Pál <address@hidden>:
> hi Janek,
>
> well, it was nastier than I thought because of the current pitch 
> representation,
> so I haven't done it as a patch but a standalone hack; there's also a
> non-standard (E31) example.
>
> [...]
>
2011/6/21 Felipe Gonçalves Assis <address@hidden>:
> Enharmonicity is just an equivalence relation respecting the abelian
> group structure of intervals/transpositions. You can represent it by a
> quotient map or by its kernel.
>
> Your approach is representing the kernel, via its generators. This
> is complicated.
>
> A much simpler idea is to represent the quotient map, which is a
> particularly simple kind of function.
>
> [...]

Wow, thank you both!
I don't think i would be able to write this at so high level of
abstraction myself.
I think i understand your explanation and i can roughly see what is
going on in your code, except what the last argument(s) is (are) doing
- why is it #(ly:make-pitch 0 1 -1) (which equals deses' IIUC)? Is
this the "switch" which can be used to choose whether i want natural
or double-accidentaled notes?
I hope to be able to modify this function so it would read scale from
key signature. But before i'll do this, i'm afraid there is a problem:
should double-sharped notes be transformed into themselves and not
natural ones? Your examples contained the only one double-sharped note
which is transformed to a enharmonic equivalent (aisis -> ces), all
other double sharped notes remain the same - i.e. \enharmonizeMusic
\esMinor { gisis' } #et12-class #et12-octaves outputs gisis' -
shouldn't it output a'?

many thanks,
Janek