Re: fractions for make-moment

[Stefan Thomas]

Ok, sorry, I didn't see that rightly in the manual!

Thanks,

Stefan

2014/1/2 David Kastrup <address@hidden>

Stefan Thomas <address@hidden> writes:

> 2014/1/1 David Kastrup <address@hidden>
>> Stefan Thomas <address@hidden> writes:
>>
>> > Dear community,
>> > is it possible to use fractional or decimal numbers in ly:make-moment?
>>
>> Fractional: yes, decimal: no.
>>

>> > \once \override Beam #'grow-direction = #RIGHT \featherDurations
>> > #(ly:make-moment 1 1 )
>>
>> That does not look like either fractional or decimal.
>

> But if I would like to get an accelerando of 110 %, from 1 to 1.1, how
> could this be done?

#(ly:make-moment 11/10) looks rather fractional to me, and the
documentation for \featherDurations reads

       In the following example the eight 16th notes occupy exactly the
    same time as a half note, but the first note is one half as long as
    the last one, with the intermediate notes gradually lengthening.
    The first four 32nd notes gradually speed up, while the last four
    32nd notes are at a constant tempo.

         \override Beam.grow-direction = #LEFT
         \featherDurations #(ly:make-moment 2/1)
         { c16[ c c c c c c c] }
         \override Beam.grow-direction = #RIGHT
         \featherDurations #(ly:make-moment 2/3)
         { c32[ d e f] }
         % revert to non-feathered beams
         \override Beam.grow-direction = #'()
         { g32[ a b c] }

which also uses fractional values.  Now LilyPond does not use GUILE's
"arbitrary precision" rationals, so it will likely bomb out sooner than
strictly necessary when the numerators/denominators become uglily large,
see <URL:http://code.google.com/p/lilypond/issues/detail?id=3085>.
Other than that, you should be able to get along fine.

--
David Kastrup