Re: NR 1.2.3 Upbeats: confusing explanation of measurePosition

[David Kastrup]

Eluze <address@hidden> writes:

> Am 01.01.2013 00:36, schrieb David Kastrup:
>> Eluze <address@hidden> writes:
>>
>>> the sentence "The property measurePosition contains a rational number
>>> indicating …" is confusing indeed - where is a rational number?
>> "Moment" is generally misused in LilyPond for rationals since the C++
>> type "Rational" has no Scheme-accessible equivalent and the obvious
>> equivalent of Scheme rationals was not around at the time "Moment" was
>> concocted.
>>
> thanks for the rationale for the use of /rational /in this context - 
> it's far beyond my horizon

Yes, this would warrant cleaning up eventually.

> as a simple user I wish only to know which numbers I may use with the
> function ly:make-moment (to define the property measurePosition ) -
> without running into problemsof any kind!

Two integers (for numerator and denominator of a main moment fraction),
or four integers (the same with grace timing), or one rational (for the
main moment) or two rationals (for main and grace moment).

If you think that two integers and two rationals can't be told apart,
you'd be right, but denominators are always positive and grace timings
are always non-positive.

So basically everything that you'd think should work with ly:make-moment
will.  I'd prefer using rationals myself.

-- 
David Kastrup