LilyPond Users:
I'm running into a scenario where it would be useful to subtract three 128th notes from a longer note's duration while having the longer note still appear as a single note in the printed score. This is useful when I have a printed score with three grace notes that I want to be played on the beat rather than before it, but the grace notes are understood differently from both the acciaccatura and the stereotypical "eighth-note with grace upper neighbor plus two sixteenths equals four sixteenths" type of appoggiatura commonly found in Classical-era music. Please do not stop reading this when I tell you that this may be a feature request, for it may also be a simple exercise in finding the right duration scale factor.
When the longer note is a whole note, the case is very simple. The duration is 1 * (1 - 3/128) = 1 * 125/128.
When the longer note is a half note, the case is more complicated. In my mind, the duration should be 2 * 61/64, but I don't know if that is correct.
Similarly, when the longer note is a quarter note, the duration should be 4 * 29/32.
One more example, this one using a dotted duration. The duration of a dotted quarter note is 3/8 of a measure, so the duration should be 4. * ((1/128)/(3/8)) = 4. * 1/48.
I still don't know if I am correct or not, but if I am, then it would ease my mind a bit.
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