Re: feathered beam calculations

[Reggie]

Aaron Hill wrote
> This means your score really should be bar check clean *before* you ever 
> use \featherDurations. 
> 
> At the end of the day, there is no real need to use any math for the 
> \featherDurations moment.  Any positive rational less than one will 
> produce an accelerando, while fractions greater than one generate a 
> ritardando.  The best thing to do is to listen to the MIDI output and 
> determine if it sounds right to your ear.
> 
> I said earlier we would talk about bar checks *within* the feathered 
> sequence of notes.  Consider the following addition to our example:
> 
>      << { r64 \featherDurations #(ly:make-moment 2/1)
>               { c32*127/14[ d e f g a | b] } }
>         { r64 \featherDurations #(ly:make-moment 2/1)
>               { c32*63/12[ d e f g a] } | b1 }
>         { r64 { c64 d32 e16 f8 g4 a2 } | b1 } >>
> 
> You'll see that the 'b' is included within the beamed notes.  Because we 
> now have seven notes covering the period of two measures less one 64th, 
> we had to adjust our scaling fraction to 127/14.  However, what is most 
> important is that \featherDurations fixes the timing of the notes to 
> allow the inside bar check to pass.  Omit it, and you'll see that the 
> bar check fails.  But also try changing the 2/1 moment to anything else, 
> and the bar check will also fail.
> 
> What we have here is a very fragile element in the score that can be 
> easily avoided by never requiring any note (apart from the first) within 
> a feathered sequence to align to anything else.  The final 'b' above 
> should properly be outside the feathered sequence (or possibly start a 
> new sequence of its own).  In this way, the math to ensure all of the 
> sequences have the right lengths can be done completely independent of 
> \featherDurations.
> 
> Hopefully some of this will be helpful.
> 
> -- Aaron Hill
> 
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The fractions do NOT always  accelerando, while fractions greater than one
generate a 
ritardando as intended. That is why I began this mess in the first place :))




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