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## Re: feathered beam calculations

 From: Michael Gerdau Subject: Re: feathered beam calculations Date: Wed, 19 Dec 2018 11:39:01 +0100 (CET)

```> How does one  calculate the extra numbers needing to be for the spacing OUT
> of notes as the feather speed up slow down. They always look spaced tight
> together as real notes just beamed differently.  When you engrave a feather
> beam measure should youy first figure out how many notes you want (or stems)
> in the feathers or begin by finding how many beats they all should take up?
> I cannot find this out anywhere. And finally how to ensure always the
> spacing out of notes automatically according to the slow down speed up ramp
> of feathers. Thank you.

I have difficulties to grasp what you actually want to know or do not
understand.

To me it sounds as if you think feathered beams do somehow (magically) solve
rallentando/accellerando problems for you. [I don't think that is the case
though]

So here I go again with some obvious stuff to make sure we are talking about
the same.

First thing you have to answer for yourself is:
What do I need feathered beams for?
The answer should be something along the line "to visually notate an
accellerando or rallentando".
Assuming that's your answer then you should have a rough idea as to how
strongly you wish to change the timing, as in double/halve the speed, adding
50% to it etc. pp.
Doubling the speed would mean you'd have to issue
\featherDurations #(ly:make-moment 1/2)
Halving the speed would mean
\featherDurations #(ly:make-moment 2/1)
\featherDurations #(ly:make-moment 2/3)
and so on.
You come to these numbers by dividing the metronom marks at the beginning of
your section through the metronom mark at the end of it.

Basically that's it. No magic. You as the composer have to know what you want
and you should be able to write it down simply by giving metronom marks along
the way. Once you can do that you could use feathered beams to visually show it.

All of the above is also documented in the notation manual under
http://lilypond.org/doc/v2.19/Documentation/notation-big-page#feathered-beams
Maybe you could try to explain what actually it is that you don't understand.

BTW:
I've never come across feathered beams in any of the music I've performed so
far. From a performers PoV I'm not yet convinced they do help alot, but that
may be biased because I never used them. Bach, Mozart, Beethoven, Tchaikowski,
Reger (add which classic composer you miss) did not use them. They wrote it
differently (which is not to say they are useless, only not necessarily
required to write proper music ;)

Kind regards,
Michael
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