Re: Issue 2142 in lilypond: accidental right-padding should depend on the tightness of music

[lilypond]

Comment #2 on issue 2142 by address@hidden: accidental right-padding  
should depend on the tightness of music
http://code.google.com/p/lilypond/issues/detail?id=2142

Welcome to my world of pain.

I toyed around with ideas like this in my summer-of-lily but gave up  
because of the following reason :

In LilyPond, springs and rods are calculated based on the distances between  
paper columns, which requires knowing the columns' horizontal skylines.   
What you're suggesting are having conditional skylines that can change in  
different spacing situations.  This means that a given spring-and-rod  
problem will need to be solved 2**n times, where n is the number of  
conditional spacing variations that could happen in it.  If there are 10ish  
conditional variations (meaning accidentals) per line, you're looking at  
compilation times that last well into the end of Western music (if not  
earth).

I've suggested several times that linear programming & the simplex method  
(or a commensurately effective solver) could be the solution to these woes,  
but Han-Wen told me that in the early days of LilyPond this is how things  
were done & compilation times got outta hand.  I'd be interested in seeing  
how linear programming w/ 10000ish variables would fare on a modern  
computer - if it's hackable, it may be worth looking into this.