Re: A twelve tone matrix engraver

[David Kastrup]

Caio Giovaneti de Barros <address@hidden> writes:

> On 02-01-2016 16:18, David Kastrup wrote:
>> It might also be worth taking a look at the facilities provided by
>> issue 4702
>> <URL:http://sourceforge.net/p/testlilyissues/issues/4702/> to see
>> how (or whether) they would have helped here. 
> Do you think you could write some small example of what those
> functions do? I didn't understand how they are used. One thing that I
> really wanted is an automatic way for the software to decide what
> notes should be flat and what should be sharp, even if it's not
> perfect. Currently my code only outputs sharps and to be honest this
> is not very natural to read (pun intended).

\version "2.19.35"

#(define semi->pitch
   (make-semitone->pitch (music-pitches #{ c cis d es e f fis g gis a bes b 
#})))

{ #@(map (lambda (s) #{ $(semi->pitch s) 2 #})
         (iota 37 (ly:pitch-semitones #{ g #}))) }

% That's usually close to C Major/A Minor, let's try something more
% befitting Fis Major/Dis Minor

#(define femi->pitch (shift-semitone->pitch #{ fis #} semi->pitch))

{ #@(map (lambda (s) #{ $(femi->pitch s) 2 #})
         (iota 37 (ly:pitch-semitones #{ g #}))) }

Note that make-semitone->pitch is a comparatively expensive call so it
makes sense to store the result, here semi->pitch and reuse it.
shift-semitone->pitch is quite cheap in contrast, so storing femi->pitch
is done more to make things more readable rather than out of efficiency
reasons.

-- 
David Kastrup