Module:MOS
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- This module primarily serves as a library for other modules and has no corresponding template.
This module provides functions for working with MOS scales in Lua code.
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No function descriptions were provided. The Lua code may have further information.
local rat = require('Module:Rational')
local seq = require('Module:Sequence')
local et = require('Module:ET')
local p = {}
-- create a MOS structure (nL)L (ns)s <equave>
function p.new(nL, ns, equave)
local nL = nL or 5
local ns = ns or 2
local equave = equave or 2
return { nL = nL, ns = ns, equave = equave }
end
function round(num, numDecimalPlaces)
local mult = 10^(numDecimalPlaces or 0)
return math.floor(num * mult + 0.5) / mult
end
-- parse a MOS structure
function p.parse(unparsed)
local nL, ns, equave = unparsed:match('^(%d+)[Ll]%s*(%d+)[Ss]%s*(.*)$')
nL = tonumber(nL)
ns = tonumber(ns)
equave = equave:match('^%((.*)-equivalent%)$') or equave:match('^<(.*)>$') '2/1' -- Assumes this is a rational ratio written a/b
equave = rat.parse(equave)
if nL == nil or ns == nil or equave == nil then
return nil
end
return p.new(nL, ns, equave)
end
-- construct a string representation for a MOS structure
function p.as_string(mos)
local suffix = ''
if not rat.eq(mos.equave, 2) then
suffix = '<' .. rat.as_ratio(mos.equave):lower() .. '>'
end
return '' .. mos.nL .. 'L ' .. mos.ns .. 's' .. suffix
end
-- Find the brightest mode of a mos.
-- We go back to the root of the scale tree, then progressively construct descendants.
function p.brightest_mode(mos)
local nL = mos.nL
local ns = mos.ns
local d = rat.gcd(nL, ns)
if d > 1 then -- use single period mos, with period as new equave
nL = round(nL/d)
ns = round(ns/d)
end
current_nL, current_ns = nL, ns
local path_to_root = {}
while current_nL > 1 or current_ns > 1 do -- while current mos is not 1L 1s<equave>, record current mos and go up to parent
assert(current_nL ~= current_ns, "current_nL == current_ns")
table.insert(path_to_root, {[1] = current_nL, [2] = current_ns})
current_nL, current_ns = math.min(current_nL, current_ns), math.max(current_nL, current_ns)-math.min(current_nL, current_ns) -- parent's nL and ns
end
assert(current_nL == 1 and current_ns == 1, "Did not reach root successfully")
local len_of_path = table.getn(path_to_root)
assert(len_of_path >= 0)
local result = 'Ls'
for j = len_of_path, 1, -1 do
local child_nL, child_ns = path_to_root[j][1], path_to_root[j][2]
if child_nL > child_ns then -- this will give darkest mode, reverse for brightest mode
result = string.gsub(result, '[Ls]', {['L'] = 'sL', ['s'] = 'L'})
result = string.reverse(result)
else
result = string.gsub(result, '[Ls]', {['L'] = 'Ls', ['s'] = 's'})
end
end
return string.rep(result, d)
end
function p.bright_gen(mos) -- Compute the abstract, equave-agnostic bright generator as a "vector" of L and s steps.
local nL = mos.nL
local ns = mos.ns
local d = rat.gcd(nL, ns)
if d > 1 then -- use single period mos, with period as new equave
nL = round(nL/d)
ns = round(ns/d)
end
current_nL, current_ns = nL, ns
local path_to_root = {}
while current_nL > 1 or current_ns > 1 do -- while current mos is not 1L 1s, record current mos and go up to parent
assert(current_nL ~= current_ns, "current_nL == current_ns")
table.insert(path_to_root, {[1] = current_nL, [2] = current_ns})
current_nL, current_ns = math.min(current_nL, current_ns), math.max(current_nL, current_ns)-math.min(current_nL, current_ns)
end
local len_of_path = table.getn(path_to_root)
local result = {['L'] = 1, ['s'] = 0} -- Record the previous bright gen; the bright gen of 1L 1s is 1L + 0s.
for j = len_of_path, 1, -1 do
local child_nL, child_ns = path_to_root[j][1], path_to_root[j][2]
if child_nL > child_ns then
-- The old bright gen will now be the dark gen, take equave complement for the new bright gen.
-- new L = old s.
-- The # of new L's in (now dark) generator is # of old L's + # of old s's;
-- the # of new s's in it is the # of old L's.
result = {['L'] = child_nL - (result['L'] + result['s']), ['s'] = child_ns - result['L']}
else -- The old bright gen will stay bright.
-- new s = old s.
-- The # of new L's in the generator is # of old L's;
-- the # of new s's in it is # of old L's + # of new s's.
result = {['L'] = result['L'], ['s'] = result['L'] + result['s']}
end
end
return result
end
return p