Module:Temperament data

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This module should not be invoked directly; use its corresponding template instead: Template:Temperament data.

Module:Temperament data is a draft module. It is incomplete and may not be in active development. If possible, editors are encouraged to help with its development. In the meantime, editors should avoid using this module across the Xenharmonic Wiki, except for testing.

Introspection summary for Module:Temperament data
Functions provided (1) Line Function Params 110 get_te_generator (subgroup, mapping, gens)	Lua modules required (1) Variable Module Functions used rat Module:Rational dependency not used

No function descriptions were provided. The Lua code may have further information.

---

local rat = require('Module:Rational')
local p = {}
-- Utility / matrix functions
local function gcd(a,b)
  if type(a) == "number" and type(b) == "number" and 
        a == math.floor(a) and b == math.floor(b) then
    if b == 0 then
      return a
    else
      return gcd(b, a % b) -- tail recursion
    end
  else
    error("Invalid argument to gcd (" .. tostring(a) .. "," .. 
          tostring(b) .. ")", 2)
  end
end


local function matadd(a, b)
	local result = {}
	for i = 1, #a  do
		result[i] = {}
		for j = 1, #(b[1]) do
			result[i][j] = a[i][j] + b[i][j]
		end
	end
	return result
end

local function matsub(a, b)
	local result = {}
	for i = 1, #a  do
		result[i] = {}
		for j = 1, #(b[1]) do
			result[i][j] = a[i][j] - b[i][j]
		end
	end
	return result
end

local function matmul(a, b)
	local result = {}
	for i = 1, #a  do
		result[i] = {}
		for j = 1, #(b[1]) do
			result[i][j] = 0
			for k = 1, #(a[1]) do
				result[i][j] = result[i][j] + (a[i][k] * b[k][j])
			end
		end
	end
	return result
end


local function scalarmatmul(a, b)
	local result = {}
	for i = 1, #a  do
		result[i] = {}
		for j = 1, #(a[1]) do
			result[i][j] = a[i][j] * b
		end
	end
	return result
end

local function matinv(a)
	dbl_identity = {}
	for i = 1, #a do
		dbl_identity[i] = {}
		for j = 1, #a do
			if i == j then
				dbl_identity[i][j] = 2
			else
				dbl_identity[i][j] = 0
			end
		end
	end

	xn = scalarmatmul(a, 0.000001)
	
	for i = 1, 30 do
		xn = matmul(xn, matsub(dbl_identity, matmul(a, xn)))
	end
	return xn
end

local function transpose(a)
	local result = {}
	for i = 1, #a[1] do
		result[i] = {}
		for j = 1, #a do
			result[i][j] = a[j][i]
		end
	end
	return result
end

local function pseudoinv(a)
	return matmul(transpose(a), matinv(matmul(a, transpose(a))))
end


-- Actual temperament-related functions start here
-- Generator list (e.g. 2/1, 3/2 for meantone) is needed so you can input irregular mappings like {{5,8,12},{7,11,16}} for meantone
-- and still have the outputted generators be ~2/1 and ~3/2
-- (this will be important later so people using the template can just input an ET list instead of having to figure out the mapping)
-- Generators are passed as monzos in the specified subgroup here

function p.get_te_generator(subgroup, mapping, gens)
	local w = {}
	for i = 1, #subgroup do
		w[i] = {}
		for j = 1, #subgroup do
			if i == j then
				w[i][j] = math.log(2)/math.log(subgroup[i])
			else
				w[i][j] = 0
			end
		end
	end
	
	local jw = {{}}
	for i = 1, #subgroup do
		jw[1][i] = 1
	end
	local vw = matmul(mapping, w)
	local g = matmul(jw, pseudoinv(vw))
	
	local mapping_cols = #mapping[1]
	local tempered_subgroup = {}
	
	for i = 1, #subgroup do
		tempered_subgroup[i] = 0
		for j = 1, #mapping do
			tempered_subgroup[i] = tempered_subgroup[i] + g[1][j] * mapping[j][i]
		end
	end
	
	return tempered_subgroup
end





return p