Module:JI ratio finder: Difference between revisions

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@@ Line 22: / Line 22: @@
 	local equave = equave or rat.new(2)
 	return rat.mul(rat.inv(ratio), equave)
+end
+-- Determines whether a ratios is within a subgroup; for a subgroup p1.p2..pn,
+-- a ratio p/q is in that subgroup if its prime factorization contains any prime
+-- factors p1, p2, .. pn.
+function p.within_subgroup(ratio, subgroup)
+	local ratio = ratio or rat.new(5, 2)
+	local subgroup = subgroup or { 2, 3, 5 }
+	local within_subgroup = ""
+	for key, value in pairs(ratio) do
+		if key ~= "sign" then
+			within_subgroup = within_subgroup and utils.table_contains(subgroup, key)
+		end
+	end
+	return within_subgroup
 end
@@ Line 47: / Line 64: @@
 			if is_simplified and is_within_cents and is_within_prime_limit then
+				table.insert(candidate_ratios, current_ratio)
+			end
+			numerator = numerator + 1
+		until not is_within_cents
+	end
+	return candidate_ratios
+end
+-- Finds candidate ratios up to a cent value, up to a denominator limit, and
+-- within a prime subgroup.
+-- These ratios should be filtered as needed.
+function p.find_candidate_ratios_within_subgroup(cents, denominator_limit, subgroup)
+	local cents = cents or 1200
+	local denominator_limit = denominator_limit or 99
+	local subgroup = subgroup or { 2, 3, 7, 11 }
+	local candidate_ratios = {}
+	for i = 1, denominator_limit do
+		local denominator = i
+		local numerator = i
+		local is_within_cents = true
+		repeat
+			local current_ratio = rat.new(numerator, denominator)
+			local is_simplified = utils._gcd(numerator, denominator) == 1
+			local is_within_subgroup = p.within_subgroup(current_ratio, subgroup)
+			is_within_cents = rat.cents(current_ratio) <= cents
+			if is_simplified and is_within_cents and is_within_subgroup then
 				table.insert(candidate_ratios, current_ratio)
 			end
@@ Line 120: / Line 170: @@
 		if rat.max_prime(ratios[i]) == harmonic_class then
 			table.insert(filtered_ratios, ratios[i])
+		end
+	end
+	return filtered_ratios
+end
+-- Filters ratios by prime subgroup (such as 2.3.5)
+-- Filters out ratios whose factors are not in the given subgroup; this requires
+-- filtering by each prime as a harmonic class
+function p.filter_ratios_by_subgroup(ratios, subgroup)
+	local ratios = ratios or { rat.new(1), rat.new(5, 4), rat.new(81, 64), rat.new(9, 7) }
+	local subgroup = subgroup or { 2, 3, 5 }
+	local candidate_ratios = p.filter_ratios_by_prime_limit(ratios, subgroup[#subgroup])
+	local filtered_ratios = {}
+	for i = 1, #subgroup do
+		local prime_filtered_ratios = p.filter_ratios_by_harmonic_class(candidate_ratios, subgroup[i])
+		for j = 1, #prime_filtered_ratios do
+			table.insert(filtered_ratios, prime_filtered_ratios[j])
 		end
 	end