Module:Mediants: Difference between revisions

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@@ Line 9: / Line 9: @@
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--- Filter functions determine whether a mediant meets a specific criteria (eg,
+-- Filter functions determine whether a mediant meets a specific criteria for
--- int limit), based on either the mediant itself, its search depth, or both.
+-- being added to a set of mediants, be it based on something about the mediant,
--- This filter adds (or excludes) mediants based on int limit, and does nothing
+-- its search depth, or both.
--- with the depth param.
+-- A filter function has three params: mediant, depth, and a set of args, which
+-- can be a single value or a table of values.
+-- Int limit filter determines whether a ratio is within an int limit. Does not
+-- use depth.
 function p.int_limit_filter(mediant, depth, int_limit)
-	local int_max = math.max(mediant[1], mediant[2])
+	return math.max(mediant[1], mediant[2]) <= int_limit
-	return int_max <= int_limit
 end
--- This filter adds (or excludes) mediants based on search depth, and does
+-- Depth filter determines whether a ratio is within a target depth. Does not
--- nothing with the mediant itself.
+-- use the mediant itself.
 function p.search_depth_filter(mediant, depth, search_depth)
 	return depth <= search_depth
+end
+-- Tenney height filter determines whether a ratio is within a target Tenney
+-- height. Does not use depth.
+function p.tenney_height_filter(mediant, depth, tenney_height)
+	return math.log(mediant[1] * mediant[2]) / math.log(2) <= tenney_height
 end
 --------------------------------------------------------------------------------
-------------------------------- SEARCH FUNCTIONS -------------------------------
+---------------------------- GENERAL SEARCH FUNCTION ---------------------------
 --------------------------------------------------------------------------------
--- Find mediants by depth, how many times mediants are found in a set of ratios.
+-- General search function searches for mediants using a filter function. A
-function p.find_mediants_by_depth(init_ratios, depth)
+-- custom filter function can be passed in to "filter" out mediants. Ratios
-	local init_ratios = init_ratios or {{1,1}, {1,0}}
+-- are added using a while loop, which exits if a loop iteration adds no new
-	local depth = depth or 5
+-- ratios.
-	local ratios = {}
-	local depths = {}
-	local filter_args = depth
-	local filter_func = p.search_depth_filter
-	ratios, depths = p.find_mediants_by_filter(init_ratios, filter_func, filter_args)
-	return ratios, depths
-end
 -- Find mediants by filter, where the filter function and its args are passed in
@@ Line 85: / Line 85: @@
 	end
 	return ratios, depths
+end
+-- Find mediants by filter, where the filter function and its args are passed in
+-- as part of the function call. Only returns mediants, not depths.
+function p.find_only_mediants_by_filter(init_ratios, filter_func, filter_args)
+	local init_ratios = init_ratios or {{1,1}, {1,0}}
+	local ratios, depths
+	ratios, depths = p.find_mediants_by_filter(init_ratios, filter_func, filter_args)
+	return ratios
+end
+--------------------------------------------------------------------------------
+------------------------- DEPTH-BASED SEARCH FUNCTION --------------------------
+--------------------------------------------------------------------------------
+-- Depth-based search finds mediants by building a tree of mediants up to a
+-- specified depth. This is made a standalone function under the reasoning that
+-- depth-based search is a common enough operation (EG, JI ratio search, tuning
+-- spectrum step ratio search).
+-- Find mediants by depth, how many times mediants are found in a set of ratios.
+function p.find_mediants(init_ratios, depth)
+	local init_ratios = init_ratios or {{1,1}, {1,0}}
+	local depth = depth or 5
+	local ratios, depths
+	ratios, depths = p.find_mediants_by_filter(init_ratios, p.search_depth_filter, depth)
+	return ratios, depths
+end
+-- Find mediants by depth, how many times mediants are found in a set of ratios.
+-- Does not return depths.
+function p.find_only_mediants(init_ratios, depth)
+	local init_ratios = init_ratios or {{1,1}, {1,0}}
+	local depth = depth or 5
+	local ratios, depths
+	ratios, depths = p.find_mediants_by_filter(init_ratios, p.search_depth_filter, depth)
+	return ratios
 end
@@ Line 95: / Line 137: @@
 	local ratios, depths = p.find_mediants_by_filter({{1,1}, {1,0}}, func, 12)
-	ratios = p.find_mediants_by_depth({{1,1}, {1,0}}, 6)
+	ratios = p.find_mediants({{1,1}, {1,0}}, 6)
 	local generators = {}
 	for i = 1, #ratios do