From 7961ba4565d6e7ee501f0b940089cc9c57dd1c61 Mon Sep 17 00:00:00 2001
From: Dennis Schridde <dschridde@welfenlab.de>
Date: Wed, 27 Nov 2013 01:36:07 +0100
Subject: [PATCH] Extension for large (>3D) vectors and segment and x/y/z/w
 convenience

Support for:
 local m = matrix{1,2,3,4,5,6,...}
 m:segment(3)[2] -->> matrix{2,3,4}
 m:y() -->> 2
---
 lua/matrix.lua | 43 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/lua/matrix.lua b/lua/matrix.lua
index 83f7d57..e81951d 100644
--- a/lua/matrix.lua
+++ b/lua/matrix.lua
@@ -134,7 +134,11 @@ function matrix:new( rows, columns, value )
 	if type( rows ) == "table" then
 		-- check for vector
 		if type(rows[1]) ~= "table" then -- expect a vector
-			return setmetatable( {{rows[1]},{rows[2]},{rows[3]}},matrix_meta )
+			local o = {}
+			for i,v in ipairs(rows) do
+				o[i] = {v}
+			end
+			return setmetatable( o,matrix_meta )
 		end
 		return setmetatable( rows,matrix_meta )
 	end
@@ -189,6 +193,43 @@ setmetatable( matrix, { __call = function( ... ) return matrix.new( ... ) end }
 --		but one should avoid using symbolic matrices with complex ones
 --		since it is not clear which metatable then is used
 
+
+local segment = {}
+
+function segment:__index(base_row)
+	local o = matrix(self.size,1)
+	for i=1,self.size do
+		o[i][1] = self.matrix[base_row+i-1][1]
+	end
+	return o
+end
+
+function segment:__newindex(base_row, o)
+	assert(self.size == #o)
+	for i=1,self.size do
+		self.matrix[base_row+i-1] = o[i]
+	end
+end
+
+function matrix:segment(size)
+	local o = {matrix=self, size=size}
+	return setmetatable(o, segment)
+end
+
+function matrix:x()
+	return self[1][1]
+end
+function matrix:y()
+	return self[2][1]
+end
+function matrix:z()
+	return self[3][1]
+end
+function matrix:w()
+	return self[4][1]
+end
+
+
 --// matrix.add ( m1, m2 )
 -- Add two matrices; m2 may be of bigger size than m1
 function matrix.add( m1, m2 )