Uradamus

function shuffle(tbl)
  for i = #tbl, 2, -1 do
    local j = math.random(i)
    tbl[i], tbl[j] = tbl[j], tbl[i]
  end
  return tbl
end

Uradamus

function Class (arg1, arg2, arg3)
    local obj = {}
        obj.var1 = arg1
        obj.var2 = arg2
        obj.var3 = arg3
        
        function obj:out (arg)
            print(self[arg])
        end
    

Uradamus

For a short intro on vectors you can check out a set of 5 tutorials from Rodrigo Monteiro's blog, Higher-Order Fun:
http://higherorderfun.com/blog/2009/06/07/math-for-game-programmers-01-introduction
http://higherorderfun.com/blog/2009/06/07/math-for-game-programmers-02-vectors-101
http://higherorderfun.com/blog/2009/06/13/math-for-game-programmers-03-geometrical-representation-of-vectors
http://higherorderfun.com/blog/2010/02/23/math-for-game-programmers-04-operations-on-vectors
http://higherorderfun.com/blog/2012/06/03/math-for-game-programmers-05-vector-cheat-sheet

After that the blog for Wolfire Games has a set of 4 tutorials going a bit further with vectors and getting into some linear algebra basics:
http://blog.wolfire.com/2009/07/linear-algebra-for-game-developers-part-1
http://blog.wolfire.com/2009/07/linear-algebra-for-game-developers-part-2

Uradamus

function love.load()
    local start_x = 0
    local start_y = 0
    local end_x = 10
    local end_y = 5

    dx = (end_x - start_x)
    dy = (end_y - start_y)

    local distance = math.sqrt(dx^2 + dy^2)