function math.sign(x)
	if x<0 then
		return -1
	elseif x>0 then
		return 1
	else
		return 0
	end
end

function vector(init_x, init_y, final_x, final_y)
	local distance_x = final_x - init_x
	local distance_y = final_y - init_y
	return {distance_x, distance_y}
end

function getVectorValue(vector)
	return math.sqrt(vector[1] ^ 2 + vector[2] ^ 2)
end

function getAngleFromVector(x,y)
	local reduce = 0
	if x < 0 then
		reduce = math.rad(180)
	end
	return math.atan(y/x) - reduce
end