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

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