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

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