Simple, clean easing functions in Lua. Will add more as I need them.

EasingFunctions.lua

-- Input: Time value scaled [0,1]
-- Output: Transformed time value
local function Ease_InOutQuad(t)
	return t<0.5 and 2*t*t or -1-2*(t-2)*t
end
local function Ease_OutQuad(t)
	return -(t-2)*t
end
local function Ease_InBack(t)
	local s = 1.70158
	return t*t*(s*(t-1)+t)
end
local function Ease_OutBack(t)
	local s = 1.70158
	return 1+(t-1)*(t-1)*(-1+t+s*t)
end
local function Ease_InOutBack(t)
	local s = 2.59491
	return t<0.5 and 2*t*t*(-s+2*(1+s)*t) or 1+2*(t-1)*(t-1)*(-2-s+2*(1+s)*t)
end