         {
             return 0.5 * position * position
         }
-        return -0.5 * ((--position) * (position - 2.0) - 1.0)
+        
+        return -0.5 * ((position - 1.0) * (position - 3.0) - 1.0)
     }
     
     internal static let EaseInCubic = { (elapsed: NSTimeInterval, duration: NSTimeInterval) -> Double in

    
    internal static let EaseOutCirc = { (elapsed: NSTimeInterval, duration: NSTimeInterval) -> Double in
        var position = Double(elapsed / duration)
        position--
        return Double( sqrt(1 - position * position) )
    }
    

    
    internal static let EaseOutCubic = { (elapsed: NSTimeInterval, duration: NSTimeInterval) -> Double in
        var position = Double(elapsed / duration)
        position -= 1.0
        return (position * position * position + 1.0)
    }
    
