"The Reverse EMA Indicator" author John Ehlers presents a causal forward and backward EMA indicator that can be used in real trading. It has double smoothing at the high end of the spectrum to reduce aliased components and is able to mitigate the impact of spectral dilation at the low end. The author describes the indicator as having unique flexibility in that it can display trend or cycle information by varying the alpha parameter and do this with very low lag.