The Inverse Fisher Transform is used in the Elegant Oscillator to convert a normalized derivative of a price series to the +/-1 range. The normalization is done by dividing by the square root of the sum of squares, a sort of N-dimensional distance. Using the Inverse Fisher Transform is supposedly a better method than simply clipping the data. The result is smoothed by Ehlers’ ‘SuperSmoother’, a low-lag lowpass filter.According to Ehlers, its peaks and valleys that exceed a threshold can be used for mean reversion trading.