15.66.2  Algorithm 

The  data is smoothed by repeatedly transforming the points and residuals,
using  running  means,  quadratic  interpolation,  and  hanning.   Similar
algorithms  are  described in Exploratory Data Analysis by John W Tukey at
SLAC.  This has been modified slightly by  J.   Clement  to  treat  sparse
statistical  data  correctly.   The  original  alogorithm would throw away
isolated data points which were larger than the surrounding data.