\chapter{Non-stationary regularization}
\label{chap:nonstat}

%% Started 03/01/98
%%\def\figdir{./../bob2/Figs}
%\lefthead{Clapp}
%\righthead{Regularizing with non-stationary PEFs}
%\footer{SEP--103}
%\sepinput{macros}
%\email{bob@sep.stanford.edu}
%
%\title{Regularizing tomography with non-stationary filters}
%\author{Robert G. Clapp}
%
%\sepinput{abs}

\section{Introduction}
\sepinput{intro}

%\section{Background}
%\sepinput{regbasic}
%\sepinput{covar}
%\subsection{Steering filters}
%\sepinput{steer}
%\sepinput{build}

\section{Discontinuities and steering filters}
\sepinput{dis}

\section{Estimating a non-stationary filter}
\sepinput{est}

\section{Missing data}
\sepinput{mis}

\section{Tomography}
\sepinput{tomo}

%\section{Conclusions}
%Non-stationary PEFs are an effective interpolator,
%especially when the model has discontinuities, for missing data problems
%and an effective regularizer for tomography problems.
%The weakness of the approach, the requirement that we have field
%to estimate the PEF from, can be turned into a strength by allowing
%a geologist's conception of the velocity to be directly encoded into the
%regularization.
%A more illuminating 
%test of the non-stationary regularization of
%tomography would be on a model with sharp, rather
%%than smooth, boundaries.  
