There are three groups of routines in the ellipse package.  The first
consists of those involved with plotcorr, which implements the plots
described in Murdoch, D.J. and Chow, E.D. (1996).  A graphical display of
large correlation matrices. {\em The American Statistician} {\bf
50},178-180. These display correlations using ellipses, whose shape is that
of the contours of a bivariate normal distribution with matching
correlation.
    
The second group implements a version of the profile plots described in
Bates and Watts (1988), Nonlinear Regression Analysis and its
Applications.

The last group provide the basis for the others, drawing ellipses based on
various S objects, including scalar correlations, covariance matrices,
arima, lm, and nls fits.

ellipse                  Generic function to make an ellipse
ellipse.default          Produces an ellipse from a covariance matrix or
                         a correlation
ellipse.arima0           Outline approximate pairwise confidence region
                         for arima0 object
ellipse.glm              Outline an approximate pairwise confidence
                         region for a glm object          
ellipse.lm               Outline a pairwise confidence region for a
                         linear model fit object
ellipse.nls              Outline an approximate pairwise confidence
                         region for an nls object
ellipse.profile          Profile sketch
ellipse.profile.nls      Profile sketch
pairs.profile            Profile pairs
pairs.profile.nls        Profile pairs
plotcorr                 Plot correlation matrix ellipses
