(1) The ellipse package, according to its DESCRIPTION file, is a package of
``Functions for drawing ellipses and ellipse-like confidence regions''.
nothing to do with *fitting* ellipses.
(2) What on earth do you mean by ``fit an elipse (sic) to two lines of
(3) There are (infinitely) many ellipses that could be associated with a
plot such as that displayed in the figure you refer. (E.g. confidence
predication ellipses, one of each for each level of confidence.) You
will have to
be much clearer and much more precise about what you wish to accomplish
in order to get any help.