Functions for Drawing Ellipses and Ellipse-Like Confidence
Regions
Duncan Murdoch and E. D. Chow (porting to R by Jesus M. Frias Celayeta)
Contains various routines for drawing
    ellipses and ellipse-like confidence regions, implementing the plots
    described in Murdoch and Chow (1996, <doi:10.2307/2684435>). There are
    also routines implementing the profile plots described in Bates and
    Watts (1988, <doi:10.1002/9780470316757>).