dell: Data ellipse in 2D
In p3d: Plot 3d data and fitted surfaces

Description Usage Arguments Value Author(s) See Also Examples

Calculates points on a 2D data ellipse

1	dell(x, y, radius = 1, ...)

`x`	A numeric vector, or a two-column matrix, or a data.frame
`y`	A numeric vector
`radius`	Radius of the ellipse
`...`	Arguments passed to `ell`, including `n`, the number of points on the ellipse.

dell returns an object of class ell consisting of a matrix whose rows are points on the ellipse and, thus, can be plotted with plot or lines.

Georges Monette

ell, cell, ~~~

##---- Should be DIRECTLY executable !! ----
##-- ==>  Define data, use random,
##--	or do  help(data=index)  for the standard data sets.

## The function is currently defined as
function( x, y, radius = 1, ...) {
        if ( (is.matrix(x) && (ncol(x) > 1))|| is.data.frame(x)) mat <- as.matrix(x[,1:2])
        else if (is.list(x)) mat <- cbind(x$x, x$y)
        else mat <- cbind( x,y)
        ell( apply(mat,2,mean), var(mat), radius = radius, ...)
    }