[R] calculating/plotting error ellipses

[Jan M. Wiener]

hello,
sorry for posting what may be a simple question:
i do have a matrix of coordinates (positional judgments, see below) and
now want to calculate and plot the corresponding error ellipse.
can anyone help me with the exact steps/syntax?

 > xyDat
            X         Y
1    -0.49    -2.13
2     0.91     0.48
3     0.20    -2.80
4    -0.76    -3.23
5    -0.36     2.50
6     1.38     1.24
7    -1.73    -2.14
8    -0.28    -1.97
9    -2.65     0.91
10    -2.03     0.92
11     0.40    -1.54
12    -1.40     2.39

thank you very much in advance.
best jan