plotSigmaEllipse: Plot an ellipse based on a correlation matrix
In siar: Stable Isotope Analysis in R

A utility function for quickly adding an ellipse to an existing graph based on a correlation matrix defining the ellipse's parameters.

1	plotSigmaEllipse(m,sigma,steps=5,col="black",lwd=1,lty=2)

`m`	A vector of length 2 containing the centres of the ellipse (i.e. the means of the ellipse).
`sigma`	A 2x2 matrix representing the correlation matrix that defines the ellipse.
`steps`	A visual rendering option that sets the number of step-size and hence resolution of the points used to draw the lines defining the ellipses. The larger the value, the more angular the ellipses will appear.
`col`	The colour to use in the plot see `par`.
`lty`	The line type to use in the plot see `par`.
`lwd`	The line width to use in the plot see `par`.