SIBER (version 2.1.9)

sigmaSEA: Calculate metrics corresponding to the Standard Ellipse based on a covariance matrix

Description

This function takes a covariance 2x2 matrix Sigma and returns various metrics relating to the corresponding Standard Ellipse. The function is limited to the 2-dimensional case, as many of the ancillary summary statistics are not defined for higher dimensions (e.g. eccentricity).

Usage

sigmaSEA(sigma)

Value

A list comprising the following metrics for summarising the Standard Ellipse

• SEA the Standard Ellipse Area (not sample size corrected).

• eccentricity a measure of the elongation of the ellipse.

• a the length of the semi-major axis.

• b the length of the semi-minor axis.

Arguments

sigma

a 2x2 covariance ellipse.

Examples

# A perfect circle
sigma <- matrix( c(1, 0, 0, 1), 2, 2)
sigmaSEA(sigma)