Find the trace of a square matrix

Description

Hardly worth coding, if it didn't appear in so many formulae in psychometrics, the trace of a (square) matrix is just the sum of the diagonal elements.

Usage

tr(m)

Arguments

Details

The tr function is used in various matrix operations and is the sum of the diagonal elements of a matrix.

Value

The sum of the diagonal elements of a square matrix.
i.e. tr(m) <- sum(diag(m)).

Examples

 m <- matrix(1:16,ncol=4)
 m
 tr(m)