matrixcalc: is.diagonal.matrix – R documentation

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is.diagonal.matrix

Test for diagonal square matrix

Description

This function returns TRUE if the given matrix argument x is a square numeric matrix and that the off-diagonal elements are close to zero in absolute value to within the given tolerance level. Otherwise, a FALSE value is returned.

Usage

is.diagonal.matrix(x, tol = 1e-08)

Arguments

`x`	a numeric square matrix
`tol`	a numeric tolerance level usually left out

Value

A TRUE or FALSE value.

Author(s)

Frederick Novomestky fnovomes@poly.edu

References

Bellman, R. (1987). Matrix Analysis, Second edition, Classics in Applied Mathematics, Society for Industrial and Applied Mathematics.

Horn, R. A. and C. R. Johnson (1990). Matrix Analysis, Cambridge University Press.

Examples

A <- diag( 1, 3 )
is.diagonal.matrix( A )
B <- matrix( c( 1, 2, 3, 4 ), nrow=2, byrow=TRUE )
is.diagonal.matrix( B )
C <- matrix( c( 1, 0, 0, 0 ), nrow=2, byrow=TRUE )
is.diagonal.matrix( C )

matrixcalc

Collection of functions for matrix calculations

v1.0-3

GPL (>= 2)

Authors

Frederick Novomestky <fnovomes@poly.edu>

Initial release

2012-09-12