symmpart {Matrix}R Documentation

Symmetric Part and Skew(symmetric) Part of a Matrix

Description

symmpart(x) computes the symmetric part (x + t(x))/2 and skewpart(x) the skew symmetric part (x - t(x))/2 of a square matrix x, more efficiently for specific Matrix classes.

Note that x == symmpart(x) + skewpart(x) for all square matrices – apart from extraneous NA values in the RHS.

Usage

symmpart(x)
skewpart(x)

Arguments

x

a square matrix; either “traditional” of class "matrix", or typically, inheriting from the Matrix class.

Details

These are generic functions with several methods for different matrix classes, use e.g., showMethods(symmpart) to see them.

Value

symmpart() returns a symmetric matrix, inheriting from symmetricMatrix iff x inherited from Matrix.

skewpart() returns a skew-symmetric matrix, typically of the same class as x (or the closest “general” one, see generalMatrix).

Examples

m <- Matrix(1:4, 2,2)
symmpart(m)
skewpart(m)

stopifnot(all(m == symmpart(m) + skewpart(m)))

## investigate the current methods:
showMethods(skewpart, include = TRUE)
[Package Matrix version 1.0-6 Index]