Matrix (version 1.0-4)

symmpart: 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.

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).

Details

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

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)