symmpart: Symmetric Part and Skew(symmetric) Part of a Matrix
In bedatadriven/renjin-matrix: Sparse and Dense Matrix Classes and Methods

Description Usage Arguments Details Value See Also Examples

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.

1 2	symmpart(x) skewpart(x)

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

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

If the row and column names differ, the result will use the column names unless they are (partly) NULL where the row names are non-NULL (see also the examples).

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).

isSymmetric.

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

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

dn <- dimnames(m) <- list(row = c("r1", "r2"), col = c("var.1", "var.2"))
stopifnot(all(m == symmpart(m) + skewpart(m)))
colnames(m) <- NULL
stopifnot(all(m == symmpart(m) + skewpart(m)))
dimnames(m) <- unname(dn)
stopifnot(all(m == symmpart(m) + skewpart(m)))


## investigate the current methods:
showMethods(skewpart, include = TRUE)