| symmpart-methods {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
|
Details
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).
Value
symmpart(x) returns a symmetric matrix,
inheriting from symmetricMatrix
or diagonalMatrix if x
inherits from Matrix.
skewpart(x) returns a skew-symmetric matrix,
inheriting from generalMatrix,
symmetricMatrix or
diagonalMatrix if x
inherits from Matrix.
See Also
Examples
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)