| pdCompSymm {nlme} | R Documentation |
Positive-Definite Matrix with Compound Symmetry Structure
Description
This function is a constructor for the pdCompSymm class,
representing a positive-definite matrix with compound symmetry
structure (constant diagonal and constant off-diagonal elements). The
underlying matrix is represented by 2 unrestricted parameters.
When value is numeric(0), an uninitialized pdMat
object, a one-sided formula, or a vector of character strings,
object is returned as an uninitialized pdCompSymm
object (with just some of its attributes and its class defined) and
needs to have its coefficients assigned later, generally using the
coef or matrix replacement functions. If value is
an initialized
pdMat object, object will be constructed from
as.matrix(value). Finally, if value is a numeric vector
of length 2, it is assumed to represent the unrestricted coefficients
of the underlying positive-definite matrix.
Usage
pdCompSymm(value, form, nam, data)
Arguments
value |
an optional initialization value, which can be any of the
following: a |
form |
an optional one-sided linear formula specifying the
row/column names for the matrix represented by |
nam |
an optional vector of character strings specifying the
row/column names for the matrix represented by object. It must have
length equal to the dimension of the underlying positive-definite
matrix and unreplicated elements. This argument is ignored when
|
data |
an optional data frame in which to evaluate the variables
named in |
Value
a pdCompSymm object representing a positive-definite
matrix with compound symmetry structure, also inheriting from class
pdMat.
Author(s)
José Pinheiro and Douglas Bates bates@stat.wisc.edu
References
Pinheiro, J.C., and Bates, D.M. (2000) "Mixed-Effects Models in S and S-PLUS", Springer, esp. p. 161.
See Also
as.matrix.pdMat,
coef.pdMat,
matrix<-.pdMat,
pdClasses
Examples
pd1 <- pdCompSymm(diag(3) + 1, nam = c("A","B","C"))
pd1