pdCompSymm {nlme}  R Documentation 
This function is a constructor for the pdCompSymm
class,
representing a positivedefinite matrix with compound symmetry
structure (constant diagonal and constant offdiagonal elements). The
underlying matrix is represented by 2 unrestricted parameters.
When value
is numeric(0)
, an unitialized pdMat
object, a onesided 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 positivedefinite matrix.
pdCompSymm(value, form, nam, data)
value 
an optional initialization value, which can be any of the
following: a 
form 
an optional onesided 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 positivedefinite
matrix and unreplicated elements. This argument is ignored when

data 
an optional data frame in which to evaluate the variables
named in 
a pdCompSymm
object representing a positivedefinite
matrix with compound symmetry structure, also inheriting from class
pdMat
.
JosÃ© Pinheiro and Douglas Bates bates@stat.wisc.edu
Pinheiro, J.C., and Bates, D.M. (2000) "MixedEffects Models in S and SPLUS", Springer, esp. p. 161.
as.matrix.pdMat
,
coef.pdMat
,
matrix<.pdMat
,
pdClasses
pd1 < pdCompSymm(diag(3) + 1, nam = c("A","B","C")) pd1