.\" -*- nroff -*- generated from .Rd format
.BG
.FN pdCompSymm
.TL
Positive-Definite Matrix with Compound Symmetry Structure
.DN
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 unitialized `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.
.CS
pdCompSymm(value, form, nam, data)
.OA
.AG value
an optional initialization value, which can be any of the
following: a `pdMat' object, a positive-definite
matrix, a one-sided linear formula (with variables separated by
`+'), a vector of character strings, or a numeric
vector of length 2. Defaults to `numeric(0)', corresponding to
an uninitialized object.
.AG form
an optional one-sided linear formula specifying the
row/column names for the matrix represented by `object'. Because
factors may be present in `form', the formula needs to be
evaluated on a data.frame to resolve the names it defines. This
argument is ignored when `value' is a one-sided
formula. Defaults to `NULL'.
.AG 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
`value' is a vector of character strings. Defaults to
`NULL'.
.AG data
an optional data frame in which to evaluate the variables named in
`value' and `form'. It is used to obtain the levels for `factors',
which affect the dimensions and the row/column names of the underlying
matrix. If `NULL', no attempt is made to obtain information on
`factors' appearing in the formulas. Defaults to the
parent frame from which the function was called.
.RT
a `pdCompSymm' object representing a positive-definite
matrix with compound symmetry structure, also inheriting from class
`pdMat'.

.SA
`as.matrix.pdMat', `coef.pdMat',
`matrix<-.pdMat'
.EX
pd1 <- pdCompSymm(diag(3) + 1, nam = c("A","B","C"))
pd1
.KW models
.WR
