.\" -*- nroff -*- generated from .Rd format
.BG
.FN corBand
.TL
Banded Correlation Structure
.DN
This function is a constructor for the `corBand' class,
representing a banded correlation structure. The internal
representation of this structure, in terms of unconstrained
parameters, uses the spherical parameterization defined in Pinheiro and
Bates (1996).  Objects created using this constructor must later be
initialized using the  appropriate `initialize' method.
.CS
corBand(value, form, fixed, ord)
.OA
.AG value
an optional vector with the parameter values. Default is
`numeric(0)', which results in a vector of zeros of appropriate
dimension being assigned to the parameters when `object' is
initialized (corresponding to an identity correlation structure).
.AG form
a one sided formula of the form `~ t', or `~ t |
     g', specifying a time covariate `t' and,  optionally, a
grouping factor `g'.  A covariate for this correlation structure
must such that its unique values form a sequence of consecutive
integers.  When a grouping factor is present in
`form', the correlation structure is assumed to apply only
to observations within the same grouping level; observations with
different grouping levels are assumed to be uncorrelated. Defaults to
`~ 1', which corresponds to using the order of the observations
in the data as a covariate, and no groups.
.AG fixed
an optional logical value indicating whether the
coefficients should be allowed to vary in the optimization, or kept
fixed at their initial value. Defaults to `FALSE', in which case
the coefficients are allowed to vary.
.AG ord
an optional integer specifying the order of the banded
matrix represented by the returned `corBand' object, defined as
the number of nonzero diagonals in the upper-triangular part of the
matrix. Defaults to 2.
.RT
an object of class `corBand' representing a banded correlation
structure.
.SH REFERENCES
Pinheiro, J.C. and Bates., D.M.  (1996) "Unconstrained
Parametrizations for Variance-Covariance Matrices", Statistics and
Computing, 6, 289-296.
.SA
`initialize.corStruct'
.EX
## covariate is observation order and grouping factor is Subject
cs1 <- corBand(form = ~ 1 | Subject)
.KW models
.WR
