This function gives an alternative way of constructing an object
inheriting from the `pdMat`

class named in `pdClass`

, or
from `data.class(object)`

if `object`

inherits from
`pdMat`

, and is mostly used internally in other functions. See
the documentation on the principal constructor function, generally
with the same name as the `pdMat`

class of object.

`pdMat(value, form, nam, data, pdClass)`

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. Defaults to `numeric(0)`

, corresponding to an
uninitialized object.

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`

.

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`

.

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.

pdClass

an optional character string naming the
`pdMat`

class to be assigned to the returned object. This
argument will only be used when `value`

is not a `pdMat`

object. Defaults to `"pdSymm"`

.

a `pdMat`

object representing a positive-definite matrix,
inheriting from the class named in `pdClass`

, or from
`class(object)`

, if `object`

inherits from `pdMat`

.

Pinheiro, J.C., and Bates, D.M. (2000) "Mixed-Effects Models in S and S-PLUS", Springer.

`pdClasses`

,
`pdCompSymm`

, `pdDiag`

,
`pdIdent`

, `pdNatural`

,
`pdSymm`

,
`reStruct`

,
`solve.pdMat`

,
`summary.pdMat`

```
# NOT RUN {
pd1 <- pdMat(diag(1:4), pdClass = "pdDiag")
pd1
# }
```

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