pdMat {nlme} | R Documentation |

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`

.

Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu

`pdCompSymm`

, `pdDiag`

,
`pdIdent`

, `pdNatural`

, `pdSymm`

pd1 <- pdMat(diag(1:4), pdClass = "pdDiag") pd1

[Package *nlme* version 3.1-66 Index]