pdConstruct {nlme} | R Documentation |

## Construct pdMat Objects

### Description

This function is an alternative constructor for the `pdMat`

class associated with `object`

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.

### Usage

pdConstruct(object, value, form, nam, data, ...)

### Arguments

`object` |
an object inheriting from class `pdMat` , representing
a positive definite matrix. |

`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. |

`...` |
optional arguments for some methods. |

### Value

a `pdMat`

object representing a positive-definite matrix,
inheriting from the same classes as `object`

.

### Author(s)

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

### See Also

`pdCompSymm`

, `pdDiag`

,
`pdIdent`

, `pdNatural`

, `pdSymm`

### Examples

pd1 <- pdSymm()
pdConstruct(pd1, diag(1:4))

[Package

*nlme* version 3.1-57

Index]