corMatrix.corStruct {nlme} | R Documentation |

## Matrix of a corStruct Object

### Description

This method function extracts the correlation matrix (or its transpose
inverse square-root factor), or list of correlation matrices (or their
transpose inverse square-root factors) corresponding to
`covariate`

and `object`

. Letting *S* denote
a correlation matrix, a square-root factor of *S* is
any square matrix *L* such that *S=L'L*. When
`corr = FALSE`

, this method extracts *L^(-t)*.

### Usage

## S3 method for class 'corStruct':
corMatrix(object, covariate, corr, ...)

### Arguments

`object` |
an object inheriting from class `corStruct`
representing a correlation structure. |

`covariate` |
an optional covariate vector (matrix), or list of
covariate vectors (matrices), at which values the correlation matrix,
or list of correlation matrices, are to be evaluated. Defaults to
`getCovariate(object)` . |

`corr` |
a logical value. If `TRUE` the function returns the
correlation matrix, or list of correlation matrices, represented by
`object` . If `FALSE` the function returns a transpose
inverse square-root of the correlation matrix, or a list of transpose
inverse square-root factors of the correlation matrices. |

`...` |
some methods for this generic require additional
arguments. None are used in this method. |

### Value

If `covariate`

is a vector (matrix), the returned value will be
an array with the corresponding correlation matrix (or its transpose
inverse square-root factor). If the `covariate`

is a list of
vectors (matrices), the returned value will be a list with the
correlation matrices (or their transpose inverse square-root factors)
corresponding to each component of `covariate`

.

### Author(s)

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

### See Also

`corFactor.corStruct`

, `Initialize.corStruct`

### Examples

cs1 <- corAR1(0.3)
corMatrix(cs1, covariate = 1:4)
corMatrix(cs1, covariate = 1:4, corr = FALSE)

[Package

*nlme* version 3.1-66

Index]