coef.pdMat {nlme} | R Documentation

## pdMat Object Coefficients

### Description

This method function extracts the coefficients associated with the positive-definite matrix represented by `object`.

### Usage

    ## S3 method for class 'pdMat':
    coef(object, unconstrained, ...)
    ## S3 method for class 'pdMat':
    coef(object, ...) <- value

### Arguments

`object` | an object inheriting from class `pdMat`, representing a positive-definite matrix.
`unconstrained` | a logical value. If `TRUE` the coefficients are returned in unconstrained form (the same used in the optimization algorithm). If `FALSE` the upper triangular elements of the positive-definite matrix represented by `object` are returned. Defaults to `TRUE`.
`value` | a vector with the replacement values for the coefficients associated with `object`. It must be a vector with the same length of `coef{object}` and must be given in unconstrained form.
`...` | some methods for this generic require additional arguments. None are used in this method.

### Value

a vector with the coefficients corresponding to `object`.

### SIDE EFFECTS

On the left side of an assignment, sets the values of the coefficients of `object` to `value`.

### Author(s)

Jose Pinheiro and Douglas Bates

### References

Pinheiro, J.C. and Bates., D.M. (1996) "Unconstrained Parametrizations for Variance-Covariance Matrices", Statistics and Computing, 6, 289-296.

### See Also

`pdMat`

### Examples

    coef(pdSymm(diag(3)))

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