pdMat-class {lme4} | R Documentation

## Class pdMat, positive-definite matrices

### Description

A virtual class of parameterized positive-definite symmetric matrices. This class describes the slots and methods that actual classes of positive-definite matrices are expected to incorporate. Some classes that inherit from `pdMat` have additional slots and methods.

### Objects from the Class

Objects of class `pdMat` are not constructed directly; only objects from classes that inherit from `pdMat` are constructed.

### Slots

`form`:
  Object of class `"formula"`, holds the formula for the object
`Names`:
  Object of class `"character"` holding the names of the rows (and columns) of the positive-definite symmetric matrix represented by the object.
`param`:
  `"numeric"` - the parameter vector.
`Ncol`:
  `"integer"` - the number of columns (and rows) in the matrix.
`factor`:
  `"matrix"` - a square-root factor of the matrix.
`logDet`:
  `"numeric"` - the logarithm of the determinant of the factor.

### Methods

coerce
  `signature(from = "pdMat", to = "pdfactor")`: extract a square-root factor of the matrix represented by the object. This factor has a `logDet` slot giving the logarithm of its determinant. In the case of `pdLogChol` these are both scalars and the `logDet` attribute is the logarithm of the absolute value of the factor.
corMatrix
  `signature(object = "pdMat")`: Extract the correlation matrix corresponding to the positive-definite matrix represented by the object. This method is present for back compatibility only. The preferred way of extracting the correlation matrix is to coerce the object to the `"corrmatrix"` class.
dim
  `signature(x = "pdMat")`: the dimensions of the positive-definite matrix represented by the object.
formula
  `signature(x = "pdMat")`: extract the formula
isInitialized
  `signature(object = "pdMat")`: `TRUE` if the object has been initialized, otherwise `FALSE`.
logDet
  `signature(object = "pdMat", covariate = "missing")`: the logarithm of the determinant of the factor of the positive-definite matrix represented by the object.
names
  `signature(x = "pdMat")`: extract a vector of names, which are both the column names and the row names of the positive-definite matrix represented by the object.
names<-
  `signature(x = "pdMat")`: assign the names,
pdFactor
  `signature(object = "pdMat")`: Extract the square root factor of positive-definite symmetric matrix represented by the object. This method is present for back compatibility only. The preferred way of extracting the factor is to coerce the object to the `"pdfactor"` class.
pdMatrix
  `signature(object = "pdMat")`: Extract the positive-definite symmetric matrix represented by the object. This method is present for back compatibility only. The preferred way of extracting the positive-definite symmetric matrix is to coerce the object to the `"pdmatrix"` class.
show
  `signature(x = "pdMat")`: show the object.
solve
  `signature(a = "pdMat", b = "missing")`: Create an object of the same class representing the inverse of the positive-definite matrix.
summary
  `signature(object = "pdMat")`:

### Note

`pdMat` objects are primarily used to represent the variance-covariance matrix or the precision matrix of random-effects terms in mixed-effects models. Frequently they are constructed from a formula only in the call to the mixed-effects modelling function then assigned a value as part of the initialization of the model.

### References

### See Also

`pdCompSymm-class`, `pdDiag-class`, `pdLogChol-class`, `pdIdent-class`

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