SsdMatrix-class {qpgraph} | R Documentation

## Sum of squares and deviations Matrices

### Description

The `"SsdMatrix"` class is the class of symmetric, dense matrices in packed storage (just as a `dspMatrix-class`, i.e., only the upper triangle is stored) defined within the `qpgraph` package to store corrected, or uncorrected, matrices of the sum of squares and deviations (SSD) of pairs of random variables. A corrected SSD matrix corresponds to a sample covariance matrix.

### Objects from the Class

Objects can be created by calls of the form `new("SsdMatrix", ...)` or by using `qpCov()` which estimates a sample covariance matrix from data returning an object of this class.

### Slots

`ssd`:

  Object of class `dspMatrix-class` storing the SSD matrix.

`n`:

  Object of class `"numeric"` storing the sample size employed to estimate the SSD matrix stored in the slot `ssd`. This is specially relevant when the SSD matrix was estimated from data with missing values by using complete observations only, which is the default mode of operation of `qpCov()`.

### Extends

`"SsdMatrix"` extends class `"dspMatrix"`, directly.

### Methods

dim

  `signature(x = "SsdMatrix")`

dimnames

  `signature(x = "SsdMatrix")`

show

  `signature(object = "SsdMatrix")`

det

  `signature(object = "SsdMatrix")`

determinant

  `signature(object = "SsdMatrix", logarithm = "missing")`

determinant

  `signature(object = "SsdMatrix", logarithm = "logical")`

[Package qpgraph version 2.16.0 Index]