ddiMatrix-class {Matrix} | R Documentation

## Class "ddiMatrix" of Diagonal Numeric Matrices

### Description

The class `"ddiMatrix"` of numerical diagonal matrices. Note that diagonal matrices now extend `sparseMatrix`, whereas they did extend dense matrices earlier.

### Objects from the Class

Objects can be created by calls of the form `new("ddiMatrix", ...)` but typically rather via `Diagonal`.

### Slots

`x`:
  numeric vector. For an n * n matrix, the `x` slot is of length n or `0`, depending on the `diag` slot:
`diag`:
  `"character"` string, either `"U"` or `"N"` where `"U"` denotes unit-diagonal, i.e., identity matrices.
`Dim`,`Dimnames`:
  matrix dimension and `dimnames`, see the `Matrix` class description.

### Extends

Class `"diagonalMatrix"`, directly. Class `"dMatrix"`, directly. Class `"sparseMatrix"`, indirectly, see `showClass("ddiMatrix")`.

### Methods

%*%
  `signature(x = "ddiMatrix", y = "ddiMatrix")`: ...

### See Also

Class `diagonalMatrix` and function `Diagonal`.

### Examples

    (d2 <- Diagonal(x = c(10,1)))
    str(d2)
    ## slightly larger in internal size:
    str(as(d2, "sparseMatrix"))

    M <- Matrix(cbind(1,2:4))
    M %*% d2 #> `fast' multiplication

    chol(d2) # trivial
    stopifnot(is(cd2 <- chol(d2), "ddiMatrix"),
              all.equal(cd2@x, c(sqrt(10),1)))

[Package Matrix version 0.999375-33 Index]