dsRMatrix-class {Matrix} | R Documentation |

## Symmetric Sparse Compressed Row Matrices

### Description

The `dsRMatrix`

class is a class of symmetric, sparse
matrices in the compressed, row-oriented format. In this
implementation the non-zero elements in the rows are sorted into
increasing column order.

### Objects from the Class

These `"..RMatrix"`

classes are currently still mostly unimplemented!

Objects can be created by calls of the form `new("dsRMatrix", ...)`

.

### Slots

`uplo`

:A character object indicating if the upper
triangle (`"U"`

) or the lower triangle (`"L"`

) is
stored. At present only the lower triangle form is allowed.

`j`

:Object of class `"integer"`

of length
`nnzero`

(number of non-zero elements). These are the row
numbers for each non-zero element in the matrix.

`p`

:Object of class `"integer"`

of pointers, one
for each row, to the initial (zero-based) index of elements in
the row.

`factors`

:Object of class `"list"`

- a list
of factorizations of the matrix.

`x`

:Object of class `"numeric"`

- the non-zero
elements of the matrix.

`Dim`

:Object of class `"integer"`

- the dimensions
of the matrix - must be an integer vector with exactly two
non-negative values.

`Dimnames`

:List of length two, see `Matrix`

.

### Extends

Classes `RsparseMatrix`

, `dsparseMatrix`

and
`symmetricMatrix`

, directly.

Class `"dMatrix"`

, by class `"dsparseMatrix"`

,
class `"sparseMatrix"`

, by class `"dsparseMatrix"`

or
`"RsparseMatrix"`

;
class `"compMatrix"`

by class `"symmetricMatrix"`

and of course,
class `"Matrix"`

.

### Methods

- forceSymmetric
`signature(x = "dsRMatrix", uplo = "missing")`

:
a trivial method just returning `x`

- forceSymmetric
`signature(x = "dsRMatrix", uplo = "character")`

:
if `uplo == x@uplo`

, this trivially returns `x`

;
otherwise `t(x)`

.

- coerce
`signature(from = "dsCMatrix", to = "dsRMatrix")`

### See Also

the classes `dgCMatrix`

,
`dgTMatrix`

, and `dgeMatrix`

.

### Examples

```
(m0 <- new("dsRMatrix"))
m2 <- new("dsRMatrix", Dim = c(2L,2L),
x = c(3,1), j = c(1L,1L), p = 0:2)
m2
stopifnot(colSums(as(m2, "TsparseMatrix")) == 3:4)
str(m2)
(ds2 <- forceSymmetric(diag(2))) # dsy*
dR <- as(ds2, "RsparseMatrix")
dR # dsRMatrix
```

[Package

*Matrix* version 1.5-1

Index]