projector-class {dae} | R Documentation |

## Class projector

### Description

The class "`projector`

" is the
subclass of matrices that are square, symmetric and idempotent.

`is.projector`

is the membership function for this class.

`degfree`

is the extractor function for the degrees of freedom and
`degfree<-`

is the replacement function.

`correct.degfree`

checks whether the stored degrees of freedom are correct.

### Objects from the Class

An object of class "`projector`

" consists of a
square, symmetric, idempotent matrix along with its degrees of freedom (rank).

Objects can be created by calls of the form `new("projector", data, nrow, ncol, byrow, dimnames, ...)`

.
However, this does not add the degrees of freedom to the object. These can be
added using the replacement function `degfree<-`

.
Alternatively, the function `projector`

creates the new object
from a `matrix`

, adding its degrees of freedom at the same time.

### Slots

`.Data`

:Object of class

`"matrix"`

`degfree`

:Object of class

`"integer"`

### Extends

Class "`matrix`

", from data part.
Class "`array`

", by class "matrix", distance 2.
Class "`structure`

", by class "matrix", distance 3.
Class "`vector`

", by class "matrix", distance 4, with explicit coerce.

### Methods

- coerce
`signature(from = "projector", to = "matrix")`

`signature(x = "projector")`

- show
`signature(object = "projector")`

### Author(s)

Chris Brien

### See Also

`projector`

, `degfree`

, `correct.degfree`

in package dae.

### Examples

```
showClass("projector")
## set up a 2 x 2 mean operator that takes the mean of a vector of 2 values
m <- matrix(rep(0.5,4), nrow=2)
## create an object of class projector
proj.m <- projector(m)
## check that it is a valid projector
is.projector(proj.m)
## create a projector based on the matrix m
proj.m <- new("projector", data=m)
## add its degrees of freedom and print the projector
degfree(proj.m) <- proj.m
```

*dae*version 3.2.28 Index]