is.projector {dae} | R Documentation |

## Tests whether an object is a valid object of class projector

### Description

Tests whether an `object`

is a valid object of class
"`projector`

".

### Usage

`is.projector(object)`

### Arguments

`object` |
The |

### Details

The function `is.projector`

tests whether the object consists of a
`matrix`

that is square, symmetric and idempotent. In checking
symmetry and idempotency, the equality of the matrix with either its
transpose or square is tested. In this, a difference in elements is
considered to be zero if it is less than `daeTolerance`

, which is
initially set to `.Machine$double.eps ^ 0.5`

(about 1.5E-08).
The function `set.daeTolerance`

can
be used to change `daeTolerance`

.

### Value

`TRUE`

or `FALSE`

depending on whether the object is a valid object of class
"`projector`

".

### Warning

The degrees of freedom are not checked. `correct.degfree`

can be used to check them.

### Author(s)

Chris Brien

### See Also

`projector`

, `correct.degfree`

in package dae.

`projector`

for further information about this class.

### Examples

```
## 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)
```

*dae*version 3.2.28 Index]