isSymmetric {base} | R Documentation |

## Test if a Matrix or other Object is Symmetric

### Description

Generic function to test if `object`

is symmetric or not.
Currently only a matrix method is implemented.

### Usage

isSymmetric(object, ...)
## S3 method for class 'matrix':
isSymmetric(object, tol = 100 * .Machine$double.eps, ...)

### Arguments

`object` |
any **R** object; a `matrix` for the matrix method. |

`tol` |
numeric scalar >= 0. Smaller differences are not
considered, see `all.equal.numeric` . |

`...` |
further arguments passed to methods; the matrix method
passes these to `all.equal` . |

### Details

The `matrix`

method is used inside `eigen`

by
default to test symmetry of matrices ``up to rounding error'', using
`all.equal`

. It might not be appropriate in all
situations.

### Value

logical indicating if `object`

is symmetric or not.

### See Also

`eigen`

which calls `isSymmetric`

when its
`symmetric`

argument is missing, as per default.

### Examples

isSymmetric(D3 <- diag(3)) # -> TRUE
D3[2,1] <- 1e-100
D3
isSymmetric(D3) # TRUE
isSymmetric(D3, tol = 0) # FALSE for zero-tolerance

[Package

*base* version 2.5.0

Index]