isSymmetric-methods {Matrix} | R Documentation

## Methods for Function isSymmetric in Package 'Matrix'

### Description

`isSymmetric(M)` returns a `logical` indicating if `M` is a symmetric matrix. This (now) is a base function with a default method for the traditional matrices of `class` `"matrix"`. Methods here are defined for virtual Matrix classes such that it works for all objects inheriting from class `Matrix`.

### See Also

`forceSymmetric`, `symmpart`, and the formal class (and subclasses) `"symmetricMatrix"`.

### Examples

    isSymmetric(Diagonal(4)) # TRUE of course
    M <- Matrix(c(1,2,2,1), 2,2)
    isSymmetric(M) # TRUE (*and* of formal class "dsyMatrix")
    isSymmetric(as(M, "dgeMatrix")) # still symmetric, even if not "formally"
    isSymmetric(triu(M)) # FALSE

    ## Look at implementations:
    showMethods("isSymmetric", includeDefs=TRUE)# "ANY": base's S3 generic; 6 more

[Package Matrix version 1.2-7.1 Index]