# lower.tri

##### Lower and Upper Triangular Part of a Matrix

Returns a matrix of logicals the same size of a given matrix with
entries `TRUE`

in the lower or upper triangle.

- Keywords
- array

##### Usage

```
lower.tri(x, diag = FALSE)
upper.tri(x, diag = FALSE)
```

##### Arguments

- x
a matrix or other R object with

`length(dim(x)) == 2`

. For back compatibility reasons, when the above is not fulfilled,`as.matrix(x)`

is called first.- diag
logical. Should the diagonal be included?

##### See Also

`diag`

, `matrix`

; further `row`

and `col`

on which `lower.tri()`

and
`upper.tri()`

are built.

##### Examples

`library(base)`

```
# NOT RUN {
(m2 <- matrix(1:20, 4, 5))
lower.tri(m2)
m2[lower.tri(m2)] <- NA
m2
# }
```

*Documentation reproduced from package base, version 3.5.1, License: Part of R 3.5.1*

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