tr {psych} | R Documentation |

## Find the trace of a square matrix

### Description

Hardly worth coding, if it didn't appear in so many formulae in psychometrics, the trace of a (square) matrix is just the sum of the diagonal elements.

### Usage

```
tr(m)
```

### Arguments

### Details

The tr function is used in various matrix operations and is the sum of the diagonal elements of a matrix.

### Value

The sum of the diagonal elements of a square matrix.

i.e. tr(m) <- sum(diag(m)).

### Examples

```
m <- matrix(1:16,ncol=4)
m
tr(m)
```

[Package *psych* version 2.3.6 ]