# trace

Matrix trace.

## Syntax

* res = trace(x)

## Input argument

* x - a numeric value: scalar or matrix (double or single)

## Output argument

* res - a numeric value: a scalar

## Description

**trace(x)** computes the trace of x, the sum of the elements along the main diagonal.

## Example

```matlab
X = [1 0; 0 3];
Y = trace(X)
```

## See also

[eig](eig).

## History

| Version | Description     |
| ------- | --------------- |
| 1.0.0   | initial version |

## Author

Allan CORNET
