# isletter

Determine which characters are letters.

## Syntax

* res = isletter(str)

## Input argument

* str - scalar, vector, matrix or multidimensional array.

## Output argument

* res - logical array

## Description

**isletter** determines which characters are letters.

## Examples

```matlab
isletter('Nel Son')
```

```matlab
isletter("六書 six writings")
```

## See also

[toupper](toupper).

## History

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

## Author

Allan CORNET
