# Documentation

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# isnan

Array elements that are NaN

## Syntax

`TF = isnan(A)`

## Description

`TF = isnan(A)` returns an array the same size as `A` containing logical 1 (`true`) where the elements of `A` are `NaN`s and logical 0 (`false`) where they are not. For a complex number `z`, `isnan(z)` returns `1` if either the real or imaginary part of `z` is `NaN`, and `0` if both the real and imaginary parts are finite or `Inf`.

For any real `A`, exactly one of the three quantities `isfinite(A)`, `isinf(A)`, and `isnan(A)` is equal to one.

## Examples

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Determine the `NaN` elements of the row vector, `A`.

```A = 0./[-2 -1 0 1 2] ```
```A = 0 0 NaN 0 0 ```
```TF = isnan(A) ```
```TF = 1×5 logical array 0 0 1 0 0 ```

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### Tall Array Support

This function fully supports tall arrays. For more information, see Tall Arrays.