MATLAB Function Reference |

**Syntax**

**Description**

```
TF = isnan(A)
```

returns an array the same size as `A`

containing logical true (`1`

) where the elements of `A`

are `NaN`

s and logical false (`0`

) 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**

a = [-2 -1 0 1 2] isnan(1./a) Warning: Divide by zero. ans = 0 0 0 0 0 isnan(0./a) Warning: Divide by zero. ans = 0 0 1 0 0

**See Also**

ismethod | isnumeric |

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