## ISNAN Test for Not-a-Numbers

Section: Inspection Functions

### Usage

Returns true for entries of an array that are NaN's (i.e., Not-a-Numbers). The usage is

       y = isnan(x)

The result is a logical array of the same size as `x`, which is true if `x` is not-a-number, and false otherwise. Note that for `complex` or `dcomplex` data types that the result is true if either the real or imaginary parts are NaNs.

### Example

Suppose we have an array of floats with one element that is `nan`:

    --> a = [1.2 3.4 nan 5]

    a =

        1.2000    3.4000       nan    5.0000

    --> isnan(a)

    ans =

     0 0 1 0