# ismatrix

Determine whether input is matrix

## Syntax

``TF = ismatrix(A)``

## Description

example

````TF = ismatrix(A)` returns logical `1` (`true`) if `A` is a matrix. Otherwise, it returns logical `0` (`false`). A matrix is a two-dimensional array that has a size of m-by-n, where m and n are nonnegative integers.```

## Examples

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Determine whether arrays of different sizes are matrices.

Create an array of size 1-by-3. Determine whether it is a matrix.

```A1 = zeros(1,3); TF = ismatrix(A1)```
```TF = logical 1 ```

Create an empty array of size 0-by-3. Determine whether it is a matrix. A 2-D empty array is a matrix.

```A2 = zeros(0,3); TF = ismatrix(A2)```
```TF = logical 1 ```

Create an array of size 1-by-3-by-2. Determine whether it is a matrix. A 3-D array is not a matrix.

```A3 = zeros(1,3,2); TF = ismatrix(A3)```
```TF = logical 0 ```

Create a 3-D array and determine whether the array elements are a matrix.

First define a 2-D array of size 2-by-3. Determine whether it is a matrix.

`A = [0.1 0.2 0.5; 0.3 0.6 0.4]`
```A = 2×3 0.1000 0.2000 0.5000 0.3000 0.6000 0.4000 ```
`TF = ismatrix(A)`
```TF = logical 1 ```

To create a 3-D array, add a third dimension to the array `A`. Assign another 2-by-3 matrix to the third dimension of `A` with index value 2.

`A(:,:,2) = ones(2,3)`
```A = A(:,:,1) = 0.1000 0.2000 0.5000 0.3000 0.6000 0.4000 A(:,:,2) = 1 1 1 1 1 1 ```

Check whether the 3-D array of size 2-by-3-by-2 is a matrix.

`TF = ismatrix(A)`
```TF = logical 0 ```

Now determine whether the array elements of `A` are a matrix. Check whether the second page of the 3-D array is a matrix. The syntax `A(:,:,2)` uses a colon in the first and second dimensions to access all rows and all columns.

`TF = ismatrix(A(:,:,2))`
```TF = logical 1 ```

Check whether the second row of the 3-D array is a matrix. The syntax `A(2,:,:)` uses a colon in the second and third dimensions to include all columns and all pages.

`TF = ismatrix(A(2,:,:))`
```TF = logical 0 ```

`A(:,:,2)` is a matrix since it is a multidimensional array of size 2-by-3. However, `A(2,:,:)` is not a matrix since it is a multidimensional array of size 1-by-3-by-2.

Create an array of characters. Determine whether it is a matrix.

```A = 'Hello, World!'; TF = ismatrix(A)```
```TF = logical 1 ```

Check the dimension of `A` using `size`. `A` is a matrix of size 1-by-13.

`size(A)`
```ans = 1×2 1 13 ```

Now create a string scalar by enclosing a piece of text in double quotes.

`A = "Hello, World!";`

Check whether the scalar `A` of size 1-by-1 is also a matrix.

`TF = ismatrix(A)`
```TF = logical 1 ```

## Input Arguments

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Input array, specified as a scalar, vector, matrix, or multidimensional array.

## Version History

Introduced in R2010b