ismatrix

Determine whether input is matrix

Syntax

TF = ismatrix(A)

Description

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

Arrays of Different Sizes

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

Determine Matrix from Three-Dimensional Array

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.

Determine Matrix from Character Vector and String

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

A — Input array

scalar | vector | matrix | multidimensional array

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

Extended Capabilities

Tall Arrays

Calculate with arrays that have more rows than fit in memory.

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

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

GPU Arrays

Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

The ismatrix function fully supports GPU arrays. To run the function on a GPU, specify the input data as a gpuArray (Parallel Computing Toolbox). For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).

Distributed Arrays

Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

This function fully supports distributed arrays. For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).

Version History

Introduced in R2010b