mustBeMatrix

R2026b

Validate that value is matrix

Since R2024b

Syntax

mustBeMatrix(value)

Description

mustBeMatrix(value) throws an error if value is not a matrix. A matrix is a two-dimensional array that has a size of m-by-n, where m and n are nonnegative integers. This function does not return a value. mustBeMatrix calls the ismatrix function to determine if the input is a matrix.

Class support: All numeric classes, logical, and MATLAB^® classes that overload ismatrix.

Examples

Determine If Value is Matrix

Use mustBeMatrix to validate that a value is a 2-D matrix.

Create a 3-D array and test whether it is a matrix. Because the array has more than two dimensions, mustBeMatrix throws an error.

a = ones(2,3,2);
mustBeMatrix(a)

Value must be a matrix.

Validate That Function Input Is Numeric Matrix

Use an arguments block to restrict the function input to a numeric matrix using mustBeMatrix and mustBeNumeric.

The WeeklyTotals function sums the columns of the input matrix. If the input is empty ([]), the sum is returned as zero.

function r = WeeklyTotals(DailyTotals)
    arguments
        DailyTotals {mustBeMatrix, mustBeNumeric}
    end
    if isempty(DailyTotals)
        r = 0;
    else
        r = sum(DailyTotals,1);
    end
end

An alternative way to validate the inputs is with the arguments block

arguments
    DailyTotals (:,:) {mustBeNumeric}
end

However, the use of (:,:) leads to automatic size conversion of the input into a 2-D matrix. mustBeMatrix is stricter because it throws an error when the input has more than two dimensions.

Call the WeeklyTotals function with a magic square matrix.

W = magic(4);
r = WeeklyTotals(W)

r =

    34    34    34    34

Input Arguments

value — Value to validate

scalar | vector | matrix

Value to validate, specified as a scalar, vector, or matrix.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | char | string | struct | table | cell | categorical | datetime | duration | calendarDuration
Complex Number Support: Yes

Extended Capabilities

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

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

GPU Arrays

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

The mustBeMatrix 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™.

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

Version History

Introduced in R2024b

R2025a: Code generation support

You can generate C/C++ code for the mustBeMatrix function.