`mustBeScalarOrEmpty`

Checks that a value is a single element or has none.

Category: Programming > Functions

Syntax

mustBeScalarOrEmpty(A)

Checks that A is a scalar or is empty. Returns nothing if the check passes and throws an error if not.

Description

mustBeScalarOrEmpty is a validator: it inspects its input and either returns silently or raises an error with the identifier MATLAB:validators:mustBeScalarOrEmpty. The error message states the requirement that was violated, so the caller sees what was expected rather than a generic failure.

Useful for optional arguments, where [] means 'not provided' and a scalar means 'use this value'.

Input arguments

A: The value to check. Any array of the class the validator accepts.

Example

Passing and failing input

mustBeScalarOrEmpty(5);
disp('passed')
try
    mustBeScalarOrEmpty([1 2])
catch err
    disp(err.message)
end

Output

passed
Value must be scalar or empty.

See also

isscalar isempty mustBeNonempty mustBeVector