Validate that the result of an operation is numeric.

mustBeNumeric(5 < 10)

Error using mustBeNumeric (line 10)
Values must be numeric.

The relational operator for less than returns a logical value.

This class restricts the value of Prop1 to numeric values.

classdef MyClass
   properties
      Prop1 {mustBeNumeric}
   end
end

Create an object and assign a value to its property.

obj = MyClass;
obj.Prop1 = isprime(29);

Error setting 'Prop1' property of 'MyClass' class:
Values must be numeric.

When you assign a value to the property, MATLAB^® calls mustBeNumeric with the value being assigned to the property. mustBeNumeric issues an error because the value assigned to Prop1 is a logical.

function r = mbNumeric(x)
    arguments
        x (1,:) {mustBeNumeric}
    end
    p = [3 2 1];
    r = polyval(p,x);
end

Calling this function with a character vector results in an error being thrown by mustBeNumeric.

x = '4 3 2';
r = mbNumeric(x);

Error using mbNumeric
Invalid input argument at position 1. Value must be numeric.