MATLAB: How to make user-defined type pass as numeric

Question

Suppose I have a defined type that behaves like a number. I would like it to pass the test:

validateattributes(x, {'numeric'}, {})

It's not enough, apparently, to overload the function isnumeric.m. What else needs to be done?

Thanks, n

Answer 1

Naor - try overloading the isa function instead. For example, let's suppose that the following class is "numeric".

classdef MyNumberClass
   properties
      x
   end
   methods
        function obj = MyNumberClass(varargin)
           if nargin > 0
              obj.x = 42;
           else
              obj.x = 99;
           end
        end
        function [result] = isa(obj,typeStr)
           result = false;
           if strcmpi(typeStr,'numeric') || strcmpi(typestr,'MyNumberClass')
              result = true;
           end
        end
     end
  end

Then in the Command Window, try the following

 myInstance = MyNumberClass;

Now try to validate it as

 validateattributes(myInstance, {'numeric'}, {})

No error is thrown and so the object is considered to be numeric. Note that you would need to overload isnumeric so that that function "passes" too.