MATLAB: Overload mtimes for double*char

charclassdoubleMATLABmtimesoperatoroverload

I am working on a Matlab class that handles numbers/matrices with physical units. I would like the user to be able to write the input as (double)*(char), like this:

L = 10*’m’  % L is ten meters long

This operation calls the mtimes function for the double class. I can easily overload this function and make it work as I want with respect to (double, char)-input, but I still want it to work normally for (double, double)-input. Using * inside the mtimes function with (double, double)-input simply refers the function back to itself, resulting in an infinite regression.

Can I modify the original double mtimes function, or how do I go about this?

Thanks

Best Answer

The short answer is DON'T DO THIS! There are many built-in MATLAB functions that do (double)*(char) operations and depend on getting double results. If you overload this operation with your own you will end up breaking a bunch of built-in MATLAB functions. (And also potentially breaking any other code you happen to download from others, such as from the FEX).

To answer your question directly, however, you can sometimes use the function named 'builtin' to do things like this (but DON'T DO IT for your proposed case!)

Related Solutions

MATLAB: Mtimes and transpose are being treated as a single function when used together

To circumvent this, my recommendation would be to overload mtimes in a subclass of type double.

classdef myclass < double                   
        methods
          function obj=myclass(data)      
              obj=obj@double(data);
          end
          function out = mtimes(a,b)
              out = myclass( a + b );
              disp('been in my-mtimes');
          end
        end
end

MATLAB: Using builtin assignment for classes that overload the assignment operator ‘=’

You are correct, your code does throw an error about recursion limits. However, I believe the operator you are interested in overloading is the subscripted assignment operator, "subsasgn". This will allow you to do:

obj.myProperty = value;

and call you own set function without receiving an error about the recursion limit. Here is what the class definition would look like:

classdef myClass < hgsetget
    properties
       myProperty
    end
    methods
      function mySetFunction(obj,value)
           obj.myProperty = value;
      end
         function a = subsasgn(a,s,b)
             if strcmp(s.subs,'myProperty')
                 mySetFunction(a,b);
             end
         end
      end
  end

Best Answer

Related Solutions

MATLAB: Mtimes and transpose are being treated as a single function when used together

MATLAB: Using builtin assignment for classes that overload the assignment operator ‘=’

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