Custom Display for symbolic Object

Hello,

I do alot of work with symbolic variables and latex, and I would like to have some custom output for when a semi colon is not put at the end of a line, I would like it to output the formated version of the symbolic variable so that I can use the copy as LaTeX. An example of how I would like it displayed is below, when I run the line sigma_i = 10*u.MPa I would like it to be displayed as if I had run myFunc.

u =symunit;

sigma_i =10*u.MPa

sigma_i = 

myFunc(sigma_i)

function myFunc(inputValue)
varName =  inputname(1);
symbolicVarName = sym(varName);
disp(vpa(symbolicVarName == inputValue, 3));  % Adjust the precision as needed
end

I have tried creating class MySym which inherits from sym but whenever I do any operations the output ends up being a sym

classdef MySym < sym
    methods
        % Constructor method
        function obj = MySym(val)
            % Convert input to sym and store it in the object
            obj = obj@sym(val);  % Call superclass constructor
        end
        % Custom display method
        function display(obj)
            varName = inputname(1);
            if isempty(varName)
                varName = 'ans';
            end
            symbolicVarName = sym(varName);
            disp(vpa(symbolicVarName == obj, 3));  % Display with 3 digits precision
        end
        
    end
end

[Walter Roberson]

disp(latex(vpa(symbolicVarName == obj, 3)));

perhaps ?

Answer 1

[Shishir Reddy]

Hi Justin

To achieve the behavior where a symbolic variable automatically displays its formatted LaTeX representation when a semicolon is omitted, a custom class can indeed be created that extends sym. However, to ensure that operations on instances of the new class return instances of the same class (rather than reverting to sym), the arithmetic operations and other relevant methods has to be overidden.

The following methods could be incorporated in the MySym class to ensure the output doesn't end up being a sym.

% Override arithmetic operations to return MySym objects
function result = plus(a, b)
    result = MySym(plus@sym(a, b));
end

function result = minus(a, b)
    result = MySym(minus@sym(a, b));
end

function result = mtimes(a, b)
    result = MySym(mtimes@sym(a, b));
end
        
function result = mrdivide(a, b)
    result = MySym(mrdivide@sym(a, b));
end
        
function result = mpower(a, b)
    result = MySym(mpower@sym(a, b));
end

Similarly, more methods can be added as per requirement.

This setup should ensure that any operations involving MySym instances return results that are also MySym instances, allowing for consistent behavior across all the calculations.

For more information regarding sym, kindly refer the following documentation -

https://www.mathworks.com/help/symbolic/sym.html

I hope this resolves the issue.