cant get object's method to return multiple outputs

Hi, i cant get my method to return multiple outputs.

I have my object folder with the classdef

classdef crm < handle

%...

methods (Access = public)

[Tout,Yout]=runTimeDependent(self,n_0,tdata,nedata,Tedata)

end

end

And my function definition in a separate file inside the @crm folder

function [Tout,Yout]=runTimeDependent(self,n_0,tdata,nedata,Tedata)

TSPAN = [tdata(1) tdata(end)];

[Tout,Yout]=ode15s(@odefun,TSPAN,n_0);

function dydt=odefun(t,y)

% ... ode function here

end

end

If i build my object and run the method everything works but if i ask 2 outputs i get an error

c=crm();

% definemy parameters ( Y0, t, ne, Te)

c.runTimeDependent(Y0,t,ne,Te); % This line works

[Tout, Yout] = c.runTimeDependent(Y0,t,ne,Te); %this line throws an error

Only when i ask both my outputs do i get an error

Error using indexing

Too many output arguments.

Error in test_timedep (line 4)

[Tout, Yout] = c.runTimeDependent(Y0,t,ne,Te);

[Walter Roberson]

It would be interesting to see the output of

[Tout, Yout] = runTimeDependent(c,Y0,t,ne,Te);

and of

[Tout] = c.runTimeDependent(Y0,t,ne,Te);

[vanni meier]

EDIT:

The first case is working. is there a way to call this function in the traditional c.method() way and get it to work?

In the second case you get the vector of times Tout, at which the ode was solved.

If you are wondering, ode15s() sucessfully returns both Tout and Yout. Only runTimeDependent() fails to return multiple outputs.

Answer 1

[Steven Lord]

From the error message I suspect the class overloads indexing, either by overloading subsref or using one or more of the indexing mixins (specifically the matlab.mixin.indexing.RedefinesDot Class). Is that correct? If so, does the class overload either of the methods dotListLength or dotReference or does it inherit from either of the classes matlab.mixin.indexing.ForbidsPublicDotMethodCall, or matlab.mixin.indexing.OverridesPublicDotMethodCall method to handle the case where the "reference" is actually a call to a class method?

[vanni meier]

Correct, the class overloads subref. Althoug I'm not the autor of this portion of code so I guess i need to go read documentation on that. dotListLength and dotReference are not overloaded.

Just in case, here is the subrefs method

function result = subsref(self, s) % Overload indexing in order to use names as indices

    % The struct s contains the location and inputs where a () was called
    for i = 1:length(s)
        % Treat different types of inputs separately: numbers, text or vectors like 3:7
        if iscell(s(i).subs)
            for j = 1:length(s(i).subs)
                if ischar(s(i).subs{j})
                    labels(j) = string(s(i).subs{j}); %string(s(i).subs{:});
                else
                    labels(j) = 0; % Do not modify non-char inputs
                end
            end
        else
            labels = string(s(i).subs);
        end

        % Find all instances when an index corresponds to a name
        names = [self.name];
        isName = zeros(1,length(labels));
        for j = 1:length(labels)
            if any(strcmpi(labels(j),names))
                isName(j) = 1;
            end
        end

        % Convert them to integer index
        if (any(isName)) 
            for j = find(isName) % % Loop over all name occurrences 1:length(labels)
                s(i).subs(j) = {self.getname(labels(j))}; 
            end
        end
    end
    
    % The modified inputs are given to the default () handler
    try 
        result = builtin('subsref', self, s);
    catch
        builtin('subsref', self, s);
    end
end

[Steven Lord]

Set a breakpoint in that function then run this command:

[Tout] = c.runTimeDependent(Y0,t,ne,Te);

You should see that MATLAB will stop at the breakpoint in the class's subsref method.

Your subsref should probably be implemented with varargout as an output argument, and when subsref invokes one of the class's methods it should use the technique shown in the "Assigning to a Comma-Separated List" section on this documentation page. You may also need to overload the numArgumentsFromSubscript method; see the second example on that documentation page for an example of a class that both overloads that method and has a subsref overload returning varargout.