MATLAB: App Designer and external function

Question

Im having issues with running my app. The m file alone works but, when I attempt to convert it to the app, its throwing errors just in the app. My code involves matrixes and vectors. Error is at the external function ElementofFasteners, I have commented the lines for a visual representation of what I am seeing. Like I said, this works as a standalone m. file without the app. What am I missing and are the app.inputs creating different variables or… need a bit of help

Error using /

Matrix dimensions must agree.

Error in Fasteners (line 29)

c1=(((t1 + t2)/(2*D))^a);

% Button pushed function: SolveButton
        function SolveButtonPushed(app, event)
            %Solve Everything here
            app.FastF1.Value = numfast(app.nf); % numfast external function-works 
            app.FastF2.Value = app.E1;
            app.FastF3.Value = app.d3;
            
            app.nnel = 3 * app.nf;
            app.nnode = 2 + (2 * app.nf);
            app.sdof = app.nnode * app.ndof;
            
            kk=zeros(app.sdof,app.sdof);    
            index=zeros(app.nel*app.ndof,1);  %orange underline (use Plate(app.,..
            for iel=1:app.nnel           
                
                if iel <= (app.nnel - app.nf)
                    [k]=Plate(app.E1,app.w,app.t1,app.L); % Plate external function-orange underline (use Plate(app.,.. 
                    index = ElementdofPlate(iel,app.nel,app.ndof,app.nf);
                else
                    if app.count == 1
                        d = app.d2;
                        app.count = app.count + 1;
                    elseif app.count == 2
                        d = app.d3;
                        app.count = app.count + 1;
                    elseif app.count == 3
                        d = app.d4;
                        app.count = app.count + 1;
                    elseif app.count == 3
                        d = app.d5;
                        app.count = app.count + 1;
                    elseif app.count == 4
                        d = app.d6;
                        app.count = app.count + 1;
                    else
                        d = app.d1;
                        app.count = app.count + 1;
                    end
                    [k]=Fasteners(app.E1,app.E2,app.E3,app.t1,app.t2,d); % Fastners external function-orange underline (use Fasteners(app.,.. 
                    index = ElementdofFasteners(iel,app.nf); %  external function-orange underline (use Elemt..(app.,.. 



                end
                
                kk=Assemble(kk,k,index); % external function-orange underline (use Elemt..(app.,.. 
            end
            %
            % Applying the Boundary conditions
            [kk] = constraints(kk,1) ;%  external function-orange underline (use Elemt..(app.,.. 
            [kk] = KRED(kk,app.nnode);%  external function-orange underline (use Elemt..(app.,.. 
            [uu] = Displacements(kk,app.P,app.nnode); %  external function-orange underline (use Elemt..(app.,.. 
            app.FastF4.Value = uu(1);
            

Answer 1

Check the order of the callbacks