Assign Slider Value Changing to a vector element in App Designer

I want to have the input of a slider as an element of the vector f, in order to perform a matrix multiplication Kfinv*f. However Matlab keeps showing me the message "Incorrect dimension for matrix multiplications". How can I fix this?

I show you the code that I'm using in App Designer, the persistent variables are set in a previous ButtonPushed function

 % Value changing function: Slider
        function SliderValueChanging(app, event)
            persistent Ex Ey Kfinv u_c ind_dis Edof n D ndof
            Ex_dis=zeros(size(Ex)); Ey_dis=zeros(size(Ey)); 
            e_vm=zeros(n,1);
            e_vm_gp=zeros(4,1); 
            sx=zeros(n,1); sy=zeros(n,1); tau=zeros(n,1); f=zeros(100,1); 
            u=zeros(1,2*ndof);
            changingValue = event.Value;
            
            f(100)=changingValue; %Positioning
            u_fs=Kfinv*f; %Reduced solution vector

Answer 1

[Joel Van Sickel]

Hello Giovanni,

do you mean to multiply u_fs = Kfinv*f(changingValue)?

right now it is Kfinv*f, where f is [100x1].

that means Kfinv needs to b [mx100] in size, what size is Kfinv?

Regards,

Joel

[Giovanni Brambati]

I'm very sorry but I just noticed the the problem was not on the slider input but on the matrix Kfinv that was not stored correctly in a previous step, I will try to delete this question now.

Thank you