The number of rows in A must be the same as the number of elements of b.

%% Discrete modelling 
Ae=(1-(K*ts)/Cth);
Be=(ts*COP*HP)/Cth;
D=ts*K/Cth;
Tin=zeros(1,i);
u=zeros(1,i);

for j=1:i
    
%     f=@(u) sum(u(j)*gamma(j));
      f=u(j); 
    %%%Starting point%%%
    u0=0;
    if j>1
        Tin(j+1)=Ae*Tin(j)+Be*u(j)+D*Tout(j);
    else
        Tin(j)=0;
    end

    %%%Constraints%%%
    %%%Equality%%%%
    Aeq=Be;
    beq=(Tin(j+1)-Ae*Tin(j)-D*Tout(j));

    
    %%%Inequality%%%
    A=[(Tin(j)*Be)/(Tin(j+1)-Ae*Tin(j)-D*Tout(j)) ;(-(Tin(j)*Be)/(Tin(j+1)-Ae*Tin(j)-D*Tout(j)))];
    b=[Tmax ; -Tmin];

    
    options = optimoptions(@linprog,'Display', 'off');
    
    u(j)=linprog(f,u0,A,b,Aeq,beq,umin,umax,options);

end    

I am getting the error: The number of rows in A must be the same as the number of elements of b.

Does anyone know why?

Thanks!

[Adam Danz]

Please provide the entire error message and indicate which line the error comes from (most likely from the line containing linprog()).

"Does anyone know why? "

Yes, because the number of rows of 'A' (size(A,1)) is not the same as the number elements in 'b' (numel(b)).

[Ricardo López]

Error using linprog (line 232)

The number of rows in A must be the same as the number of elements of b.

Error in newdata (line 71)

u(j)=linprog(f,u0,A,b,Aeq,beq,umin,umax,options);

>> numel(b)

ans =

2

>> size(A,1)

ans =

2

That is why I am asking why I am getting that

[Walter Roberson]

We cannot tell. There are too many variables that you do not show us the size of.

Look at size(A) and size(b) and look at the size of the variables used to construct A and b

[Ricardo López]

i=1008,

size(Tout) is 1 1008

umin, umax Tmin Tmax sizes are 1 1.

Ae, Be, D are also constants.

Thanks!

Answer 1

[Walter Roberson]

MATLAB function calls use positional parameters, not named parameters. The second parameter you are passing, u0, is getting received in the slot where the linear constraints matrix is expected, so you are setting your constraints matrix to scalar 0. Your variable named A is being received in the linear constraints outcome vector, and has two elements, which is not the same as the number of rows of your scalar u0.

Your u0 parameter should not be present.