Fmincon problems with A and b matrices that differ depending on for loop

Hi

Im doing a nonlinear optimization using fmincon that includes nonlinear equality constraints linear inequality constraints (These depend on values from two excel spreadsheets.

This is my code for the A and b matrices for j=1:3 for i=1:5

        L = xlsread('hourly electric demand.xlsx');
        Lth = xlsread('hourly thermal demand.xlsx');

        if xin(1)>= L(j,i) &&  xin(2)>=Lth(j,i);

             A(1,:)=[FIT RHI 0 0 -(FIT-Xe);-1 0 -1 0 0; 0 -1 0 -1 0];

             b = [max(Pe*L(j,i))+Pth*max(Lth(j,i))+ Operation; -L(j,i);...
                 -Lth(j,i)];

        elseif xin(1)<=L(j,i) &&  xin(2)<=Lth(j,i);

           A(2,:)=[FIT RHI -Pe -Pth 0;-1 0 -1 0 0; 0 -1 0 -1 0];

          b = [max(Pe*L(j,i)+Pth*Lth(j,i))+ Operation;-L(j,i); -Lth(j,i)];

        elseif xin(1)>=L(j,i) &&  xin(2)<=Lth(j,i);

            A(3,:)=[FIT RHI 0 -Pth -(FIT-Xe);-1 0 -1 0 0; 0 -1 0 -1 0];

            b = [max(Pe*L(j,i)+Pth*Lth(j,i))+ Operation; -L(j,i); -Lth(j,i)];

        elseif xin(1)<= L(j,i) &&  xin(2)>= Lth(j,i);

            A(4,:)=[FIT RHI -Pe -Pth 0;-1 0 -1 0 0; 0 -1 0 -1 0];

      b = [max(Pe*L(j,i)+Pth*Lth(j,i))+ Operation; -L(j,i); -Lth(j,i)];

        end

    end
end

and this is the code for the objective function

      f =  sum(((0.537*(L(j,i)-xin(1)))+(0.185*(Lth(j,i)-xin(2)))));

However I am getting the following error

??? Subscripted assignment dimension mismatch.

Error in ==> invoke at 42 A(1,:)=[FIT RHI 0 0 -(FIT-Xe);-1 0 -1 0 0; 0 -1 0 -1 0];

Do I need to make changes to the objective function since it only includes xin(1) and xin(2) whereas I am constraining to 5 difference xin?

thanks

Answer 1

[Walter Roberson]

[FIT RHI 0 0 -(FIT-Xe);-1 0 -1 0 0; 0 -1 0 -1 0] is clearly 2 dimensional, but you are trying to assign it to a vector A(1,:) . That isn't going to work.

[Andrew Alkiviades]

Thanks Walter

I have confused myself quite a bit (and with some basic maths)

do you have any suggestions on solving this issue?

thanks again

Answer 2

[Andrew Alkiviades]

Thanks Walter

I have confused myself quite a bit (and with some basic maths)

do you have any suggestions on solving this issue?

thanks again

[Walter Roberson]

Consider that if you have an if/elseif structure that if the first branch is executed then the second branch never can be. Your code can therefore set only _one_ of A(1,:) or A(2,:) etc. Perhaps you should be assigning to _all_ of A ?

[Andrew Alkiviades]

Could I not just leave it as A = and b = for all the 4 different ifs and elseifs since each if statement requires different values in the A matrix. Therefore just remove the A(1,:) etc?

Thanks Walter

p.s just a beginner it Matlab - sorry for the basic questions !

[Walter Roberson]

I suspect so, removing the (1,:) etc.

[Andrew Alkiviades]

Thanks, I have tried that... Next question :)

i cant seem to find this error anywhere online.

??? Undefined function or method 'isfinite' for input arguments of type 'cell'.

Error in ==> C:\Program Files\MATLAB\R2010b\toolbox\optim\optim\barrier.p>barrier at 24

Do you have any idea what this may be?

Possibly in calling fmincon? which has been done by

options = optimset('Display', 'iter', 'Algorithm','interior-point');

[x,fval,exitflag]=fmincon(@myobjective,x0,A,b,[],[],lb,[],@confun2, options)