values of equation in last iteration in fmincon

I optimize a problem maximizing EU1 with the fmincon solver..the code below is the objective function i insert in fmincon instruction ...

can i somehow get the value of xw1 equation in last itteration??

function EU1 = eq_obj1(LW_ini,LG_obs,LVmat,LLand,rc,X) 

EU1=0;
xw1=0;

for i=1:1:length(rc)
    if (LLand(rc(i)))
        xw1=xw1+LG_obs(rc(i))*X(i);
    end
end
xw1=LW_ini+xw1;
% xw1
% class(xw1)

for i=1:1:length(rc)
    for j=1:1:length(rc)
       EU1=EU1+LVmat(i,j)*X(i)*X(j); 
    end    
end

EU1=xw1-0.5*EU1/xw1;
%EU1=-EU1;
xw1;

Answer 1

[A. Sawas]

After the fmincon is run and you got the solution vector, make a call to the objective function using the solution vector but in this time add/enable the code in the objective function to display the values you want.

For example assuming you called fmincon like this:

eq_obj = @(x)eq_obj1(LW_ini,LG_obs,LVmat,LLand,rc,x);
[x] = fmincon(eq_obj,x0,A,b);

Edit the objective function to display the value of xw1; then call the objective function:

eq_obj(x);

[Takis Tsoukalas]

first of all thanks the quick response..if i display xw1 in the objective function then i am gonna get its value for all iterations for fmincon and one more time for running eq_obj(x);

[Catalytic]

Instead of displaying xw1, provide the option of returning it

function [EU1,xw1] = eq_obj1(LW_ini,LG_obs,LVmat,LLand,rc,X) 

[A. Sawas]

Catalytic : I agree that will be a better workaround.

Answer 2

[Matt J]

The computation of xw1 is a trivial one-liner. Just compute it separately from the optimal X given to you by fmincon,

xw1=sum( LG_obs(rc).*LLand(rc).*Xoptimal) + LW_ini

[Matt J]

Naturally also, i would encourage you to simplify your objective function in a similar way to make it more efficient

function EU1 = eq_obj1(LW_ini,LG_obs,LVmat,LLand,rc,X) 


  xw1=sum( LG_obs(rc).*LLand(rc).*X) + LW_ini;

  EU1=xw1-0.5*(X(:).'*LVmat*X(:))/xw1;
  

end

[A. Sawas]

The only drawback I guess of computing the value of xw1 outside the objective fuction will be the need to edit two locations if the equation has changed.

[Matt J]

Then create a dedicated function to compute xw1 and call that function in the objective as well as everywhere else xw1 is needed,

function xw1=getxw1(LW_ini,LG_obs,LVmat,LLand,rc,X);

   xw1=sum( LG_obs(rc).*LLand(rc).*X) + LW_ini;

end

function EU1 = eq_obj1(LW_ini,LG_obs,LVmat,LLand,rc,X) 


  xw1=getxw1(LW_ini,LG_obs,LVmat,LLand,rc,X);
  
  EU1=xw1-0.5*(X(:).'*LVmat*X(:))/xw1;
  
end