I am attempting to implement the fminunc (unconstrained Problem) function in MATLAB. I am getting an error with my code.

Objective Function

function r = objfn(x)

x1 = x(1); x2 = x(2);     %two design variables
n = size(x1);

     for i = 1:n
   r(i) = exp((-1.767767*(x1 - x1(i)).^2)+(-1.0511218*(x2-x2(i)).^2)); 
         % this is my equation, where r is a vector matrix of order 25X1
  end

     a = r' 
   y = -0.0293 + (a*(G1)); %G1 is a matrix of order 

fminunc

% bounds
     Lb = [6; 12]; Ub = [8; 15];
    x0 = [6.1; 13]; % initial value

        x = fminunc(fun,x0)

when i execute i get this error

" Attempted to access x1(2); index is out of bounds because numel(x1) = 1"

I think i have an error in my loop, please help me to rectify it and get the solution, i am new to coding

Answer 1

[Alan Weiss]

Your code does not make much sense to me for the following reasons:

• x1 and x2 are scalars. So what do you expect n to be?
• Since x1 is a scalar, there is no x1(2), and that is the error you get. What did you want x1(2) to be?
• Did you pass the matrix G1 to your objective function somehow, or is there a nested function that we cannot see?

I suggest that you put a breakpoint in your code and use the debugger.

Alan Weiss

MATLAB mathematical toolbox documentation