Attempted to access x(10); index out of bounds because numel(x)=2.

Hello, I'm trying to solve a non linear optimization problem. And I get this error. I have no idea what is happening.

objfun:

    function f = objfun(x)
    f = 76500*x(1)*x(2);

confun:

    function [c, ceq] = confun(x)
    % Nonlinear inequality constraints
    c = [0.0075-x(1)*x(2)^2;   0.000066425-x(1)*x(2)^3;   0.04-x(10);   x(1)-0.12;   0.06-x(2);
        x(2)-0.2;   x(1)-x(2)];
    % Nonlinear equality constraints
    ceq = [];

Command Window:

    >> x0=[0.04 0.060];
    >> options = optimoptions(@fmincon,'Algorithm','sqp');
    >> [x,fval] = fmincon(@objfun,x0,[],[],[],[],[],[],@confun,options);

output

Attempted to access x(10); index out of bounds because numel(x)=2.

    Error in confun (line 3)
    c = [0.0075-x(1)*x(2)^2;   0.000066425-x(1)*x(2)^3;   0.04-x(10);   x(1)-0.12;   0.06-x(2);

    Error in fmincon (line 651)
            [ctmp,ceqtmp] = feval(confcn{3},X,varargin{:});

Caused by: Failure in initial user-supplied nonlinear constraint function evaluation. FMINCON cannot continue.

Answer 1

[Geoff Hayes]

Kaushik - your confun function is defined as

 function [c, ceq] = confun(x)

 % Nonlinear inequality constraints
 c = [0.0075-x(1)*x(2)^2;   0.000066425-x(1)*x(2)^3;   0.04-x(10);   x(1)-0.12;   0.06-x(2); ...
      x(2)-0.2;   x(1)-x(2)];

 % Nonlinear equality constraints
 ceq = [];

Note how in all cases except one, you reference x(1) or x(2). Do you really mean to use x(10)? The error message is telling you that your input vector x has only two elements, yet third element of c is initialized using x(10). Is this intentional or is it a typo and should be x(1) instead?

[kxs143130]

Oh. I did update that. But got the same error.

[Geoff Hayes]

There must be a different error message if you changed the x(10) to x(1). Please copy and paste the full error message to this thread.