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

Question

kxs143130 2015-1-17

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/170374-attempted-to-access-x-10-index-out-of-bounds-because-numel-x-2

评论： Geoff Hayes 2015-1-18

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.

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Answer 1

Geoff Hayes 2015-1-17

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/170374-attempted-to-access-x-10-index-out-of-bounds-because-numel-x-2#answer_165160

在 MATLAB Online 中打开

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?