fmincon how can I solve it?

Why is it not working?

function [ J ] = objfun( x )

%Objective function

P=25.0231; E=2; h=2;

J=((P*h)/E)*(1/(X(1)+sqrt(2)*x(2)));

end

function [ c,ceq ]=myconfun22( x )

%Constraint functions

S=0.0092; P=25.0231;

c=[(P*(x(2)+sqrt(2)*x(1))/(sqrt(2)*(x(1)^2)+2*x(1)*x(2))))-17.5;
    (P/(x(1)+sqrt(2)*x(2)))-17.5*(1+0.1*S);
    (-P*x(2))/(sqrt(2)*(x(1)^2)+2*x(1)*x(2))+1.2;
    0.2-x(1);
    x(1)-6*(1+0.2)*S;
    0.2*(1-0.1*S)-x(2);
    x(2)-6];

ceq=[];

What should I do to get the optimized value?

[Walter Roberson]

You do not show your call to the optimizer. You also do not indicate what difficulties you are observing.

Answer 1

[John D'Errico]

I MIGHT postulate that had you looked carefully at your function, you might have seen that you used both X and x as the variable in this line.

J=((P*h)/E)*(1/(X(1)+sqrt(2)*x(2)));

MATLAB is case sensitive. Should it have known that X is intended to be the same as x? Surely if MATLAB did that, it would be the cause of some nasty bugs along the way.