fmincon violates my constraints?

To be simple, my constraint function is like below:

function [ c, ceq ] = ctr( x, a, b)

[F] = f(x, a, b);

c(1) = -F;

ceq(1) = .....;

end

where x is the vector I'm going to optimize, and F is calculated through the function f, and I want to constraint F greater than 0. However, during the optimization using fmincon, the code crashes and saying "constraint function is not defined at ....", then I check my constraint function and found F is smaller than 0.

Could anyone explain why?

[Alan Weiss]

You didn't show us your nonlinear constraint code or your fmincon call. So how are we supposed to answer you?

Please give us real nonlinear constraint code, and your complete fmincon call, I mean something like

 [x,fval] = fmincon(fun,x0,A,b,Aeq,beq,lb,ub,nonlcon)

and give us the definitionse of your arguments, such as

 fun = @(x)objfun(x,a,b)

Alan Weiss

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