How can I troubleshoot this fmincon error?

Hello

I'm using the fmincon function to solve an optimization problem, but after the 2nd iteration(the first 2 runs fine), it gives me the following error:

Matrix dimensions must agree.

Error in finitedifferences

Error in computeFinDiffGradAndJac

Error in barrier

Error in fmincon (line 813)
    [X,FVAL,EXITFLAG,OUTPUT,LAMBDA,GRAD,HESSIAN] = barrier(funfcn,X,A,B,Aeq,Beq,l,u,confcn,options.HessFcn, ...

Error in ellipsoidOptimization (line 40)
[d,fval] = fmincon(volumefun, d0, [], [], [], [], lb , ub, nlcon)

I have no idea what to check.

[Torsten]

Nobody can tell without seeing your code.

[Richárd Tóth]

Can it be because my c array of nonlinear constraints have different size on the 2nd iteration ? In the first iteration it has 2 elements, on the 2nd it has 4. It has to have same size on every iteration?

[Torsten]

If you don't call fmincon anew for each iteration, c and ceq must have constant size.

[Richárd Tóth]

Okay I think that's the problem, I'll try to solve it, thanks