From: Alan_Weiss <>
Newsgroups: comp.soft-sys.matlab
Subject: Re: Non linear optimization problem
Date: Tue, 10 Sep 2013 09:30:14 -0400
Organization: MathWorks
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On 9/10/2013 12:04 AM, Bozorgmehr wrote:
> Hi all
> I am trying to solve a Maximum Likelihood estimation. I tried fminnunc 
> function in matlab optimization toolbox. However, there is an error:
> Error using optimfcnchk (line 288)
> FUN must be a function, a valid string expression, or an inline 
> function object.
> Error in fminunc (line 239)
>   funfcn = 
> optimfcnchk(FUN,'fminunc',length(varargin),funValCheck,gradflag,hessflag);
> My objective function is quite complicated. I have to write for loop 
> in my function to sum likelihoods. However,when I call objective 
> function, there is no error, and for x0 I have a very quick answer.
> My variable,X, which should be optimized, is a matrix. In first lines 
> of my objective function, I defined new variables, using X. For 
> instance, I defined nu=x(1,1), and used "nu" rather than x(1,1) in 
> objective function. Is this ok?
> Could you please help me?
> Thanks

I'm sorry, but you have not given us enough information to diagnose what 
is going wrong. Please give the following:
* Your function call, something like
[x,fval] = fminunc(@myfun,x0,options);
Also, and this is important, the first line of your objective function, 
something like
function fval = myfun(x)
* Your options, something like
options = optimset('Algorithm','quasi-newton');
* The entire error listing, not just one line of it.

Alan Weiss
MATLAB mathematical toolbox documentation