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From: panos on 3 Jun 2006 07:26
Hi, all

i have a problem in fmincon. i just want to optimize a cost function
for a simple compressor-turbine system. the strange thing that
happens is that when it converges (if it converges) i receive the
same values i put at the lower boundaries for the 3rd and the 5th
variable. for example

var0=...
lb=[0,1,2,3,4];
ub=...
..
..
..
i get the results from the optimization
[..,..,2,..,4]

if you have experienced something like that or you know what goes, i
would appreciate some feedback

Thanks
From: John D'Errico on 3 Jun 2006 07:33
panos wrote:
>
>
> Hi, all
>
> i have a problem in fmincon. i just want to optimize a cost
> function
> for a simple compressor-turbine system. the strange thing that
> happens is that when it converges (if it converges) i receive the
> same values i put at the lower boundaries for the 3rd and the 5th
> variable. for example
>
> var0=...
> lb=[0,1,2,3,4];
> ub=...
> .
> .
> .
> i get the results from the optimization
> [..,..,2,..,4]
>
> if you have experienced something like that or you know what goes,
> i
> would appreciate some feedback
>
> Thanks

You gave it bounds on your variables.

Why do you find it strange that some of
those bounds are active? Apparently those
two variables need to be as low as possible
to achieve the minimum objective value.

There is nothing even remotely out of the
ordinary in what you have reported.

HTH,
John D'Errico
From: panos on 4 Jun 2006 18:59
the problem is that this function has been minimized before, using a
simple golden section method. at least i was expecting matlab would
make things easier, but the solution i get with matlab is not even
close. thanks for the reply John!
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