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Subject: Re: determining the equation of a 3-D surface
Date: Fri, 21 Nov 2008 21:16:03 +0000 (UTC)
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"John D'Errico" <woodchips@rochester.rr.com> wrote in message <gg7777$52l$1@fred.mathworks.com>...
> "loic paccard" <loic.paccard@ecam.fr> wrote in message <gg7679$i6v$1@fred.mathworks.com>...
> > "Johan Carlson" <Johan.E.Carlson@gmail.com> wrote in message <gg73kq$53o$1@fred.mathworks.com>...
> > 
> You actually want to find a minimum point on the
> surface?
> 
> Just use interp2, with one of the smooth interpolants,
> not the default interpolation method which is bilinear.
> Thus, use either 'cubic' or 'spline' as the method.
> 
> Then, use an optimizer, applied to the prediction
> interpolated by interp2. The starting value you would
> use is just the location of the minimum value at any
> of the nodes in the lattice. You might want to apply
> bounds to the optimizer, to keep it within the range
> of the data points, so fmincon is an option, but also
> my fminsearchbnd from the file exchange. You do
> not need anything complicated for the optimization.
> 
> http://www.mathworks.com/matlabcentral/fileexchange/8277
> 
> John

I just to minimize you are right.
Either fmincon or fminsearchbnd would be a way.
Ok but how can I write my objective function fun??
I have only predicted values from real data and interpolations.

x = fminsearch(fun,x0,options)