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Topic: Parameter estimation in Matlab?
Replies: 3   Last Post: Oct 17, 2013 3:45 AM

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Torsten

Posts: 1,439
Registered: 11/8/10
Re: Parameter estimation in Matlab?
Posted: Oct 17, 2013 3:45 AM
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Am Donnerstag, 17. Oktober 2013 01:10:50 UTC+2 schrieb Christiano:
> Em sábado, 12 de outubro de 2013 21h36min38s UTC-3, dpb escreveu:
>

> > On 10/12/2013 11:52 AM, Christiano wrote:
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> >
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> > > Hi,
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> >
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> > >
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> > > I have the following formula representing a physical system:
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> >
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> > > a = K1*arctg[K2*(w1-K3*w2)/(w1+K3*w2)]
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> >
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> > > Known constants ===> w2
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> >
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> > > Unknown constants ===> K1, K2, K3
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> >
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> > >
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> > > That is, "w1" input generate "a" output.
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> > > Through experimentation I have a table ("w1","a").
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> >
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> > >
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> > > Is there any command in matlab to find the parameters K1, K2, K3
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> >
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> > > using this table ("w1","a") ??
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> >
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> > Whassup w/ this thing of everybody calling data arrays and vectors
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> >
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> > "tables"????
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> > What's arctg? arctan() maybe???
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> > doc lsqnonlin
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> >
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> >
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> >
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> > --
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>
>
> dpb, thanks for your notes, I started with matlab less than 1 week.
>
> I'll be honest, I do not understand nothing of matlab. I'm trying to use lsqnonlin but is a bit difficult.
>
> What is the basis that I need to understand the docs matlab?
>
> Can recommend books?
>
> I need it to do my graduation project because it will be necessary to do laboratory experiments of a physical system.


x0 = [1; 1; 1] % Starting guess
[x,resnorm] = lsqcurvefit(@myfun,x0,w1,a);

function F = myfun(x,w1)
K1=x(1);
K2=x(2);
K3=x(3);
w2=...;
F = K1*atan(K2*(w1-K3*w2)./(w1+K3*w2));

Best wishes
Torsten.



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