fitting equation with condition on 1 parameter
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I have to fit an equation over my data. Equation has two unknows parameters to be found i.e a and b...but if i deliberately want that the b value should lie betweem 0.2 and 2 and then find 'a' and 'b'...how can i do that???
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Matt J
2014년 1월 23일
편집: Matt J
2014년 1월 23일
Here is a simple script for fitting a Gaussian f(z) = a*exp(-b*z^2) using LSQCURVEFIT subject to bounds a>=0, 0<=b<=7. You should run it, study it, and adapt it to your needs.
f=@(p,z) p(1)*exp(-p(2)*z.^2);
x=linspace(0,2,10);
y=f([1,2],x)+rand(size(x))/10; %simulated data
p=lsqcurvefit( f, [.5,.5], x,y, [0,0],[inf,7]); %perform fit
plot(x,y,'*', x, f(p,x)) ;
You should also, of course, read "doc lsqcurvefit" to understand the input syntax and know what additional options you have.
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Amit
2014년 1월 23일
You can use fmincon.
I would think that these a and b are from you previous post, where fminsearch were used. fmincon is similar to fminsearch but support bounds. More details on fmincon is here http://www.mathworks.com/help/optim/ug/fmincon.html
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Alan Weiss
2014년 1월 23일
편집: Alan Weiss
2014년 1월 23일
There are some documentation examples that show how to fit equations. Adding bound constraints is easy for lsqnonlin or lsqcurvefit.
Hope this helps,
Alan Weiss
MATLAB mathematical toolbox documentation
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