lsqcurvefit is undefined in MathLab version R2007b
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Lieu-Kim Dang
on 16 Jan 2022
Commented: Mathieu NOE
on 17 Jan 2022
Hello MathLab community,
I have copied follwong code from MathWorks example:
xdata = ...
[0.9 1.5 13.8 19.8 24.1 28.2 35.2 60.3 74.6 81.3];
ydata = ...
[455.2 428.6 124.1 67.3 43.2 28.1 13.1 -0.4 -1.3 -1.5];
fun = @(x,xdata)x(1)*exp(x(2)*xdata);
x0 = [100,-1];
x = lsqcurvefit(fun,x0,xdata,ydata)
Running this code gives following error:
??? Undefined function or method 'lsqcurvefit' for input arguments of type 'function_handle'.
Error in ==> Fitt_2 at 11
x = lsqcurvefit(fun,x0,xdata,ydata)
What is the problem in the code?
Can anybody help to solve?
I'm working with MathLab version R2007b.
Thank you.
3 Comments
Matt J
on 16 Jan 2022
Max Heimann
on 16 Jan 2022
Edited: Max Heimann
on 16 Jan 2022
It seems to be part of the optimization toolbox.
https://mathworks.com/help/optim/ug/lsqcurvefit.html
Accepted Answer
Mathieu NOE
on 17 Jan 2022
hello
FYI, you can do basic curve fitting with fminsearch - without the optimization toolbox
clc
clearvars
x = [0.9 1.5 13.8 19.8 24.1 28.2 35.2 60.3 74.6 81.3];
y = [455.2 428.6 124.1 67.3 43.2 28.1 13.1 -0.4 -1.3 -1.5];
f = @(a,b,x) a.*exp(b.*x);
obj_fun = @(params) norm(f(params(1), params(2),x)-y);
sol = fminsearch(obj_fun, [0,0]);
a = sol(1);
b = sol(2);
xfit = linspace(min(x),max(x),100);
yfit = f(a, b, xfit);
figure;
plot(x, y, '+', 'MarkerSize', 10, 'LineWidth', 2)
hold on
plot(xfit, yfit, '-');
TE = sprintf('C = %0.2fe^{%0.3ft}',a, b);
text(x(3), y(3)*1.5, TE);
2 Comments
Rik
on 17 Jan 2022
You do need to be aware that fminsearch is more sensitive to local minima than many other fitters in Matlab, or so I've heard.
Mathieu NOE
on 17 Jan 2022
For those who want to go beyond fminsearch but still lack the optimization toolbox :
More Answers (2)
Lieu-Kim Dang
on 17 Jan 2022
1 Comment
Rik
on 17 Jan 2022
You posted this comment as an answer. Please use the comment section for comments, as the order of answers can change.
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