# lsqcurvefit is undefined in MathLab version R2007b

6 views (last 30 days)
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.
Max Heimann on 16 Jan 2022
It seems to be part of the optimization toolbox.
https://mathworks.com/help/optim/ug/lsqcurvefit.html

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 CommentsShowHide 1 older comment
Mathieu NOE on 17 Jan 2022
For those who want to go beyond fminsearch but still lack the optimization toolbox :

Lieu-Kim Dang on 17 Jan 2022
Hello Mathieu,
many thanks for your valuable solution. I will try it out.
Mathieu NOE on 17 Jan 2022
my pleasure !

Lieu-Kim Dang on 17 Jan 2022
Hello Max,
thank you for your information. I'm contacting MAthLab to get the license for this toolbox.
Rik on 17 Jan 2022