fit function in Matlab 2020

I'm trying to use the fit function (see example below), but keep getting this error "Check for missing argument or incorrect argument data type in call to function 'fit' "

% Code:
load census;
f=fit(cdate,pop,'poly')

%

I get the error even using this simple example, which is the same one that appears here Fit Help Doc

Thanks in advance for the help. I'm not sure how to fix this.

Answer 1

[Elizabeth Huaroc]

I had the same problem and after reviewing the following link, I realised that I didn't install the curve fitting toolbox when I updated my version of Matlab.Therefore, Matlab called "fit" from the stats toolbox function which has different input types. More details in the aswer of @Bernard Beitz in the link below. I changed from Matlab 2020a to 2020b and had to run the installer again for installing the missing toolboxes.

https://ch.mathworks.com/matlabcentral/answers/589969-check-for-missing-argument-or-incorrect-argument-data-type-in-call-to-function-fit-using-two-1x1#answer_503008

Answer 2

[Navya Seelam]

poly is not a valid input argument for the fit function. Try using poly1 or poly2 for linear and quadratic fit respectively. For more valid fit types go through this link.

[JP]

Hi Navya,

I have the same problem, also when using poly1 or poly2:

load census;

f=fit(cdate,pop,'poly1');

plot(f,cdate,pop)

I use Matlab 2020a.

Do you know what's the problem?

Best

[Steven Lord]

Do you have Curve Fitting Toolbox installed?

[Zhixue]

Same here, fit function not working. Has MABLAB changed anything?

[spencer Jordan]

Did anyone here solve this issue? I just updated to 2020a and now all the scripts I have that use 'fit' no longer work.

[Jan Skerswetat]

same error here with 2020b. My code works with 2019b version, but not with the 2020b. Using fit and 'gauss1'.