Error: Unable to use a value of type 'fittype' as an index.

Hi there,

I am struggling to understand how to solve an error occurring when using a customized non-linear fit function with Matlab.

Here is the function I need to employ:

CAO = 0.02;
expFIT = fittype(@(a, b, CD) a*((CA0+CD+b)-sqrt((CA0+CD+b).^2-4*CA0*CD)) ,'independent',{'CD'});

Up to here, no error.

Then, when it comes to perform the actual fit I get the following statement: '

Unable to use a value of type 'fittype' as an index'. 

And it goes to the line with the fit command:

FIT = fit(CD, Abs, expFIT,'Robust','on');

Thank you in advance for any feedback!

Answer 1

[Steven Lord]

Rename the variable you created with the name fit.

[Claudia Dessi]

Hi there,

I did rename the variable as AbsFIT (instead of FIT) but the error persists.

My issue is that I do not understand the type of error this time.

[Steven Lord]

Did you clear the variable named fit after you executed the command AbsFIT = fit; (or whatever similar command you used?)

[Claudia Dessi]

No, I did not.

I did it this morning and now it works. It is curious though that FIT name for another fit command in another code was just fine, and I thought that capital letters may not create confusion to the program.

thanks!

Answer 2

[Prinkle Sharma]

While compiling:

[~,score_knn] = resubPredict(KNNModel);
labels = predict(KNNModel,test(:,1:9));

I'm experiencing similar error: "Unable to use a value of type 'ClassificationKNN' as an index." with the line below

[Xknn, Yknn, Tknn, AUCknn] = perfcurve(labels,score_knn(:,KNNModel),'true');

Can someone help me with this please ?