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2016b fitlm giving me error "Undefined function or variable 'istall'."

Latest activity Answered by Abhinav Gaur on 26 Jul 2017

I recently upgraded to MatLab 2016b, and a script that worked fine in 2016a is now giving me issues. In particular, fitlm(x,y) is giving me the error "Undefined function or variable 'istall'." Thanks in advance.

x = [1 2 3 4 5 6 7 8 9 10];
y = [1 4 9 16 25 36 48 64 91 99];
test = fitlm(x,y);
Undefined function or variable 'istall'.
Error in classreg.regr.TermsRegression.createFormula (line 621)
                isTall      = istall(X);
Error in LinearModel.createFormula (line 1367)
            formula = classreg.regr.TermsRegression.createFormula(supplied,modelDef, ...
Error in (line 1203)
            model.Formula = LinearModel.createFormula(supplied,modelDef,X, ...
Error in fitlm (line 117)
model =,varargin{:});


Can you post the results of

which -all istall
which -all fitlm

I have the same problem (istall not found).

>> ver('matlab')
MATLAB Version: (R2016b)
MATLAB License Number: ••••••
Operating System: Microsoft Windows 7 Professional  Version 6.1 (Build 7601: Service Pack 1)
Java Version: Java 1.7.0_60-b19 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode
MATLAB                                                Version 9.1         (R2016b)
>> which -all istall
'istall' not found.
>> which -all fitlm
C:\Program Files\MATLAB\R2016b\toolbox\stats\classreg\fitlm.m

Edit: Very dirty workaround (works if you're not working with tall arrays): Add this function to your path:

function out = istall(varargin)
out = false;

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2 Answers

Answer by michio
on 17 Oct 2016
Edited by michio
on 20 Oct 2016

Hmm I could not reproduce your issues. One possibility is that the error comes due to corrupt path or installation. Have you tried restore your path settings? If no, it's worth a try.

If it allows please follow the steps below to restore search path to its factory-installed state.

1. Execute the commands:

 rehash toolboxcache

2. Execute your code:

x = [1 2 3 4 5 6 7 8 9 10];
y = [1 4 9 16 25 36 48 64 91 99];
test = fitlm(x,y); 

If this works fine, then execute the following command to save the path


  1 Comment

istall is a MATLAB function introduced in R2016b.

If you installed successfully and the path is correct, it should be located in


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Answer by Abhinav Gaur on 26 Jul 2017

In my case, as @Kojiro suggested, the file


did exist in the directory


I added it manually using 'addpath()' and now fitglm works for me.


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