MATLAB Answers


Undefined function error is very slow to occur

Asked by MathWorks Support Team on 3 Apr 2018
Latest activity Edited by Adam Danz
on 25 Aug 2019 at 17:12
Whenever I type or have a script/m-file with an undefined function or variable (usually through a typo), MATLAB takes about 40 seconds to return the 'Undefined function or variable' message. For example:
>> fg
Undefined function or variable 'fg'.
If I turn off internet access, the delay in producing the message does not occur.

1 Answer

Answer by MathWorks Support Team on 8 Oct 2018
 Accepted Answer

This is most likely due to having network locations on your MATLAB path. While connected to the internet, MATLAB searches through all of these paths before concluding that no such variable/function exists. When not connected to the internet, MATLAB is forced to ignore any network locations. To check this, you can restore the default MATLAB path. Please note that if you have custom paths that you would like to keep on your MATLAB path, you may want to back them up first. See this MATLAB Answers post for more details:
To restore the default MATLAB path, execute the following in the MATLAB Command Window and then restart MATLAB:
>> restoredefaultpath
>> rehash toolboxcache
>> savepath
If this does not correct the issue, then you may have some network locations in your history. You can clear your history by executing the following and then restarting MATLAB.
>> s = settings;
>> s.matlab.desktop.currentfolder.History.PersonalValue = {''}


Thanks, that also addresses the issue I posted on another thread last year. I'll update that thread with a link to this answer.
Since the problem can reoccur, I wrote a function that address disconnected network locations in the Matlab history. The function below creates a GUI that lists all network drives that appear in the Matlab history. The user can select any (or all) of the drives that they no longer have access to and it will remove those from history. The effect was immediate for me and I no longer had to deal with the wait time. Other options in the GUI allow the user to restore the history from a backup if needed. It's a pretty simple.
I'd be interested in knowing if this solves the problem for others, too.
This is among the stupider "features" of matlab that has ever wasted my time. Why are you even searching for things using my history if they are not on my path? And if you are going to do something of such questionable value anyway, how could you implement it in a way that would destroy the user experience because someone switched to a network directory once in order to check something in matlab. For shame! Now at least I'll know when I have foolishly changed to a network directory in matlab and then I get this problem again, I'll remember what to google for to fix it. But really, this is my new job, working around Matlab "features"???

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