MATLAB: Problem with commdvbs2.slx model in 16a commdemos not on MATLAB search path

MATLABpathrehashsettool

Dear Support,

I don’t know if this is just my setup or a well known problem in R2016a, but many of the shipping examples in R2016a Communications System Toolbox do not run from the doc.

For example, these 3 examples won’t open up. I am sure there are many more examples with this same problem.

Error! Filename not specified.

Undefined function or variable

'commdvbs2'.

The reason appears to be that the path is missing to these files.

These files are in my *C:\MATLAB\R2016a\toolbox\comm\commdemos* directory but this directory is not on my path in 16a. Here is the relevant part of my 16a path:

Error! Filename not specified.

This directory is on my path in 16b and there is no problem opening these models in 16b from the doc. Only 16a is a problem.

Here is the relevant part of my 16b path.

Error! Filename not specified.

Is this just my setup or a widespread problem?

Thank you.

Kerry

Best Answer

I did some further digging, and from my understanding of your workflow, the most likely reason for seeing path deletions in your MATLAB search path could be due to multiple copies of "pathdef.m" on your search path. When you have multiple copies of this file, MATLAB uses the first one found on its path to set all other search paths.

Try to issue the command:

>> which pathdef

And make sure that you only have one entry that is located in matlabroot\toolbox\local\.

As "pathdef.m" is automatically generated, it is entirely possible that somehow another copy of it is created and is located somewhere on your "userpath". As "userpath" takes precedence over all other paths, if there is a corrupted version of "pathdef.m" on that directory, it could be the reason why you are missing those CST demo paths.

I will submit a feature request for consideration of merging search paths in MATLAB in future releases. In the meantime, the only workaround to restore your missing paths while preserving your custom search paths would be the following:

Make sure to delete all extra copies of "pathdef.m", leaving only the one inside matlabroot\toolbox\local\ intact.
Save your current "pathdef.m" as a TXT file somewhere on your drive.
Restore default path on MATLAB and export a copy of the updated "pathdef.m" as TXT file somewhere on your drive
Use an existing DIFF software (such as WinDIFF) to merge two files
Overwrite the existing "pathdef.m" file with the merged version

To open "pathdef.m", you may use the following command in MATLAB command window:

>> edit(which('pathdef'))

Related Solutions

MATLAB: How to move the ‘pathdef.m’ file from its default location to another location in MATLAB 8.1 (R2013a)

The ability to select an arbitrary location for the MATLAB path file 'pathdef.m' is not available in MATLAB 8.1 (R2013a). One possible workaround is detailed below.

By default, the 'pathdef.m' file may be located in either the '$MATLABROOT/toolbox/local' directory or the '$USERPATH' directory, where $MATLABROOT and $USERPATH are the directories displayed after entering the commands

matlabroot

and

userpath

at the MATLAB command line respectively.

The 'pathdef.m' file can be manually copied from either of these directories and placed in an arbitrary directory. To use the copied 'pathdef.m' file at initialization, create a MATLAB file titled 'startup.m' and place it in the '$USERPATH' directory. Copy the lines of code below to the file. If a 'startup.m' file already exists in '$USERPATH', add the lines of code to the end of the file:

% save starting directory
startdir = pwd ;
% specify arbitrary directory containing pathdef.m
pathdir = '<MODIFY>' ;
% change directory so that target 'pathdef.m' has highest precedence
% in the MATLAB search path
cd(pathdir)
% set the MATLAB search path using PATH
path(pathdef)
% change directory back to the starting directory
cd(startdir)

Make sure to modify the string marked "MODIFY" in the above code to the directory to which the 'pathdef.m' file was copied. The 'startup.m' script will be automatically executed upon MATLAB initialization.

MATLAB: Am I getting startup warnings about R2018b folders when launching R2019a using R2019a’s default pathdef

Those folders, such as "\toolbox\matlab\connector2\file", all exist in the MATLAB R2018b installation and are included in the "pathdef.m" that is shipped with MATLAB R2018b. For example, if you pasted "C:\Program Files\MATLAB\R2018b\toolbox\local\matlab\connector2\file" in the Windows File Explorer address bar, you would find that this folder exists on your computer.

Based on the warning messages, it appears that MATLAB is using a different "pathdef.m" file, such as the default 2018b one, instead of the "C:\Program Files\MATLAB\R2019a\toolbox\local\pathdef.m" one that is returned by the "which -all pathdef.m" command. This may happen if your "userpath" is set to an invalid directory, such as the empty char array. To determine if this is the case, execute the following command in the Command Window:

>> userpath

If this command returns an "0×0 empty char array" instead of a folder that exists on your computer, this may be the cause of the issue and may indicate a corrupted preferences migration or install. To resolve this issue, you can do the following:

1) Start MATLAB.

2) Set the "userpath" to be a valid folder that exists on your computer. For example, you could set the "userpath" to be your Documents folder:

>> userpath("C:\Users\username\Documents");

For more information about setting the "userpath", please refer to this documentation page linked below:

https://www.mathworks.com/help/matlab/ref/userpath.html

3) Restart MATLAB. The warning messages will no longer be printed.

4) If this does not resolve the issue, try regenerating your MATLAB preferences or doing a clean reinstall of MATLAB. For instructions on how to do both, please refer to the two links below:

https://www.mathworks.com/matlabcentral/answers/99625-how-do-i-regenerate-my-matlab-preferences

https://www.mathworks.com/matlabcentral/answers/131519-how-do-i-perform-a-clean-installation-of-matlab-on-a-windows-system

Best Answer

Related Solutions

MATLAB: How to move the ‘pathdef.m’ file from its default location to another location in MATLAB 8.1 (R2013a)

MATLAB: Am I getting startup warnings about R2018b folders when launching R2019a using R2019a’s default pathdef

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