Instructions on how to add a directory to your search path

Last updated 2020-07-20 by Adam Lu

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In MATLAB, to be able to call a custom script/function, one of the following must be true:

1. It exists in the current directory.
2. The directory containing it exists in the search path for your MATLAB session.

There are two main methods one can add a directory to the search path.

Method 1: Add it to the search path for whenever your code is called (Recommended)

• In your code, apply the addpath command:

    addpath('/home/Matlab/Adams_Functions')
    addpath('/home/Matlab/Downloaded_Functions/ViolinPlot')
  

• If /home/Matlab/Adams_Functions is within your search path by default, you could add the following code block from function_template.m:

    % Add path for custom functions only if not compiled
    if ~isdeployed
        % Locate the functions directory
        functionsDirectory = locate_functionsdir;
      
        % Add path for custom functions
        addpath_custom(fullfile(functionsDirectory, 'Adams_Functions'));
        addpath_custom(fullfile(functionsDirectory, 'Downloaded_Functions'));
    end
  

• Alternatively, you could add the following code block

    % Add path for custom functions only if not compiled
    if ~isdeployed
        if exist(fullfile(pwd, 'Adams_Functions'), 'dir') == 7
            functionsdirectory = pwd;
    elseif exist('/home/Matlab/', 'dir') == 7
            functionsDirectory = '/home/Matlab/';
    elseif exist('/scratch/al4ng/Matlab/', 'dir') == 7
            functionsDirectory = '/scratch/al4ng/Matlab/';
        else
            error('Valid functionsDirectory does not exist!');
        end
      
        addpath(fullfile(functionsDirectory, 'Adams_Functions'));
    end
  

• Explanation:

  • If the code is to be compiled in the future, addpath() would not work when compiled. One can check whether the code was compiled with isdeployed
  • If you want the code to work across servers, including Rivanna, you can check for existence of the shared Matlab folder.
  • addpath_custom.m (available in /home/Matlab/Adams_Functions) is superior over addpath() because it will not add a path if it already exists. This would prevent the search path from becoming too long when a function is repeatedly called.

Method 2: Add it to the search path for all future MATLAB sessions called from your home directory

• Click on Set Path and interactively add the directory containing the script/function.

  Note: If you use the Set Path interface, the option Add With Subfolders is NOT recommended unless you are absolutely sure the contents of the subfolders do not interfere with the built-in functions or the more updated versions of your functions.

• The search path can be saved as a file pathdef.m in your home directory. If so, the next time you open MATLAB from a terminal (which defaults to your home directory), the saved search path will be restored.
  • pathdef.m can be saved in any directory, but one must start the matlab command from that directory to load the file.
  • If you start MATLAB from a directory without pathdef.m, only the default paths will be loaded.

• If MATLAB has been upgraded, earlier versions of pathdef.m may cause errors when called. In this case, remove the file with the command:

    # In a terminal
    rm ~/pathdef.m