[matlab] Is it possible to define more than one function per file in MATLAB, and access them from outside that file?

When I was studying for my undergraduate degree in EE, MATLAB required each function to be defined in its own file, even if it was a one-liner.

I'm studying for a graduate degree now, and I have to write a project in MATLAB. Is this still a requirement for newer versions of MATLAB?

If it is possible to put more than one function in a file, are there any restrictions to this? For instance, can all the functions in the file be accessed from outside the file, or only the function that has the same name as the file?

Note: I am using MATLAB release R2007b.

I define multiple functions in one .m file with Octave and then use the command from within the .m file where I need to make use of the functions from that file:

source("mycode.m");

Not sure if this is available with Matlab.

octave:8> help source
'source' is a built-in function

 -- Built-in Function:  source (FILE)
     Parse and execute the contents of FILE.  This is equivalent to
     executing commands from a script file, but without requiring the
     file to be named `FILE.m'.

I really like SCFrench's answer - I would like to point out that it can easily be modified to import the functions directly to the workspace using the assignin function. (Doing it like this reminds me a lot of Python's "import x from y" way of doing things)

function message = makefuns
  assignin('base','fun1',@fun1);
  assignin('base','fun2',@fun2);
  message='Done importing functions to workspace';
end

function y=fun1(x)
  y=x;
end

function z=fun2
  z=1;
end

And then used thusly:

>> makefuns
ans =
Done importing functions to workspace

>> fun1(123)
ans =
   123

>> fun2()
ans =
     1

Generally, the answer to your question is no, you cannot define more than one externally visible function per file. You can return function handles to local functions, though, and a convenient way to do so is to make them fields of a struct. Here is an example:

function funs = makefuns
  funs.fun1=@fun1;
  funs.fun2=@fun2;
end

function y=fun1(x)
  y=x;
end

function z=fun2
  z=1;
end

And here is how it could be used:

>> myfuns = makefuns;
>> myfuns.fun1(5)    
ans =
     5
>> myfuns.fun2()     
ans =
     1

I have try with the SCFRench and with the Ru Hasha on octave.

And finally it works: but I have done some modification

function message = makefuns
    assignin('base','fun1', @fun1);   % Ru Hasha
    assignin('base', 'fun2', @fun2);  % Ru Hasha
    message.fun1=@fun1;               % SCFrench
    message.fun2=@fun2;               % SCFrench
end

function y=fun1(x)
    y=x;
end

function z=fun2
    z=1;
end

Can be called in other 'm' file:

printf("%d\n", makefuns.fun1(123));
printf("%d\n", makefuns.fun2());

update:

I added an answer because neither the +72 nor the +20 worked in octave for me. The one I wrote works perfectly (and I tested it last Friday when I later wrote the post).

Along the same lines as SCFrench's answer, but with a more C# style spin..

I would (and often do) make a class containing multiple static methods. For example:

classdef Statistics

    methods(Static)
        function val = MyMean(data)
            val = mean(data);
        end

        function val = MyStd(data)
            val = std(data);
        end
    end

end

As the methods are static you don't need to instansiate the class. You call the functions as follows:

data = 1:10;

mean = Statistics.MyMean(data);
std = Statistics.MyStd(data);     

You could also group functions in one main file together with the main function looking like this:

function [varargout] = main( subfun, varargin )
[varargout{1:nargout}] = feval( subfun, varargin{:} ); 

% paste your subfunctions below ....
function str=subfun1
str='hello'

Then calling subfun1 would look like this: str=main('subfun1')

As of R2017b, this is not officially possible. The relevant documentation states that:

Program files can contain multiple functions. If the file contains only function definitions, the first function is the main function, and is the function that MATLAB associates with the file name. Functions that follow the main function or script code are called local functions. Local functions are only available within the file.

However, workarounds suggested in other answers can achieve something similar.

The only way to have multiple, separately accessible functions in a single file is to define STATIC METHODS using object-oriented programming. You'd access the function as myClass.static1(), myClass.static2() etc.

OOP functionality is only officially supported since R2008a, so unless you want to use the old, undocumented OOP syntax, the answer for you is no, as explained by @gnovice.

EDIT

One more way to define multiple functions inside a file that are accessible from the outside is to create a function that returns multiple function handles. In other words, you'd call your defining function as [fun1,fun2,fun3]=defineMyFunctions, after which you could use out1=fun1(inputs) etc.