In MATLAB, can I have a script and a function definition in the same file?

Question

Suppose I have a function f() and I want to use it in my_file.m, which is a script.

1. Is it possible to have the function defined in my_file.m?
2. If not, suppose I have it defined in f.m. How do I call it in my_file.m?

I read the online documentation, but it wasn't clear what is the best way to do this.

Answer 1

As of release R2016b, you can have local functions in scripts, like so:

data = 1:10;            % A vector of data squaredData = f(data);  % Invoke the local function  function y = f(x)   y = x.^2; end 

Prior to release R2016b, the only type of function that could be defined inside a MATLAB script was an anonymous function. For example:

data = 1:10;            % A vector of data f = @(x) x.^2;          % An anonymous function squaredData = f(data);  % Invoke the anonymous function 

Note that anonymous functions are better suited to simple operations, since they have to be defined in a single expression. For more complicated functions, you will have to define them in their own files, place them somewhere on the MATLAB path to make them accessible to your script, and then call them from your script as you would any other function.

Answer 2

The way I get around this limitation, is to turn my scripts into functions that take no arguments (if I need variables from the global namespace, I either explicitly pass them in the function, or use "evalin" to grab them.)

Then you can define all the additional functions you need in the "script." It's a hack, but I have found it to be quite powerful in those cases where I need several non-trivial functions.

EDIT: Here's a simplistic example. All this can reside in a single file.

function [] = myScriptAsAFunction()    img = randn(200);    img = smooth(img);    figure(1);    imagesc(img);    axis image;    colorbar; end  function simg = smooth(img)     simg = img / 5; end