Declaring a global variable in MATLAB

Question

Is there a way to declare global variables in MATLAB?

Please don't respond with:

global x y z; 

Because I can also read the help files.

I've declared a global variable, x, and then done something like this:

function[x] = test()     global x;     test1(); end 

Where the function test1() is defined as:

function test1()     x = 5; end 

When I run test(), my output is x = []. Is there a way I can make it output the x=5, or whatever I define x to be in a separate function? In C, this would be an external variable, and I thought making it a global variable should accomplish just that.

Answer 1

You need to declare x as a global variable in every scope (i.e. function/workspace) that you want it to be shared across. So, you need to write test1 as:

function test1()   global x;   x = 5; end 

Answer 2

Referring to your comment towards gnovice using a global variable can be an approach to solve your issue, but it's not a commonly used.

First of all make sure that your .m files are functions and not scripts. Scripts share a common workspace, making it easy to unwillingly overwrite your variables. In contrast, functions have their own scope.

Use xUnit in order to generate repeatable unit test for your functions. By testing each function involved in your program you will track down the error source. Having your unit test in place, further code modifications, can be easily verified.