Global Variables in Octave

In this lesson, I will explain how to use global variables in Octave.

So, what is a global variable? A global variable can be read from any part of the program, even within the functions of the program, without being passed as a parameter.

Let me give you a practical example.

To define a global variable, you use the global statement.

>> global a=1

Octave creates a new variable 'a' and assigns it the value of 1.

>> a
a = 1

To access the global variable 'a' within a function without passing it as a parameter, include the statement 'global a' within the function.

>> function f()
global a
a
endfunction

The function accesses the global variable even if it's not passed as a parameter.

>> f
a = 1

The function 'f()' can access the value of the global variable 'a', but cannot modify it.

How to check if a variable is global

To check if a variable is global, you can use the following function:

>> isglobal('a')

This function returns a value of 1 if the variable is global, and 0 if it is not global.

How to modify the value of a global variable

Once a variable has been initialized, you cannot initialize it again.

>> global a=1
>> global a=2
>> a
a = 1

If you want to assign a new value to it, you can do so in this way:

>> a=2

You can also modify the value of the global variable inside a function.

The new value of the global variable is accessible from any other part of the program.

How to delete a global variable

To delete a global variable, you can use the "clear" command.

>> clear('a')

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