Keep a variable in workspace when calling a function

My question is how to keep a variable in a called function into the workspace.

I was told the code can be written using persistent memory inside the function.

As known, when calling a function, all the variables will be cleared after the function is called, i.e., no variables will appear in workspace.

Can anybody tell me how to work on it.

Thanks in advance.

[Sven]

Yes, there is a thing called a "persistent variable".

Is this what you would like to use?

Answer 1

[Andrej Sternin]

https://de.mathworks.com/help/matlab/matlab_prog/base-and-function-workspaces.html

Answer 2

[the cyclist]

I don't perfectly understand what you mean, but I can think of three possibilities that might help you:

• Send the variable as output
• Use a global variable
• Use the assignin() function

You should easily be able to find information about all of these in the documentation.

Answer 3

[Jonathan]

The code below uses a persistent variable. The first time the function is run, the variable is given the value [] (the empty matrix).

function out = testPersistent()
persistent x

if isempty(x)
  x = 1;
else
  x = x + 1;
end
out = x;
end

When I run the function several times, this is what the output looks like.

>> testPersistent()
ans = 1
>> testPersistent()
ans = 2
>> testPersistent()
ans = 3

I hope this helps.