Could anyone can help me with a question about function workspace?

I came to a question with following code:

Function [x,y] = myworkspace(a,b)
x = a + b;
y = x * b;
z = a + b;
end

Example Q1: What will the value of a,b,x,y and z be after the following code is run?

Example A1 is as follows:

>>clear all
>>a = 2;
>>b = 3;
>>z = 1;
>>[y,x] = myworkspace(b,a)
y = 5
x = 10
*>>z
z = 1*

Example Q2: What will the value of a,b,x,y and z be after the following code is run?

Example A2 is as follows as well:

>>x = 5;
>>y = 3;
>>[b,a] = myworkspace(x,y)
b = 8
a = 24
*>>z
??? Undefined function or variable 'z'.*

I am wondering why the values of z above are like that (in Bold)? I am confusing since z = a + b and both elements are defined...

Could you please tell me why it is the case?

[Henry Mao]

Sorry for my mistyping, it's not in bold but between asterisks...

Answer 1

[dpb]

The definitions in the function are local and the dummy arguments are assigned values by position, NOT by association of name with that of the calling workspace variable--they don't have to agree whatsoever--you can call myworkspace(z,pi) just as well and internally to the function you'd have (first case) a=1,b=3.141...

Also arguments are passed but cannot be modified; they're essentially passed by value albeit that may not be the actual passing mechanism it's what it appears to be.

Hence, in the first case the value of z is that previously defined; in the second z hasn't been defined as whatever it is internal to the function workspace is temporary and exists only in that scope; when the function returns, whatever it was therein is lost irretrievably since you only return the result of x and y.

[Henry Mao]

Thank you so much for your patience and clear answer! I finally got it! Thank you again!