mlock not working, variables getting cleared in function switch.

M using Multiple function in a single '.m' file.

when i make a function call the previous data of the calling function is getting cleared.

Even if i use mlock then also data is getting cleared from in between function calls.

Is there any other method i can preserve variable and data of my main function.

[Geoff Hayes]

as - how are you storing the previous data? Is this data the output from calling this function before? Can you provide an example that demonstrates this problem?

[as]

function add(a,b)
    mlock
    c= a+b
    d = subtract(a,b)
end

function k = subtract(e,f)
    k = e-f;
end

Thank you Geoff Hayes .In above code when program reaches at ->k=e-f , variable c get destroyed even though i used mlock. If this is not correct use of mlock then please provide an example. What i want is to preserve variable c till the end of execution of function add() and in between call other function too.

In my script i'am loading a ROM.m file with lots of variable in it which i will be using in simulation, but when i call another function workspace is getting cleared.

Answer 1

[Jan]

Create this file:

function demo(In)

persistent v

switch lower(In)
    case 'lock' 
        mlock
        disp('locked')
    case 'unlock'
        munlock
        disp('unlocked')
    case 'set'
        v = rand
    case 'show'
        v
end

end

Now run it:

demo('show')    % v is []
demo('set')
clear('demo')   % v is cleared
demo('show')    % v is []            
demo('set')     % v is set to a value
demo('show')    % v keeps its value
demo('lock')
clear('demo')   % v is not cleared
demo('show')    % v kept its value
demo('unlock')
clear('demo')   % v is cleared
demo('show')    % v is [] again

So usually declaring a variable as persistent is sufficient already and you need mlock only, if a brute program calls clear all (which is a bad programming pattern!).

[as]

Thank you Jan, but here am loading a complete ROM file with lots of variable and their value, so i need to preserve that workspace for my entire run of that function and also call other function in between. Is it possible to load that ROM.m file as persistent?

[Jan]

Of course the workspaces are cleared,when a function is left, except if a variable is stored persistently. So just import the "ROM file" (what ever this means) into a variable, which is declared as persistent.