Use variables from workspace from previous run

Hello guys,

is the following method possible to implement in Matlab:

If I run my function, it will load some mat files into the workspace. They are quite big and need over a secound for loading. As for this program, every second is really important, I am asking myself, if it is possible to load the mat files only at the first run after opening Matlab and after that just use them from the workspace?

I tried to not use clear and to check if the variable already exists with the exist function. Unfortunatly, this method doesn't work.

Do you have any suggestions?

Thank you very much in advance.

Answer 1

[Walter Roberson]

Use

persistent VariableName

The value will be initialized to [] so isempty() tells you whether you need to load the value

Answer 2

[Dimitris Kalogiros]

There are two possible scenarios:

• your matlab code overwrites some of the preloaded values
• you "load" the files inside the function call, so everything disappears when the function finishes its job

Provided that you don't use any "clear" command, you can use an m-file in order to load these useful files and store data containing to them at a variable (or variables) with a specific name. Then at the same m-file you can call your function and pass the data as prameters (maybe you have to change the definition of your function).

...at the end of the day, just run this m-script

[Gerrit]

Yes, the data loads inside the function. But this is a must, because I need a function to call from C++

[Dimitris Kalogiros]

So, the solution I've already proposed, has to fit to your problem.

This is what I meant at my answer

clear; 
clc;


% call C++ function
myData=getMyData;

N=100;
for k=1:N
    
    % keep your data protected
    myDataCopy=myData;
    
    %matlab function that processes my data
    matlabFunctionThatProcessesMyData(Parameter1, Parameter2, myDataCopy);
    
end

[Gerrit]

Thank you, but I need to call the Matlab function from C++. Not a C++ Function in Matlab.