MATLAB: How to intialize a variable only once?the below written code should execute only once.later the value must b retained. how it is done

MATLABvariable

example
    persistent a
    if isempty (a)
    a=0;
    end

Best Answer

You say "the value assigned to 'a' in the previous computation should be retained, after I close the m-file and run it next time." So, save it to a .mat file on disk with save() then. Recall it with load() the next time you run the program.
persistent a
if isempty (a)
   a=0;
   if exist('a.mat', 'file')
       % Recall a from mat file
       s = load('a.mat');
       a = s.a;
   end
end
% more code....
% Then just before you exit this routine, save it out to the disk file
% for recall by later runs of this program.
save('a.mat', a);
Of course since you're saving it and recalling it across different runs, it no longer needs to be persistent. You could just do load() and save() and not have it be persistent.
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