deleting a huge matrix after passing its local copy to a function in Matlab

Question

Considering we have a huge matrix called A and we pass it to the function func(A) wherein func I do a set of computations like:

func(A):

B=A;

%% a lot of processes will happen on B here 

return B;

end

The fact is that as soon as I pass A to B I would not have anything to do with A anymore in my Matlab session so it takes an unnecessary space in memory. Is it possible to remove its instance in the scope of the script that called func?

Answer 1

Using evalin with the option caller you can evaluate expression clear A:

function A = func(A)
    evalin('caller', 'clear A')
    A(1) = 5;
end

However we usually don't know the name of the input variable so we can use inputname to get the actual name of the workspace variable:

function A = func(A)
    name = inputname(1);
    if ~isempty(name)
        evalin('caller', ['clear ' name])
    end
    A(1)=4;
end

1.Here inputname(1) means the actual name of the first argument.

2.Work directly with A because if you copy A into B the function scope will have two copies of A.