How to give an array with dynamic size as a paramter to fucntion?

Hey!

I have a problem. I want to use an array with dynamic size. I mean user can define a size for an array and each element of this array is also an another array:

If user wants an array with a 5 element, the user will wuse the function like that

[A,B,C,D,E]=trying(d)

and each of these A,B,C,D,E will be an array like

A=zeros(d,d,2,d);
B=zeros(d,d,2,d);
C=zeros(d,d,2,d);
D=zeros(d,d,2,d);
E=zeros(d,d,2,d);

or if user wants an array with 2 element, the user can write that:

[A,B]=trying(d)

and the fucntion should do that:

A=zeros(d,d,2,d);
B=zeros(d,d,2,d);

What I mean is that the parameter will be an array with a dynamic size

How can I do that in MATLAB ? I have to use MATLAB and I am very new in MATLAB

Answer 1

[Ameer Hamza]

See varargout(): https://www.mathworks.com/help/releases/R2020a/matlab/ref/varargout.html

Also, read here why using variable names like A, B, C, is not recommended: https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval. Instead use cell arrays.

[Gözde Üstün]

Thanks a lot. I think it is now ok for me.

function [s,varargout] = returnVariableNumOutputs(d,n)
    %A=zeros(d,d,2,d,n);
    nout = max(nargout,1) - 1;
    s = zeros(d,d,2,n);
    for i=1:n
        % s = zeros(d,d,2,n);
        eval(['s' num2str(i) '=zeros(d,d,2,n)']);
    end    
    for k = 1:nout
        varargout{k} = s(k);
    end
end

I know eval is not a good function but for now I have to do that and if you have another idea can you write a small example because in this case eval is the best and I dont know how can I use the cell arrays

[Ameer Hamza]

No need to use eval(). Here is a one-liner

function [varargout] = trying(d)
    varargout = repmat({zeros(d,d,2,d)}, 1, max(nargout,1));
end

[Stephen23]

"I know eval is not a good function ... because in this case eval is the best"

I very much doubt that eval is "the best" for this task.

Ameer Hamza already showed a much better solution using repmat, here are some other much better ways:

function varargout = trying(d)
varargout = cell(1,max(1,nargout));
varargout(:) = {zeros(d,d,2,d)};
end

function varargout = trying(d)
for k = max(1,nargout)):-1:1
    varargout{k} = zeros(d,d,2,d);
end
end

Much simpler, neater, and more efficient using basic MATLAB arrays and indexing.

eval is what beginners use to force themselves into writing slow, complex, inefficient code.

[Gözde Üstün]

thanks a lot