How do I use function for a function which has a matrix with variable index?

function[PacksA,PacksB,ContA,ContB,AR,BR,fA,fB]=OutAR_NotOutBR(i,Max,AR,BR,fB,fA,ContB)

if AR<Max

%PacksB, PacksA, ContB, ContA are a vector that varies according to the operation

PacksB=3; fB=fB+1;

PacksA=2; ContA(AR+1)=i; AR=AR+1;

if BR==1

PacksB(ContB(1))=4; fB=fB+1;

ContB(1)=0; BR=BR-1;

elseif BR>=2

PacksB(ContB(1,1:2))=4; fB=fB+2;

if BR==2

ContB=0;

else

ContB(1)=ContB(3); ContB(1,2:3)=0;

end

BR=BR-2;

end

elseif AR==Max

PacksA=3; fA=fA+1;

PacksB=3; fB=fB+1;

if BR>0

PacksB(ContB)=4; fB=fB+BR;

end

ContB=0;

BR=0;

end

%Hello, can you help me solve this error?

%Error in ==> OutAR_NotOutBR at 2

if AR<Max

{??? Output argument "PacksA" (and maybe others)

not assigned during call to

"C:\Users\vignon\Downloads\OutAR_NotOutBR.m>OutAR_NotOutBR".

Answer 1

[James Tursa]

You don't have a branch for the AR>Max case. If you hit that condition, the output variables will not be assigned. Also, ContA doesn't appear to be set in the AR==Max case.

You should check that in all of the possible paths through your code, all of the output variables get assigned to something.

[Fidele Adanvo]

What happens for example if I don't use the ContA in AR==Max but what do I need it in AR>Max ?

[James Tursa]

ContA is an output of your function, so you should set it to something even if your calling function doesn't need it for a particular branch. E.g.,

ContA = [];

If you really want it to be an optional output, you could put it at the end of the list. E.g.,

function[PacksA,PacksB,ContB,AR,BR,fA,fB,ContA]=OutAR_NotOutBR(i,Max,AR,BR,fB,fA,ContB) 

[Fidele Adanvo]

If I set ContA = [ ], does it not modify the value or size of the ContA vector?

[James Tursa]

Yes, of course. That is the point. You are not setting it to anything in one of your branches, so set it to something in that branch. If [] is not appropriate, then set it to something else that is appropriate.

[Fidele Adanvo]

Let's suppose that PackA is a vector of size n. and i = 1: 1: n.

Let's also suppose that every time I call the function I want to define PackA (i) as output arguments. How do I do it?

Arguments in matlab do not have parentheses. Do you have another solution?

[James Tursa]

Not sure exactly what you need to do. But here is the general syntax for having a function alter an element of a vector at the caller:

% Caller code
v = 1:n;  % some arbitrary vector
for k=1:numel(v)
    v(k) = some_function(some_arguments);
end

And you would have separate code for the function

% Function code
function v = some_function(some_arguments)
v = ______; % whatever expression goes into calculating the v element
end

Is that what you are trying to do?

[Fidele Adanvo]

Not entirely true, because I only need to access some elements of the PackA vector and not everything within my function

[Fidele Adanvo]

Por exemple: if i=5

function []=()

PackA(5)=7 it's an example.

As you can see, I don't need to go through all the PacksA elements.