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

2020 11 17
1 个回答
更新时间：2020 11 17
3 次查看（30 天）

0 个投票

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".

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回答（1 个）

James Tursa
James Tursa 2020-11-17
编辑：James Tursa 2020-11-17

0 个投票

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.

8 个评论
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Fidele Adanvo
Fidele Adanvo 2020-11-17
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
James Tursa 2020-11-17
编辑：James Tursa 2020-11-17
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
Fidele Adanvo 2020-11-17
If I set ContA = [ ], does it not modify the value or size of the ContA vector?
James Tursa
James Tursa 2020-11-17
编辑：James Tursa 2020-11-17
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
Fidele Adanvo 2020-11-17
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
James Tursa 2020-11-17
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
Fidele Adanvo 2020-11-17
Not entirely true, because I only need to access some elements of the PackA vector and not everything within my function
Fidele Adanvo
Fidele Adanvo 2020-11-17
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.

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