Problem for creating matrix with loop

A=[1 2 3;4 5 6;7 8 9]

%I wanna create a loop like that

for i=2:3
   A(1:i,:)
end

%What I'm trying to do is getting these matrixes from the loop,

A_1= A(2:2,:)
A_2= A(3:2,:)

For retrieve these matrixes from the loop, what equation I should write in the loop?

Answer 1

[Kelly Kearney]

Your loop and your example aren't the same, since A(3:2,:) is an empty matrix. But I assume you want this:

for ii = 1:10
  B{ii} = A(1:ii,:);
end

This won't work with your example A, which only has 3 rows, but I'm assuming your real A must have 10.

But really, as others have mentioned, it seems a little pointless to create these arrays, since using A(1:ii,:) only adds a few keystrokes over B{ii}, and doesn't involve the unnecessary replication of data.

[sermet]

sorry it should be A(1:i,:)

[sermet]

lastly I'm explaining my situation;

A=[1 2;3 4;5 6] for example

for i=2:3

 A(1:i,:)

end

results;

ans = 1 2 3 4

ans = 1 2 3 4 5 6

How can I spare each of them? I mean when I type ans(2) or ans(1) it should give me the result.

[Kelly Kearney]

ans is a temporary variable that gets used any time that you fail to explicitly assign function output to a variable. I showed you how to assign that data to a variable; if you type B{1} or B{2}, you'll see your results.

Although A(1:2,:) does not equal [1 2 3 4]; it is [1 2; 3 4]. If you want the former, it would be

for ii = 2:3
  B{ii-1} = reshape(A(1:ii,:)', 1, []);
end

Answer 2

[Azzi Abdelmalek]

What is the purpose of creating other variables, when you can access any part of your matrix, whenever you want.

If you want A(2:2,:) , you don't need to create a variable A_1, just write

A(2:2,:)

Or you can create a cell array B

B{1}=A(2:2,:)
B{2}=A(3:2,:)

[sermet]

could you create a loop which determine A(2:2,:) and A(3:2,:)?

[sermet]

then retrieve it from the loop. For example,

for i=2:10
A(1:i,:)
end

A2,A3,....A10 must be created from this loop. What I need is how to retrieve these matrixes from this loop.

[Azzi Abdelmalek]

k=1;
for i=2:10
    k=k+1;
    B{k}=A(1:i,:)
end
B{2}
B{3}