How to create an array of matrices?

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Goncalo Costa
Goncalo Costa 2022-1-23
回答： Thomas 2023-6-22
If I have 3 matrices:
A = [1 2 ; 3 4]
B = [5 6 ; 7 8]
C = [9 10 ; 11 12]
And I want to create a greater matrix with these inside like D = [A ; B ; C], that would result in something like:
D = [1 2 ; 5 6 ; 9 10
3 4 ; 7 8 ; 11 12 ]
I have tried writing something as simple as
D = [A , B , C]
But this solely puts all these matrices side by side into a single matrix, whilst I intend to keep them all separately in an array, to create a "row" of matrices...

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回答（3 个）

the cyclist
the cyclist 2022-1-23
编辑：the cyclist 2022-1-23
Ran in:
You could use a cell array:
A = [1 2 ; 3 4];
B = [5 6 ; 7 8];
C = [9 10 ; 11 12];
D = {A, B, C}
D = 1×3 cell array
{2×2 double} {2×2 double} {2×2 double}
I think the best answer will depend on what you are planning on doing with the result afterward.
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Goncalo Costa
Goncalo Costa 2022-1-23
I am trying to go through each matrix in a for loop. But when I tried writing it that way, I thought that the answer you showed below meant it hadn't worked, and that therefore I couldn't use this for a for loop.
Thank you so much for your help.

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the cyclist
the cyclist 2022-1-23
Ran in:
Given your comment on my other answer, another possible solution is to stack the matrices as slices in a 3rd dimension:
A = [1 2 ; 3 4];
B = [5 6 ; 7 8];
C = [9 10 ; 11 12];
D = cat(3,A,B,C);
for ii = 1:3
D(:,:,ii)
end
ans = 2×2
1 2 3 4
ans = 2×2
5 6 7 8
ans = 2×2
9 10 11 12
Thomas
Thomas 2023-6-22
function aM = arrayofmatrices(A,B,C)
aM(:,:,1) = A;
aM(:,:,2) = B;
aM(:,:,3) = C;
end
This only works when A, B and C have the same sidelenths. If not you need a cell array.

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