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Create a Loop for this process

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DARLINGTON ETAJE
DARLINGTON ETAJE on 23 Jun 2021
Commented: Stephen on 24 Jun 2021
I have a process which works fine. You can see the code below. I need to create a loop for the process. I need the loop to take in multiple number of c. c is usually a 3 by 3 matrix. L is usual a 1 by 12 matrix.
n=3;
c1=[12 40 13;10 11 70;80 9 1]; % C matrix for member 1
c2=[0 0 -1;0 1 0;1 0 0]; % C matrix for member 2
c3=[0 1 0;0 0 1;1 0 0]; % C matrix for member 3
L1=[13 14 15 16 17 18 1 2 3 4 5 6]; % for member 1
L2=[1 2 3 4 5 6 7 8 9 10 11 12]; % for member 2
L3=[19 20 21 22 23 24 7 8 9 10 11 12]; % for member 3
L=[L1;L2;L3];
T1=zeros(size(L1,1));
T2=zeros(size(L2,1));
T3=zeros(size(L3,1));
for i=1:n
for j=1:n
T1(i,j)=c1(i,j);
T1(i+3,j+3)=c1(i,j);
T1(i+6,j+6)=c1(i,j);
T1(i+9,j+9)=c1(i,j);
T2(i,j)=c2(i,j);
T2(i+3,j+3)=c2(i,j);
T2(i+6,j+6)=c2(i,j);
T2(i+9,j+9)=c2(i,j);
T3(i,j)=c3(i,j);
T3(i+3,j+3)=c3(i,j);
T3(i+6,j+6)=c3(i,j);
T3(i+9,j+9)=c3(i,j);
end
end
  5 Comments
Stephen
Stephen on 24 Jun 2021
"The only thing left is to find a way to create variabe names to assign each 12 by 12 matrices so I dont have 3D variables....is that even possible?"
Of course it is possible, if you want to force yourself into writing slow, complex, inefficient code that is difficult to debug:
The neat, simple, very efficient approach is to use indexing, just as DGM has already correctly advised you.

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Answers (1)

DGM
DGM on 24 Jun 2021
Generally, using a bunch of numbered variables is something you should try to avoid.
That said, you can make the above code into a function that will return a variable length list of T arrays for an equal-length list of C arrays.
C1 = rand(3,3);
C2 = rand(3,3);
dn = 4;
% output list length should be same as number of Cn arrays
[T1 T2] = makebdiag(dn,C1,C2)
function varargout = makebdiag(dn,varargin)
varargout = cell(size(varargin));
for n = 1:numel(varargin)
arglist = repmat(varargin(n),[1 dn]);
varargout{n} = blkdiag(arglist{:});
end
end

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