Create a Loop for this process

Question

DARLINGTON ETAJE 2021-6-23

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/863735-create-a-loop-for-this-process

评论： Stephen23 2021-6-24

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

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DARLINGTON ETAJE 2021-6-24

Thank you so much DGM. this is absolutely correct. I am looking for how to accept your answer...

I am grateful.

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?

Stephen23 2021-6-24

"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:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

The neat, simple, very efficient approach is to use indexing, just as DGM has already correctly advised you.

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Answer 1

DGM 2021-6-24

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https://ww2.mathworks.cn/matlabcentral/answers/863735-create-a-loop-for-this-process#answer_732035

在 MATLAB Online 中打开

Generally, using a bunch of numbered variables is something you should try to avoid.

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

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