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# Create matrix...please help me..

Asked by andy ganteng on 2 Nov 2011

I have 2 matrix, A(m,n) and B(o,p). which m=o and n=p, then n and p depend on user input. if input = 3 then n = p =3, if input =10 then n = p =10, and so on. Now, i wanna create matrix C which consist of A and B with the structure like this C=[A(:,1) B(:,1) A(:,2) B(:,2) ...A(:,n) B(:,p)] how can i create that matrix, with n and p depend on user input?iam confuse...please help.

thanks in advance.

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## 2 Answers

Answer by Sven on 2 Nov 2011
Accepted answer
```% So you have 2 matrices that are the same size.
A = rand(4,5)
B = rand(4,5)+50
% Stack them on top of each other
C = cat(1, A, B)
% Rearrange them to have the same 1st dim size as the original
C = reshape(C, size(A,1),[])
```

You see here that the "C" variable has columns like you requested C=[A(:,1) B(:,1) A(:,2) B(:,2) ...A(:,n) B(:,p)]

## 1 Comment

andy ganteng on 2 Nov 2011

thanks, that answer really helpful

Answer by Naz on 2 Nov 2011

I am also confused. Let's say that the user gives you two matrices A and B. It seems like you need to insert columns of one matrix between columns of another (lust like mixing the playing cards). Since both matrices will be the same size we can do the following:

```[m n]=size(A);
C=zeros(m,2*n);
k=1;
for x=2:2:2*n
C(:,x-1)=A(:,k);
C(:,x)=B(:,k);
k+1;
end
```

## 1 Comment

andy ganteng on 2 Nov 2011

thanks, the results is the same as answer above

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