How to split a matrix into 2 matrixes then join it again?

Question

Isti 2012-5-7

I have a mtrix like this: A =[2,6,3,1,7;9,4,2,6,3;7,1,4,5,3;7,2,5,6,3;4,2,5,3,5]

A =

   6     3     1     7
   4     2     6     3
   1     4     5     3
   2     5     6     3
   2     5     3     5

then i want to split it become 2 matrix A1 and A2. So it will be like this:

A1 =

   6     3     1     7
   4     2     6     3
   1     4     5     3

A2 =

     7     2     5     6     3
     4     2     5     3     5

After i finish with my process with that 2 matrix above, I want join them again into a matrix.

What to do? Thanks before :)

Answer 1

Jan 2012-5-7

A =[2,6,3,1,7;9,4,2,6,3;7,1,4,5,3;7,2,5,6,3;4,2,5,3,5];
A1 = A(1:3, :);
A2 = A(4:5, :);
B = cat(1, A1, A2);  % Or [A1; A2]

These basic array operations are explained exhaustively in the Getting started chapters of the documentation.