How to split a nxn matrix into n vectors

Hi at all, I want to split a nxn matrix in n vectors:

M= [1 2 3 ; 4 5 6 ; 7 8 9];

in

m1 = [1 2 3];

m2 = [4 5 6];

m3 = [7 8 9];

I know that m1=M(1,:);

m2=M(2,:) ... ...

m(n)=M(n,:)

but if the matrix is very large how can I resolve? Thanks a lot

Max

[Yash]

reshape it.

[Max]

How? I try

[X Y]= size(M)

a=reshape(M,X,Y);

but a == M

(I certainly wrong)

Answer 1

[Max]

Ok, thanks at everybody!

Sorry for the wrong word but i not speak English very goog; with struct I mean cell array, sorry ;)

However, how i can have single value in one cell?

Answer 2

[Andrei Bobrov]

m = num2cell(M,2);

your m1 -> m{1}

[Max]

Thanks, but I need separate values in the vector... not "all in one" :D

Answer 3

[Jan]

Using a list of variable like "m1, m2, ..." is a really bad idea and it increases the complexity of programs without any advantage. Andrei's suggestion to use a cell array is much better. See

• Answers: 143
• FAQ: How_can_I_create_variables_A1,A2,...,A10_in_a_loop

[Max]

Thanks a lot for the link.. I've read it... But in my case I need to have separate values in the vector and not in a struct because with separate values I can use polyder functions

[Andrei Bobrov]

eg

M= [1 2 3 ; 4 5 6 ; 7 8 9];
m = num2cell(M,2);
out = polyder(m{1:2}); % for your version out = polyder(m1,m2);

[Jan]

"Struct"? Structs have field names, but I do not see any field names here. Do you mean "cell array"?

I think that Andrei has guessed already, what you are trying to do. But in general in is more efficient, when you explain exactly, what you are trying to do.

Answer 4

[Matt Fig]

Jan is correct. Doing this is a bad idea. If you need to use the POLYDER function on each row of a large array, there are several ways to do it without making many variables.

M = randi(4,6,4);
N = num2cell(M,2);
PD = cellfun(@polyder,N,'Un',0)

Now PD{1} is the POLYDER of M(1,:), PD{2} is the POLYDER of M(2,:), etc.