Thread Subject:

create matrix of vectors

Hi, i have two matrices:

a =

1 2 3
4 5 6
7 8 9

b =

9 8 7
6 5 4
3 2 1

i want to create a matrix of vectors using the logic

element1 = [a(1,1) b(1,1) 0]

and so on.... in fact i would like to extend the problem to two nxn matrices while appending the z dimension. How would I go about populating such a matrix?

"arron lacey" <arronslacey@gmail.com> wrote in message <js17et$ku9$1@newscl01ah.mathworks.com>...
> Hi, i have two matrices:
>
> a =
>
> 1 2 3
> 4 5 6
> 7 8 9
>
> b =
>
> 9 8 7
> 6 5 4
> 3 2 1
>
> i want to create a matrix of vectors using the logic
>
> element1 = [a(1,1) b(1,1) 0]
>
> and so on.... in fact i would like to extend the problem to two nxn matrices while appending the z dimension. How would I go about populating such a matrix?

When you say a "matrix of vectors", I assume you mean a cell array. If so, then do as below. Otherwise, it's not clear what you mean. The elements of a "matrix" are scalars by definition.

C=num2cell([a(:),b(:),zeros(size(b(:)))],2);
C=reshape(C,size(b));

On 6/22/2012 2:39 AM, arron lacey wrote:
> Hi, i have two matrices:
>
> a =
>
> 1 2 3
> 4 5 6
> 7 8 9
>
> b =
>
> 9 8 7
> 6 5 4
> 3 2 1
>
> i want to create a matrix of vectors using the logic
>
> element1 = [a(1,1) b(1,1) 0]
>
> and so on.... in fact i would like to extend the problem to two nxn matrices while appending the z dimension. How would I go about populating such a matrix?
>

hard to understand. may be this is what you want. Try to write
a more complete output example.

EDU>> N=3
a = [1 2 3;
      4 5 6;
      7 8 9];

b = [9 8 7;
      6 5 4;
      3 2 1]

C=[a(:) b(:) zeros(N^2,1)]

C =
      1 9 0
      4 6 0
      7 3 0
      2 8 0
      5 5 0
      8 2 0
      3 7 0
      6 4 0
      9 1 0


--Nasser

"Nasser M. Abbasi" <nma@12000.org> wrote in message <js192b$1qh$1@speranza.aioe.org>...
> On 6/22/2012 2:39 AM, arron lacey wrote:
> > Hi, i have two matrices:
> >
> > a =
> >
> > 1 2 3
> > 4 5 6
> > 7 8 9
> >
> > b =
> >
> > 9 8 7
> > 6 5 4
> > 3 2 1
> >
> > i want to create a matrix of vectors using the logic
> >
> > element1 = [a(1,1) b(1,1) 0]
> >
> > and so on.... in fact i would like to extend the problem to two nxn matrices while appending the z dimension. How would I go about populating such a matrix?
> >
>
> hard to understand. may be this is what you want. Try to write
> a more complete output example.
>
> EDU>> N=3
> a = [1 2 3;
> 4 5 6;
> 7 8 9];
>
> b = [9 8 7;
> 6 5 4;
> 3 2 1]
>
> C=[a(:) b(:) zeros(N^2,1)]
>
> C =
> 1 9 0
> 4 6 0
> 7 3 0
> 2 8 0
> 5 5 0
> 8 2 0
> 3 7 0
> 6 4 0
> 9 1 0
>
>
> --Nasser

Thanks very much for the reply. It is interesting to here that the element of a matrix can only be a scalar. Ideally what I want is to be able to read in two arrays of any size (although both the same size) and then create a matrix, or cell array which holds something like:

cellarray =

[a(1,1) b(1,1) 0] [a(1,2) b(1,2) 0] [a(1,3) b(1,3) 0] ........... [a(1,n) b(1,n) 0]
[a(2,1) b(2,1) 0] [a(2,2) b(2,2) 0] [a(2,3) b(2,3) 0]
[a(3,1) b(3,1) 0] [a(3,2) b(3,2) 0] [a(3,3) b(3,3) 0]
.
.
.
[a(n,1) b(n,1) 0]


does that make it a bit clearer? that means that i can use each element in a cross product with another cell array constructed in a similar way.

also if I do:

C=[a(:) b(:) zeros(N^2,1)]

i get

size(C(1,1)) =

1 1

but i actually need the size of each element to be 1 3 so i can use it in a cross product.

i.e. if i do:

C = [A(1,1) B(1,1)]

I get size(C) = 1 3

so the dimensions are correct.

"arron lacey" <arronslacey@gmail.com> wrote in message <js1h47$rp6$1@newscl01ah.mathworks.com>...
>
> cellarray =
>
> [a(1,1) b(1,1) 0] [a(1,2) b(1,2) 0] [a(1,3) b(1,3) 0] ........... [a(1,n) b(1,n) 0]
> [a(2,1) b(2,1) 0] [a(2,2) b(2,2) 0] [a(2,3) b(2,3) 0]
> [a(3,1) b(3,1) 0] [a(3,2) b(3,2) 0] [a(3,3) b(3,3) 0]
> .
> .
> .
> [a(n,1) b(n,1) 0]
>
>
> does that make it a bit clearer? that means that i can use each element in a cross product with another cell array constructed in a similar way.
==================

That does make it clearer, but it's what I already gave you in my previous post.

>
> That does make it clearer, but it's what I already gave you in my previous post.

HI Matt yes - sorry, I was replying to the last reply which was Nasser's, was going to reply to yours but got called into a meeting. Yes the way you have done it is exactly what I am looking for. thanks very much.

"arron lacey" <arronslacey@gmail.com> wrote in message
news:js1ifb$3rq$1@newscl01ah.mathworks.com...
> also if I do:
>
> C=[a(:) b(:) zeros(N^2,1)]
>
> i get
> size(C(1,1)) =
>
> 1 1
>
> but i actually need the size of each element to be 1 3 so i can use it in
> a cross product.

Take a look at C(1, :). That extracts one whole row of C, and by the way C's
been constructed that row is 1-by-3.

--
Steve Lord
slord@mathworks.com
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