How do I create a 2D sparse matrix?

Hallo, When I want to creat a sparse matrix, and and according to the i verctor( index) the element must be equal =1

say i=[6 12 18 24 19 13 7 1]; A=sparse(i,i,ones(1,8)); then I have A =

   (1,1)        1
   (6,6)        1
   (7,7)        1
  (12,12)       1
  (13,13)       1
  (18,18)       1
  (19,19)       1
  (24,24)       1

Now:I want to creat a A 2D sparse matrix with vector i, but with every element are a 2D matrix 3x3 for exmaple A(1,1) is 2D matrix of dimension 3x3=[1 0 0;0 1 0; 0 0 1]; thank you in advance

[Bruno Luong]

A (sparse) matrix can contain numerical elements and nothing else. What exactly you want to do?

Answer 1

[Marwa Helemish]

sorry Andrew,i canot accept it because , it is not want I mean. Many thanks again

[Andrew Newell]

Then what do you mean? I suggest editing your original question to clarify it.

Answer 2

[Andrew Newell]

Here is how you would do it for your example:

N = 6; % I assume this is a square matrix?
A = zeros(3,3,N^2);
A3 = eye(3);

indexList = [6 12 18 24 19 13 7 1];
for i=indexList
    A(:,:,i) = A3;
end

A = num2cell(A,[1 2]);
A = reshape(A,N,N);
A = sparse(cell2mat(A));

EDIT: If you're really after a sparse cell array of matrices, try looking at Sparse cell arrays.

[Todd Flanagan]

Marwa says, "thanks alot"

[Todd Flanagan]

Andrew says, "If you like this answer, could you please accept it?"

Answer 3

[James Tursa]

You might take a look at this FEX submission by Matt J:

http://www.mathworks.com/matlabcentral/fileexchange/29832-n-dimensional-sparse-arrays