How to assign a sparse matrix of dimension n x n into a 3d sparse matrix

For example S0=eye(V), where V= number of nodes in a graph & S(:,:,1)=S0 (assignment of S0 into S). How I can do the same representation when both S0 and S are sparse matrices?

Answer 1

[Guillaume]

Matlab sparse matrices are a 2D affair only,I'm afraid. There are FEX submissions that implement 3d sparse matrices however, e.g. ndSparse