Sparse Matrix indexing

I need to built a sparse matrix for large matrix in order to avoid entering out of memory. Can a sparse matrix be build like: n=792;m=1000;j=2; A=sparse((n+3)*j+1,(3*n+m-1)*j); %then filling up this zero matrix with ones at certain rows and %columns like A(1:n*j,1:n*j)=eye(n*j,n*j);

I know this will increase the execution time but this will save me lot memory right?. Is there any other method I can perform

Answer 1

[Titus Edelhofer]

Hi Samir,

more or less that's the way to go. Take a look at the function speye, spdiags and the others under "See also" that help build up your matrix (in your example "eye" is a full matrix, whereas you want only to set the diagonal).

Titus

[Samir]

Thanks