To specify the sparse matrix size when creating it, use the following syntax:
sparse(I,J,K,m,n)
where m is the number of rows and n is the number of columns.
That being said, this will of course create the sparse matrix from scratch each iteration using the I, J, K variables, so you will incur that overhead.
Changing the existing sparse matrix directly instead will also incur some overhead since the existing elements will have to be moved in memory. You will probably have to experiment to see which method is faster for you based on your particular matrix structure.
Question: When you update Q, do you simply modify existing non-zero values to different non-zero values, or do you insert/delete other non-zero values into the matrix? I.e., do you change the sparse matrix pattern at each iteration or does this sparse matrix pattern remain the same at each iteration?
