Dear All, I would like to receive comments on the following problem. Suppose you have a matrix K and a matrix M. Matrix M is small compared to K. The problem I have is that matrix K is large and sparse. Matrix K is formed by assembly of several matrix M. So, I work with one matrix M whose size is changing every time that I need to perform an assembly in matrix K. I always know the size of matrix M just before performing the assembly. Because of matrix K is sparse and large, I just want to store non-zero elements. Here is the question: What would be the most efficient programming technique for the assembly stage, i.e., put matrix M into matrix K? Any comments is much appreciated. Thanks, Alejandro.