[Ed Law]

Thanks for all your suggestions. I don't think Excel or my computer has those options. I really don't have time to investigate. My solution is start running the macro, walk away and do other things around the house and go back in an hour. I don't think it would need an hour but it was done when I got back.

The part that takes the longest time is A(T) * A. To not assemble the A matrix like you suggested would require a lot of reprogramming which I don't have time. Also when calculating the component OPR I have to solve A x = b 6 times. It may be better to just assemble A once instead of 6 times. As for sparse matrix solver, it will certainly help but A(T) x A takes a lot longer than the equation solving part. I am waiting for a VBA version of the sparse matrix solver to be available and then I will switch over from using Cholesky decomposition.