On Sun, 11 Jul 2010 00:50:30 -0400, "(Rebecca) Xuefei YUAN" <xy2102 at columbia.edu> wrote: > Dear all, > > If testing the hand coded Jacobian, the ratio is 1e-10, but the > difference is 1e-4, would this be some mistakes in Jacobian? This is fine, it just means that your matrix hasn't been scaled to O(1). Jed