In Chapters 7 and 9 of the text, I described several iterative methods for solving a large linear system of equations.  The simplest of these, known as the Jacobi method, is also (not surprisingly) the slowest to converge.  A recent news story suggests that a simple modification of the Jacobi method can make it competitive with SOR and even CG.  The news story is here, and the article is here.  Once I have mastered the material in the article I will post a more complete discussion here.  And it is certainly the case that the treatment of the Jacobi method in any future editions of the text will be affected by this new work.