Unfortunately to discuss under what
circumstances a splitting of A into M
minus N has the property that for some norm M inverse N is less than one requires
us to learn a little bit about
eigenvalues.  And the spectral radius of
the matrix comes in.  And that's a future
topic in this course.  So we're going to
defer on that. However, you can sorta 
contemplate under what circumstances is
M inverse N in norm small. Okay?  What is
the best way of splitting A into M and N
such that you converge in the fewest
iterations? Think about it.
