Guidelines -- Isolate error
3.  Isolate the problem -- since the error is likely located
in a specific place in the system or program, large
sections of it are correct and should be removed from
consideration
o Isolating the problem to a specific procedure is best
o Verifying that parts thought to be correct are correct is
essential
o It is even possible to use binary search ...
Check if erroneous
results have been
produced here