Friday, August 30, 2013

that time of year again

This is the time of year for my annual reading of Lou Talman's nice little three-page paper "A Discontinuous Derivative".  You should give it a try.  It strains my mind, because I can't figure out how "differentiability implies local linearity" if there are functions running around out there with f'(0) defined even though the limit of f'(x) as x→0 does not exist.  So f is differentiable at zero, but I can't quite figure out why it is locally linear there.  Maybe next year.

Anyway, Lou Talman writes well, with a readable narrative and wit that many math papers lack.  He has a page full of papers just about AP Calculus topics