SkinnyGuy (697369) writes "While tech sites have been chasing each other's tails over a "new" Apple patent for a smart-pen-like device, the reality is much more interesting. This is the only story with the truth and insights from the actual inventor." Link to Original Source
We warn the reader in advance that the proof presented here depends on a
clever but highly unmotivated trick.
-- Howard Anton, "Elementary Linear Algebra"