On Jan 8, 2019, at 11:58 PM, Tony Duell via cctalk
<cctalk at classiccmp.org> wrote:
...
IIRC one of the manuals for the HP15C had a chapter on 'Why this
calculator gives the wrong answers'. It covered things like rounding
errors.
-tony
That reminds me of a nice old quote.
"An electronic pocket calculator when used by a person unconversant with it will most
probably give a wrong answer in 9 decimal places" -- Dr. Anand Prakash, 9 May 1975
Understanding rounding errors is perhaps the most significant part of "numerical
methods", a subdivision of computer science not as widely known as it should be. I
remember learning of the work of a scientist at DEC whose work was all about this: making
the DEC math libraries not only efficient but accurate to the last bit. Apparently this
isn't anywhere near as common as it should be. And I wonder how many computer models
are used for answering important questions where the answers are significantly affected by
numerical errors. Do the authors of those models know about these considerations? Maybe.
Do the users of those models know? Probably not.
paul