Function philosophy

[Tim Peters]

> [much interesting stuff deleted, just cuz i have nothing equally
>  interesting to add]

> ...
> And I definitely prefer myself routines that can be seen as black
> boxes that think their arguments are exact and do the best possible.

All right:  I take this as absolute evidence that all people who know what
they're doing are in complete agreement <smile>.

So is it (finally) time to nudge standards and manufacturers to catch up
to good current practice?  Several efficient approaches for achieving
error bounds strictly less than 1 ulp are known now (at least for all the
workhorse functions (trigonometrics, logs, exponentials)), and they're
becoming widespread.  Who would object if a standard committee screwed up
a bit of courage and insisted on < 1 ulp error for such functions?

I don't know, but it would be interesting to find out.  The adoption of
such a requirement would go a long way toward reducing confusion and
insanity (e.g., that's enough to guarantee |cos(x)| <= 1 and cos(0) ==
1).  And it would give me a defense against the next complaint that
sin(987492874*3.14) didn't return 0.0 <0.5 grin>.

eternally-surprised-that-users-put-up-with-exactly-the-wrong-things-
   ly y'rs  - tim

Tim Peters   timaksr.com
not speaking for Kendall Square Research Corp