f77 performance under 3.3.1

[Keith Bierman fpgroup]

....
>"exception" is *not* an error, it is just an exceptional (unusual)

Kahan (primary force behind the ieee 754 effort) has a nice slide on
this

	exceptions are not errors. exceptions are not uncommon.
	... repeated 50 times....

There are perfectly "normal" applications that do nearly all their
computation very close to zero (solving for deviations from an
expected value, for example) ....

Many vendors (Sun and MIPS included) exclude denomalized support from
the hw, and this causes a non-trival class of users to have severe
performance problems. Fortunately, most applications which compute
things close to zero are perfectly happy with flush to zero
arithmetic. Rather than having two librarys, a run-time is handy (in
my experience). On suns's that is call abrupt_underflow(). 

My point in posting is to not allow the spirit of Kahan to be
disturbed ... floating point exceptions are not exceptional events ...
we should have picked a name sans connotations of frequency.

--
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Keith H. Bierman    kbierman at Eng.Sun.COM | khb at chiba.Eng.Sun.COM
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