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Re: Fourth Draft "Unsafe fp optimizations" project description.
- To: dewar at gnat dot com, paubert at iram dot es
- Subject: Re: Fourth Draft "Unsafe fp optimizations" project description.
- From: dewar at gnat dot com
- Date: Tue, 14 Aug 2001 09:55:36 -0400 (EDT)
- Cc: gcc at gcc dot gnu dot org, toon at moene dot indiv dot nluug dot nl,torvalds at transmeta dot com
<<I can send you a copy if Intel has cleaned up its web site. I don't have
the Ada requirements but I can't believe that anybody could seriously ask
for more accuracy (you never know until you read, however). The behaviour
on out-of-range inputs is another matter, although I believe that anybody
calling direct trigonometric functions (sin, cos and especially tan) with
large arguments should be aware of the risks he/she is taking.
Well Ada has very specific requirements (see ARM Annex G, even
for large arguments).
The issue is not accuracy in general, but the requirement that there not
be a single case in which the result from the hardware is outside ther
required model interval specified in the ARM. I looked at the Intel
documentation quite a while ago, and it was statistical in nature,
and did not have any absolute guarantees. That's what worried me.