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Re: Rounding errors using doubles?
- To: slouken at devolution dot com, egcs at egcs dot cygnus dot com
- Subject: Re: Rounding errors using doubles?
- From: craig at jcb-sc dot com
- Date: 19 Mar 1999 17:29:11 -0000
- Cc: craig at jcb-sc dot com
- References: <E10O2lP-0006t2-00@roboto.devolution.com>
>If this doesn't work on other x86 CPUs, I'd like to know.
>Linux saves and restores the FPU flags on context switch, so this is
>safe to call in an individual program.
I've seen that kind of solution recommended before, and most/all
people who've used it seem to be happy with it.
The reason I don't like it as a general solution is that we don't
really know whether's there's any low-level numerical code lurking
down there that *assumes* the FPU modes are set to 80 bits, and
won't work correctly otherwise. It's therefore not a robust solution,
even though it might happen to be 100% effective. Whereas, an
option that's like -ffloat-store but affects *all* intermediate
computations *would* be robust, even if not 100% effective (in that
code not compiled with that option would still use 80-bit computations).
>BTW, I am on the list. :)
That's good to know: people can ignore my earlier email then.
tq vm, (burley)