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Re: fpu/e_expl.c for i686
- To: Andreas Jaeger <aj at suse dot de>
- Subject: Re: fpu/e_expl.c for i686
- From: Stephen L Moshier <moshier at mediaone dot net>
- Date: Mon, 7 May 2001 15:57:39 -0400 (EDT)
- cc: moshier at moshier dot ne dot mediaone dot net, libc-alpha at sources dot redhat dot com
- Reply-To: moshier at moshier dot ne dot mediaone dot net
> expl (1000) is .19e435 and can only be represented with long doubles.
> How much would the error be for expl (100)?
Instead of exp(x) the program computes exp(x(1 + dx)) where dx
is the relative input error introduced, in this case by the range
exp(x(1 + dx)) = exp(x) (1 + x dx + ...)
So if x is 100 and dx is 1/2 ulp, the relative error would be
about 50 ulps (long double ulps).