[Bug math/22906] new version of exp doesn't always round correctly

["woodard at redhat dot com" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=22906

--- Comment #5 from Ben Woodard <woodard at redhat dot com> ---
I've been talking this over with the customer and provided them the data that I
posted below about the level of performance with the different implementations
and how close to correctly rounded it is and after showing them the comparison
of the speeds and the accuracy and in particular showing them that at least one
of the libraries that they have been using also has the same not perfectly
rounded to the last bit, characteristic they replied:

"I believe we are happy with the 1ULP performance and functionality.   Although
the climate guys may want the 1/2ULP for crlibm, I think this should only be an
option, not the default math library.   They can explicitly link it in if they
want it." The climate guys do need last bit accuracy which is where the idea of
the butterfly effect came from. 

I believe this case is good for future reference because it demonstrates the
relative accuracy, states the position, and shows the trade offs being made.

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