mpf_sub bug (essentially same as reldiff bug)
Torbjorn Granlund
tg at swox.com
Wed May 12 13:44:06 CEST 2004
abbott at module.dima.unige.it writes:
I wrongly get 0 if
requested precision of a and b is 256
a = 1 and b = 1+2^(-129)
requested precision of rd is at most 64
I get the RIGHT answer if
a and b as before BUT
requested precision of rd is increased beyond 64
[I tried several values beyond 64, but not all of them :-]
Thanks. There is no need to investigate the envelope of a bug;
a plain test case demonstrating the bug is sufficient.
This miscomputation bug has apparently been around since the first
release with mpf. Not good.
--
Torbjörn
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