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Re: inexactness vs. exactness



Aubrey,

I'm not a mathematician, so be gentle.

Your idea that inexacts respresent intervals is interesting. However, consider a system that used IEEE doubles for inexacts but implemented a certain transcendental function with several ULPs of error. If I use this function, I will not necesarily get the inexact number that is closest to the exact result or, in other words, I will not get the inexact number that corresponds to the interval containing the exact result.

So, it would seem that if we accept that inexacts are intervals, we also force all of the transcendental functions to have 0 ULPs of error. Bear's suggestion that inexact numbers are simply results that might be wrong would make no similar restriction on the accuracy of these functions.

Do you agree with these conclusions?

Regards,

Alan
--
Dr Alan Watson
Centro de Radioastronomía y Astrofísica
Universidad Astronómico Nacional de México