From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 109d8a,c7637cfdf68e766 X-Google-Attributes: gid109d8a,public X-Google-Thread: f43e6,c7637cfdf68e766 X-Google-Attributes: gidf43e6,public X-Google-Thread: 107079,c7637cfdf68e766 X-Google-Attributes: gid107079,public X-Google-Thread: 103376,c7637cfdf68e766 X-Google-Attributes: gid103376,public X-Google-Thread: f8362,c7637cfdf68e766 X-Google-Attributes: gidf8362,public From: jac@ibms48.scri.fsu.edu (Jim Carr) Subject: Re: floating point comparison Date: 1997/08/23 Message-ID: <5tnreu$9ac$1@news.fsu.edu>#1/1 X-Deja-AN: 268245771 Distribution: inet References: <5tk5he$7rq$1@news.fsu.edu> Organization: Supercomputer Computations Research Institute Newsgroups: comp.lang.ada,sci.math.num-analysis,comp.software-eng,comp.theory,sci.math Date: 1997-08-23T00:00:00+00:00 List-Id: dewar@merv.cs.nyu.edu (Robert Dewar) writes: > > There is no uncertaintly in the results of IEEE operations. The term "rounding error" and the alternative "rounding uncertainty" both refer to the fact that the precise and deterministic result of the conversion of a real number to a floating point value gives a bit pattern that *also* results from the precise and deterministic conversion of an uncountably infinite number of other real numbers. It implies no prejudice concerning whether this is good or bad, because it is inevitable. That is what it has in common with random (not systematic) measurement uncertainties, besides the fact that students are familiar with the latter and propagation of those uncertainties, that arise from the intrinsic limitations in the precision of measurement apparatus -- which is why I have found it to be a helpful alternative, a synonym as it were, when introducing the concept to non-math-major (usually CS) students. The difference is inevitable. It does exist. It has important consequences when interpreting the result of a calculation that is being used as a substitute for working with real numbers, a major reason computers exist. If you do not like the name, propose another -- but do not pretend that it does not happen. -- James A. Carr | Commercial e-mail is _NOT_ http://www.scri.fsu.edu/~jac/ | desired to this or any address Supercomputer Computations Res. Inst. | that resolves to my account Florida State, Tallahassee FL 32306 | for any reason at any time.