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=0.2 required=5.0 tests=BAYES_00,INVALID_MSGID, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 109fba,dad65365cb2b3396 X-Google-Attributes: gid109fba,public X-Google-Thread: 106c43,dad65365cb2b3396 X-Google-Attributes: gid106c43,public X-Google-Thread: fac41,dad65365cb2b3396 X-Google-Attributes: gidfac41,public X-Google-Thread: 1014db,dad65365cb2b3396 X-Google-Attributes: gid1014db,public X-Google-Thread: 103376,dad65365cb2b3396 X-Google-Attributes: gid103376,public From: fred@genesis.demon.co.uk (Lawrence Kirby) Subject: Re: The disturbing myth of Eiffel portability Date: 1996/11/26 Message-ID: <848976955snz@genesis.demon.co.uk>#1/1 X-Deja-AN: 200755239 references: <3294e64b.74799475@news2.ibm.net> <56t1m4$nis@bcrkh13.bnr.ca> <6LW663dk3RB@herold.franken.de> x-mail2news-user: fred@genesis.demon.co.uk x-mail2news-path: genesis.demon.co.uk organization: none reply-to: fred@genesis.demon.co.uk newsgroups: comp.lang.eiffel,comp.lang.ada,comp.lang.c,comp.lang.c++,comp.lang.object Date: 1996-11-26T00:00:00+00:00 List-Id: In article <6LW663dk3RB@herold.franken.de> jhd@herold.franken.de "Joachim Durchholz" writes: >fred@genesis.demon.co.uk wrote 24.11.96: > >> Financial calculations within (fairly generous) limits can use IEEE >> floating point and be *proven* correct barring bugs in the implementation. >> But bugs can affect integer calculations as well. > >However, integer bugs are less likely. After all, IEEE format is much more >complicated (at least in comparison to two's-complement integer). For IEEE >format, there is room for interpretation (really there isn't, but some >implementors behave as if there were). >E.g. the infamous Pentium bug was in the FPU, not in the ALU. Of course >this is jumping to conclusions from a statistically insignificant >sample... Doesn't the Pentium use the FPU for integer division? >> No >> format can represent general irrational quantities precisely. > >There is one - storing formulae instead of quantities :) > >Actually this is feasible - Mathematica and Co. do exactly this. This >allows them to compute as many digits as required on the fly, without loss >of precision from intermediate results. >(Of course there is still a round-off error, but it is always on the last >printed digits.) So Mathematica still have to evaluate the formulae at some point when you need a value and the issue of how you round is still there. -- ----------------------------------------- Lawrence Kirby | fred@genesis.demon.co.uk Wilts, England | 70734.126@compuserve.com -----------------------------------------