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=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,6828bb58accfa664 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2002-11-12 01:40:25 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!logbridge.uoregon.edu!xmission!news-out.spamkiller.net!propagator2-maxim!news-in.spamkiller.net!news02.tsnz.net!newsfeed01.tsnz.net!news.xtra.co.nz!53ab2750!not-for-mail From: "AG" Newsgroups: comp.lang.ada References: Subject: Re: Conditional types? X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Message-ID: <904A9.7105$8o1.1165601@news.xtra.co.nz> Date: Tue, 12 Nov 2002 22:41:12 -0800 NNTP-Posting-Host: 210.54.73.179 X-Complaints-To: newsadmin@xtra.co.nz X-Trace: news.xtra.co.nz 1037094021 210.54.73.179 (Tue, 12 Nov 2002 22:40:21 NZDT) NNTP-Posting-Date: Tue, 12 Nov 2002 22:40:21 NZDT Organization: Xtra Xref: archiver1.google.com comp.lang.ada:30753 Date: 2002-11-12T22:41:12-08:00 List-Id: "Dennis Lee Bieber" wrote in message news:emomqa.0d4.ln@beastie.ix.netcom.com... > 0x80 (just to keep the numbers small) could be signed -128, unsigned > +123 -- without some additional information the bit pattern tells one > nothing. However, that number can't be the result (assuming 8-bit signed numbers) of something like: X := -Y *if* you know that all possible Y values are positive. So, if inside a large body of data you find a single pattern like that, it must mean that one of the assumptions was incorrect: either the Ys can be negative (and, on top, the negation works like that) or the operation performed was something different from the simple negation. Or, maybe, the Ys encoding was different. All of that is info - eliminating the possibilities. All derived from a single 8-bit pattern too [Well, that last one isn't really true of course since it did involve quite a bit of extra info, but that single 8-bit pattern was the test that allowed to make a choice between theories about what the data and it's handling are]. > > You /might/ be able to identify that /some/ patterns are not /valid/ > floats, but that is the limit.