Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 (MU) 9/23/84; site mulga.OZ Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!vax135!cornell!uw-beaver!tektronix!hplabs!qantel!dual!lll-crg!seismo!munnari!mulga!sgb From: sgb@mulga.OZ (Steven Bird) Newsgroups: net.math Subject: Re: The Perils of Nutrasweet: digits of precision Message-ID: <866@mulga.OZ> Date: Mon, 19-Aug-85 02:54:26 EDT Article-I.D.: mulga.866 Posted: Mon Aug 19 02:54:26 1985 Date-Received: Sun, 25-Aug-85 13:54:02 EDT References: <771@burl.UUCP> <394@petrus.UUCP> <182@steinmetz.UUCP> Reply-To: sgb@mulga.OZ (Steven Bird) Organization: Comp Sci, Melbourne Uni, Australia Lines: 23 > This is getting rather off the point, but some of you might like > this. During one of my interviews for college, I was asked a typical > stupid interview question: "What's the area of a table 3 meters wide by 4 > meters long?" I poked around with various counter-probes like, "Do you > mean the area of just the top surface, or the top and bottom combined?" and > then came up with the obvious answer; 12 meters^2. > Anyway, it turns out the "correct" answer is 1 * 10^1 meters^2; > since the initial data only had 1 digit of accuracy, that's all the final > answer can have. Getting even more off the point, suppose we were to compute 3*4 in base 12. The answer of course is 10(base 12) which has 1 significant figure as required. 10(base 12) translates to 12 +/- 6 (base 10) which I think is more acceptable than the 10 +/- 5 implied by 1 * 10^1 metres^2 above. Error analysis should be *independent* of the base used to represent numbers. For this reason I think there is something fundamentally wrong with the use of significant figures to express accuracy. -- Steven Bird. PHONE: +613 344-5229 (03 344-5229) UUCP: {seismo,ukc}!munnari!sgb mulga!sgb@decvax.uucp