Re: 1>0 gives False
- To: mathgroup at smc.vnet.net
- Subject: [mg73797] Re: [mg73758] 1>0 gives False
- From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
- Date: Wed, 28 Feb 2007 04:43:07 -0500 (EST)
- References: <200702271054.FAA24273@smc.vnet.net>
On 27 Feb 2007, at 11:54, dh wrote: > > > $Version: 5.1 for Microsoft Windows (October 25, 2004) > > Hello, > > can anyone explain the following: > > 1`2 > 0 > > False > > If we have 3 digits of precision: 1`3 we get the correct result. > > Daniel > > > This has come up a number of times so I don't want to repeat this here yet agian. See, for example, http://forums.wolfram.com/mathgroup/archive/2006/Feb/msg00088.html Note that: 1`2 ==0 so True 1`2 > 0 False This is a quirky aspect of significance arithemtic at very low precision. The solution is to avoid it. Significance arithmetic is intended for high precision computations which can serve as a substitute for exact computations when these are too slow to be realistic. Low precision numbers like 1'2 ar enot intended to model low precision empirical computations and are actually quite useless when used for this purpose. One should instead use machine precision numbers (or exact numbers when possible) and use bona fide Interval aritmetic to estimate errors, if that is needed. Andrzej Kozlowski
- References:
- 1>0 gives False
- From: dh <dh@metrohm.ch>
- 1>0 gives False