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MathGroup Archive 2005

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Re: Re: Re: odd mathematica blindspot

  • To: mathgroup at smc.vnet.net
  • Subject: [mg56560] Re: [mg56548] Re: [mg56502] Re: odd mathematica blindspot
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Fri, 29 Apr 2005 03:20:01 -0400 (EDT)
  • Reply-to: hanlonr at cox.net
  • Sender: owner-wri-mathgroup at wolfram.com

Rationalize[0.5]

1/2

%//N

0.5


Bob Hanlon

> 
> From: Edward Peschko <esp5 at pge.com>
To: mathgroup at smc.vnet.net
> Date: 2005/04/28 Thu AM 02:40:51 EDT
> Subject: [mg56560] [mg56548] Re: [mg56502] Re: odd mathematica blindspot
> 
> From: Edward Peschko <esp5 at pge.com>
To: mathgroup at smc.vnet.net
> Subject: [mg56560] [mg56548] Re: [mg56502] Re: odd mathematica blindspot
> Reply-To: 
> 
> On Tue, Apr 26, 2005 at 09:53:49PM -0400, Skirmantas wrote:
> > Hi Ed,
> > 
> > By definition, 9999999999999/10000000000000 is an exact rational 
number, whereas 0.5 is an approximate real number:
> 
> Well, that's completely unintuitive..  I understand it, but it still rubs me the 
> wrong way for some reason. '.5' on paper means that to me - .5 - not 
.4999999999
> or .50000000001 or whatever internal representation the computer 
chooses.. In fact, 
> that's why I got Mathematica in the first place, to get away from this 
approximate
> stuff.
> 
> Why couldn't mathematica treat .5 as a string, make the internal calculation 
> and turn .5 into 5/10? Or, barring that, is there a conversion function for 
this 
> (going back and forth between rational and approximate real?
> 
> Ed
> 
> 


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