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MathGroup Archive 1999

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Re: Rationalize[] in Mathematica3 vs. Mathematica4

  • To: mathgroup at smc.vnet.net
  • Subject: [mg20249] Re: Rationalize[] in Mathematica3 vs. Mathematica4
  • From: "Dana DeLouis" <dana2 at email.msn.com>
  • Date: Fri, 8 Oct 1999 18:30:22 -0400
  • References: <7t8cjs$gdr@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

I get the same results in Mathematica 4.  I do not notice any documentation
differences either.
Is this another problem?? Add just 1 more zero in the middle of your
number...

Rationalize[0.60000000000000001,10^-50]
or..
Rationalize[0.60000000000000001]

then I get an exact answer of 3/5 !

If I add another 0 (or more) to the middle of your number, then It goes back
to giving rational answers.

Did you find a bug??

In Fact...
Rationalize[0.60000000000000003,10^-50]
gives 3/5

Rationalize[0.60000000000000004,10^-50]
gives
1351079888093186 / 2251799813488643


Gianluca Gorni <gorni at dimi.uniud.it> wrote in message
news:7t8cjs$gdr at smc.vnet.net...
>
> Hello!
>
> I have run Mathematica 4 on a program that I had tested with
> Mathematica 3, and I noticed funny outputs. I traced the
> problem to the function Rationalize[], which seems
> to be different in the two version.
>
> With the following input
>
>  In:    Rationalize[0.6000000000000001`]
>
> Mathematica 3 gives
>
>  Out:   3/5
>
> while Mathematica 4 gives
>
>  Out:   1351079888093186/2251799813488643
>
> Is this change in behaviour intentional?
>
> To get the same result as before from my program
> I had to write Rationalize[x, .001] instead of
> Rationalize[x].
>
>               Gianluca Gorni
>  | mailto:gorni at dimi.uniud.it      |
>  | http://www.dimi.uniud.it/~gorni |








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