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MathGroup Archive 2004

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Re: RealDigits bug?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg46016] Re: RealDigits bug?
  • From: drbob at bigfoot.com (Bobby R. Treat)
  • Date: Mon, 2 Feb 2004 05:21:33 -0500 (EST)
  • References: <bv00g1$je7$1@smc.vnet.net> <bv2g1t$68$1@smc.vnet.net> <bv82tq$i97$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

No, Enrique asked for 6000 digits of precision, and that's what
Mathematica would give him. So, %MaxMachineNumber isn't the problem.

Bobby

adam.smith at hillsdale.edu (Adam Smith) wrote in message news:<bv82tq$i97$1 at smc.vnet.net>...
> Bobby,
> 
> What version of Mathematica are you using?  I am running Version 4.1
> and it does not include 10 in the Frequencies list
> 
> In[3]:=
> Frequencies[First[RealDigits[ pisot]]] 
> 
> 
> Out[3]=
> {{2089,0},{422,1},{427,2},{434,3},{467,4},{444,5},{452,6},{447,7},{437,
>     8},{381,9}}
> 
> 
> In response to Enrique.  I suspect that the failure is related to a
> misunderstanding of the N[] function.  In particular look in the Help
> for N[] and study the $MaxMachineNumber and $MaxPrecision.  Since your
> pisot is on the order of 10^3340, you may be running into truncation
> errors with N[].  On my machine $MaxMachineNumber is around 10^308.
> Since pisot is clearly much greater than this, I would expect
> truncation errors.
> 
> Adam Smith 
> 
> drbob at bigfoot.com (Bobby R. Treat) wrote in message news:<bv2g1t$68$1 at smc.vnet.net>...
> > I don't know whether the equality should be true, but it's very clear
> > that 10 isn't a base-10 digit!
> > 
> > Frequencies[First[RealDigits[
> >     pisot]]]
> > {{2086, 0}, {422, 1}, 
> >   {427, 2}, {434, 3}, 
> >   {467, 4}, {444, 5}, 
> >   {452, 6}, {447, 7}, 
> >   {437, 8}, {381, 9}, {3, 10}}
> > 
> > Bobby
> > 
> > Enrique Zeleny <ezeleny at fismat1.fcfm.buap.mx> wrote in message news:<bv00g1$je7$1 at smc.vnet.net>...
> > > This is wrong:
> > > 
> > > In[1]:= pisot = N[((1/3)*((1/2)*(27 + 3*Sqrt[69]))^(1/3) + (2/(27 +
> > > 3*Sqrt[69]))^(1/3))^27351, 6000];
> > > 
> > > In[2]:= pisot == FromDigits[RealDigits[pisot]]
> > > 
> > > Out[2]:= False
> > > 
> > > If you look at the value returned by RealDigits[pisot] contains three
> > > 10's!!!
> > > 
> > > 
> > > Enrique Zeleny
> > > Universidad Autonoma de Puebla
> > > Mexico


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