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MathGroup Archive 2005

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Re: Re: Bug in 5.1??

  • To: mathgroup at smc.vnet.net
  • Subject: [mg54482] Re: [mg54448] Re: [mg54349] Bug in 5.1??
  • From: DrBob <drbob at bigfoot.com>
  • Date: Mon, 21 Feb 2005 03:44:49 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Duly noted.

Bobby

On Sun, 20 Feb 2005 22:04:51 +0100, Andrzej Kozlowski <akoz at mimuw.edu.pl> wrote:

> I never wrote this makes sense. I only pointed out that if you think it
> is a bug you should report it. On the other hand it has been a part of
> Mathematica since the first version I used, which was version 1.2, I
> think. Since then this issue has been discussed almost every year. From
> what has been explained, both on this list and in other places, it is a
> consequence of certain shortcuts that Significance arithmetic makes to
> achieve reasonable speed. It is harmless because nobody ever needs to
> compute anything with two digits of precision.
>
> Andrzej Kozlowski
>
>
> On 20 Feb 2005, at 17:58, DrBob wrote:
>
>> N[50000,2] should represent something between, say, 49500 and 50500,
>> both of which are positive. If it means something other than that,
>> please enlighten us!!
>>
>> Meanwhile, perhaps we can use Interval to interpret it:
>>
>> Interval[N[50000, 2]]//InputForm
>> Interval[
>>   {49488.`1.9955298983230858,
>>    50512.`2.0044245602121236}]
>>
>> Interval@N[50000,2]>0
>> True
>>
>> So I don't see how this makes sense:
>>
>> N[50000,2]>0
>> False
>>
>> Bobby
>>
>> On Sun, 20 Feb 2005 10:53:16 +0100, Andrzej Kozlowski
>> <akoz at mimuw.edu.pl> wrote:
>>
>>> *This message was transferred with a trial version of CommuniGate(tm)
>>> Pro*
>>> Then surely you must have filed a bug report as it would be
>>> irresponsible not to!
>>>
>>> Andrzej Kozlowski
>>>
>>> On 20 Feb 2005, at 06:10, DrBob wrote:
>>>
>>>> This behavior will find defenders, I'm sure, but it certainly looks
>>>> like a bug to ME.
>>>>
>>>> Bobby
>>>>
>>>> On Sat, 19 Feb 2005 02:31:49 -0500 (EST), Gehrmann, James E
>>>> <jgehrman at saclink.csus.edu> wrote:
>>>>
>>>>> I'm running Mathematica v. 5.1 under WinXP and had the following
>>>>> interaction with Mathematica:
>>>>> 5>0
>>>>>
>>>>> True
>>>>>
>>>>> 5.>0
>>>>>
>>>>> True
>>>>>
>>>>> N[5]>0
>>>>>
>>>>> True
>>>>>
>>>>> N[5,3]>0
>>>>>
>>>>> True
>>>>>
>>>>> N[5,2]>0
>>>>>
>>>>> False
>>>>>
>>>>> N[50000,2]>0
>>>>>
>>>>> False
>>>>>
>>>>> Are the last two results a bug or am I not understanding the N
>>>>> function?
>>>>>
>>>>> Thanks for you help.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> DrBob at bigfoot.com
>>>> www.eclecticdreams.net
>>>>
>>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>> --
>> DrBob at bigfoot.com
>> www.eclecticdreams.net
>>
>>
>
>
>
>



-- 
DrBob at bigfoot.com
www.eclecticdreams.net


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