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Re: Possreps and numeric types

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Thu, 29 Mar 2007 17:44:30 GMT
Message-ID: <2WSOh.16999$PV3.175012@ursa-nb00s0.nbnet.nb.ca>


Gene Wirchenko wrote:

> Bob Badour <bbadour_at_pei.sympatico.ca> wrote:
> 

>>Gene Wirchenko wrote:
>>
>>>Bob Badour <bbadour_at_pei.sympatico.ca> wrote:
>>>
>>>>Gene Wirchenko wrote:
>>>>
>>>>>Bob Badour <bbadour_at_pei.sympatico.ca> wrote:
>>>>>
>>>>>[snip]
>>>>>
>>>>>>I admit I used epsilon somewhat sloppily and not necessarily with the
>>>>>>exact meaning used when discussing a particular floating-point
>>>>>>implementation. I used it to mean the distance to the representable
>>>>>>predecessor or successor of any representable rational value.
>>>>>
>>>>> That is incorrect. It is per
>>>>> http://en.wikipedia.org/wiki/Machine_epsilon
>>>>>In a floating-point system, epsilon is the smallest number such that
>>>>> 1 + epsilon > 1
>>>>>
>>>>>[snip]
>>>>
>>>>When you say the above is incorrect, are you saying I was not using
>>>>epsilon sloppily? Or are you saying I didn't use it to mean the distance
>>>>to the representable predecessor or successor of any representable
>>>>rational value?
>>>
>>> The definition of epsilon.
>>
>>Other than the "scaled by the exponent" bit, what exactly is the
>>difference? ie. If I subtracted one from the other, what answer would I get?
> 
>      If I am understanding you, other than that difference, none.  The
> answer would be garbage.

I really don't understand your objection. I noted I used the term sloppily and not as defined for floating point when I was discussing rational representations. Using the only definition I gave for the floating point version, the difference would be zero. The definitions are equivalent only stated differently. Received on Thu Mar 29 2007 - 12:44:30 CDT

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