Peter,
I agree, the precision is 100 places.
Looking at Mathematica's result again, it appears to be formally
incorrect. There is no binary point in front of the binary bits!
Shouldn't the "-4" be "-104"?
Or does "RealDigits[0.036`100, 2, 100]" imply that one first
multiplies .036 by 2^100. Then the answer is formally correct. That
would really be confusing!
Bob
>Yes, i understand, but the PRECISION (if I use the term correctly) is
>100 places.
>
>Cheers,
>P.
>
>
>On 8/2/06, Bob Delaney <[EMAIL PROTECTED]> wrote:
>>Peter,
>>
>>Because the "-4" means times 2^(-4), your result represents .036
>>accurate to 104 places following the binary point.
>>
>>Bob
>>
>>
>>
>>
>>>I've often wondered about trying Maple (any good?).
>>>
>>>Anyway, here is a reply from Wolfram tech support, turns out I wasn't
>>>using Mathematica correctly (a common occurrence with me, not a simple
>>>app to use). Os other were correct, 0.036 is not base-2
>>>representable, and this explains the integer round-down "error" first
>>>reported in this thread.
>>>
>>>======
>>>I believe Mathematica is working correctly.
>>>
>>>As specified in help of RealDigits, RealDigits[x]normally returns a list of
>>>digits whose length is equal to Precision[x].
>>>
>>>Please use the correct precision.
>>>
>> >RealDigits[0.036`100, 2, 100]
>>>
>>>returns:
>>>
>>>{{1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 1, 1, 0, 0,
>>>0,
>>> 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1,
>>>1,
>>> 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 0, 0,
>>>1,
>>> 1, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1,
>>>1,
>>> 0, 0, 1}, -4}
>>>
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>
>--
>-------------------------------------------------------------------------------
>Peter K. Stys, MD
>Professor of Medicine(Neurology), Senior Scientist
>Ottawa Health Research Institute, Div. of Neuroscience
>Ottawa Hospital / University of Ottawa
>Ontario, CANADA
>tel: (613)761-5444
>fax: (613)761-5330
>http://www.ohri.ca/profiles/stys.asp
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