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Groups > comp.soft-sys.math.mathematica > #16568
| From | Bill Rowe <readnews@sbcglobal.net> |
|---|---|
| Newsgroups | comp.soft-sys.math.mathematica |
| Subject | Re: Possible bug in Floor function? |
| Date | 2014-02-16 04:02 +0000 |
| Message-ID | <ldpd8v$6n8$1@smc.vnet.net> (permalink) |
| Organization | Time-Warner Telecom |
On 2/15/14 at 4:02 AM, s.nesseris@gmail.com (psycho_dad) wrote:
>I think I may have stumbled upon a possible bug in Floor. Evaluating
>the following gives the correct result:
>Floor[Log[10, 100.]]
>2
>Evaluating it with a replacement and //N gives a message and the
>wrong result:
>Floor[Log[10, x]] /. x -> 100 // N
>1
The problem isn't with Floor. The issue is simply the usage of
machine precision arithmetic. That is
In[11]:= RealDigits[Log[10, x] /. x -> 100 // N]
Out[11]= {{1,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9},1}
As you can see, the result is just slightly less than 2. So, the
result Floor returns is correct
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Re: Possible bug in Floor function? Bill Rowe <readnews@sbcglobal.net> - 2014-02-16 04:02 +0000 Re: Possible bug in Floor function? Richard Fateman <fateman@cs.berkeley.edu> - 2014-02-18 03:30 +0000
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