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Re: Lower Floor

  • To: mathgroup at smc.vnet.net
  • Subject: [mg39042] Re: Lower Floor
  • From: Bill Rowe <listuser at earthlink.net>
  • Date: Sat, 25 Jan 2003 01:30:21 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

On 1/24/03 at 5:05 AM, giroux at dms.umontreal.ca (AndrÈ Giroux) wrote:

>With Mathematica 4.1 on Windows98:
>N[Log[8]/Log[2]] 
>3.
>Floor[N[Log[8]/Log[2]]] 
>2

This occurs since the N[Log[8]/Log[2]] gives you a machine precision number that is slightly less than 3

With Mathematica 4.2 on a TiBook running MacOS 10.2.3

Sign[N[Log[8]/Log[2]] - 3]
-1

A better way to express Log[8]/Log[2] would be Log[2,8] which gives an exact result of 3


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