RE: Lower Floor
- To: mathgroup at smc.vnet.net
- Subject: [mg39021] RE: [mg39004] Lower Floor
- From: "Wolf, Hartmut" <Hartmut.Wolf at t-systems.com>
- Date: Sat, 25 Jan 2003 01:23:39 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
>-----Original Message----- >From: André Giroux [mailto:giroux at dms.umontreal.ca] To: mathgroup at smc.vnet.net >Sent: Friday, January 24, 2003 11:06 AM >To: mathgroup at smc.vnet.net >Subject: [mg39021] [mg39004] Lower Floor > > >Hi All. >With Mathematica 4.1 on Windows98: >N[Log[8]/Log[2]] >3. >Floor[N[Log[8]/Log[2]]] >2 >Beware! > > André, that's not a problem of Mathematica, but we have to pose the right question: In[75]:= FullSimplify[Log[8]/Log[2]] Out[75]= 3 The exact answer! You might be interested to observe (e.g. set n = 1000): Length /@ Split@Table[Floor@(Divide @@ Log@SetPrecision[{8, 2}, p]), {p, n}] Or else, look at: In[92]:= Divide @@ Log@SetPrecision[{8, 2}, 60] // InputForm Out[92]//InputForm= 2.99999999999999999999999999999999999999999999999999999\ 9999999999999740815`59.7159 In[93]:= Divide @@ Log@SetPrecision[{8, 2}, 61] // InputForm Out[93]//InputForm= 3.00000000000000000000000000000000000000000000000000000\ 000000000000000000609051`60.7159 We shouldn't expect something much different from this. -- Hartmut Wolf