Re: Re: Automatic expansion of Log[a^n] for a,nexplicit positive integers?

*To*: mathgroup at smc.vnet.net*Subject*: [mg28255] Re: [mg28229] Re: [mg28180] Automatic expansion of Log[a^n] for a,nexplicit positive integers?*From*: Tomas Garza <tgarza01 at prodigy.net.mx>*Date*: Fri, 6 Apr 2001 01:53:03 -0400 (EDT)*References*: <Pine.LNX.4.30.0104051017290.3276-100000@carmen.nikhef.nl>*Sender*: owner-wri-mathgroup at wolfram.com

Dear Mianlai, You are absolutely right and I am absolutely wrong. This happens when one talks before thinking. Thanks, Tomas ----- Original Message ----- From: "Mianlai Zhou" <lailai at carmen.nikhef.nl> To: mathgroup at smc.vnet.net Subject: [mg28255] Re: [mg28229] Re: [mg28180] Automatic expansion of Log[a^n] for a,nexplicit positive integers? > Dear Tomas, > > By the way, there is problem in your definition of lg. In your code you > tested for all cases that Mod[n, 2] == 0, and returned Log[2] times the > power of 2 whenever it is true. So lg[6] will give the answer Log[2]. > Apparently it is wrong. > > Regards, > Mianlai > > > On Thu, 5 Apr 2001, Tomas Garza wrote: > > > > > If you are only concerned about powers of 2, then you may define the > > > functiion lg and use it always instead of Log: > > > > > > In[1]:= > > > lg[n_] := If[Mod[n, 2] == 0, IntegerExponent[n, 2]*Log[2], Log[n]] > > > > > > Then, e.g., > > > > > > In[1]:= > > > {lg[2], lg[4], lg[8], lg[16], lg[32], lg[3]} > > > Out[1]= > > > {Log[2], 2 Log[2], 3 Log[2], 4 Log[2], 5 Log[2], Log[3]} > > > > > > Tomas Garza > > > Mexico City > > > ----- Original Message ----- > > > From: "Harald Anlauf" <anlauf at hep.tu-darmstadt.de> To: mathgroup at smc.vnet.net > > > To: mathgroup at smc.vnet.net > > > Subject: [mg28255] [mg28229] [mg28180] Automatic expansion of Log[a^n] for a,n explicit positive > > > integers? > > > > > > > > > > Hi, > > > > > > > > is there a way to force Mathematica 4.0 to always expand expressions like > > > > > > > > Log[4], Log[8], Log[16], etc. to 2*Log[2] etc. > > > > > > > > automatically? > > > > > > > > It is very annoying to have such logarithms expanded manually each > > > > time they pop up again... > > > > > > > > PowerExpand[] apparently does not help/work. > > > > > > > > -- > > > > Ciao, > > > > -ha > > > > > > > > > > > > > > > > >