Re: combining Log[] terms
- To: mathgroup at smc.vnet.net
- Subject: [mg30492] Re: combining Log[] terms
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Fri, 24 Aug 2001 04:05:52 -0400 (EDT)
- Organization: Universitaet Leipzig
- References: <9m281v$h28$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
because Log[a]-Log[b] == Log[a/b]
is only valid for a>0 and b>0. It
is not correct for negative or complex
arguments. If you tell Mathematica
that a>0 and b>0 it will transform
the expression
In[]:=Simplify[Log[a] - Log[b], Element[{a, b}, Reals] && a > 0 && b >
0]
Out[]=Log[a/b]
Regards
Jens
Nicolas Bock wrote:
>
> Is there a function that combines terms like
>
> Log[a] - Log[b]
>
> to
>
> Log[a/b]?
>
> I couldn't find anything so far in the documentation regarding the
> Log[] function, only some references to Collect[], which does
> something similar to what I want for powers of a given expression.
>
> Thanks already for you help,
>
> nick