Re: Mathematica question
- To: mathgroup at smc.vnet.net
- Subject: [mg85064] Re: [mg85056] Mathematica question
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Sun, 27 Jan 2008 05:39:28 -0500 (EST)
- Reply-to: hanlonr at cox.net
expr = {m * Log[a] + m * Log[b], m * Log[a] - m * Log[b]};
Use Simplify
expr // Simplify
{m*(Log[a] + Log[b]), m*(Log[a] - Log[b])}
Alternatively, note that since
m * Log[a] - m * Log[b] // FullForm
Plus[Times[m,Log[a]],Times[-1,m,Log[b]]]
You should use either
expr /. {(m_)*Log[a_] + (m_)*Log[b_] -> m *(Log[a] + Log[b]),
Plus[Times[m_, Log[a_]], Times[-1, m_, Log[b_]]] ->
m*(Log[a] - Log[b])}
{m*(Log[a] + Log[b]), m*(Log[a] - Log[b])}
or
expr /. {m_ * Log[a_] + m_ * Log[b_] -> m *(Log[a] + Log[b]),
m_ * Log[a_] + Times[-1, m_, Log[b_]] ->
m*(Log[a] - Log[b])}
{m*(Log[a] + Log[b]), m*(Log[a] - Log[b])}
Bob Hanlon
---- None None <worm9056 at yahoo.com> wrote:
>
> Dear Sir
>
> I have a problem in mathematica. Consider the following function
> definition. EC1[expr_]:=expr//.{m_ Log[a_]+m_Log[ b_]=A6 m (Log[a]+Log[ b]),m_ Log[a_]-m_Log[ b_]=A6 m (Log[a]-Log[ b])}
> It works fine for "m Log[a]+mLog[b]", but it does not work for
> "m Log[a]-m Log[b]".
>
> Kindly guide me on resolving this issue.
>
> Kind regards
>