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MathGroup Archive 2007

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an expression with logs

  • To: mathgroup at smc.vnet.net
  • Subject: [mg75313] an expression with logs
  • From: dimitris <dimmechan at yahoo.com>
  • Date: Wed, 25 Apr 2007 05:30:16 -0400 (EDT)

Hello.

In[27]:=
oo = 5*Log[4/3] - 3*Log[3/2] - Log[2];

I want oo to take the form 4*(3*Log[2] - 2*Log[3])

I can think one workaround like

In[43]:=
PowerExpand[oo]
Collect[%, {Log[2], Log[3]}]
% /. Log[4] -> 2*Log[2]
Factor[%]

Out[43]=
-Log[2] - 3*(-Log[2] + Log[3]) + 5*(-Log[3] + Log[4])

Out[44]=
2*Log[2] - 8*Log[3] + 5*Log[4]

Out[45]=
12*Log[2] - 8*Log[3]

Out[46]=
4*(3*Log[2] - 2*Log[3])

But I am sure there is something smarter and more compact.

Any ideas?

Dimitris



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