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Re: Simplify Oddity

  • To: mathgroup at smc.vnet.net
  • Subject: [mg59405] Re: [mg59399] Simplify Oddity
  • From: Andrzej Kozlowski <akozlowski at gmail.com>
  • Date: Mon, 8 Aug 2005 06:17:08 -0400 (EDT)
  • References: <200508080734.DAA03493@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

On 8 Aug 2005, at 09:34, AES wrote:



> I'm supposing that the following rather odd result has something to do
> with Mathematica being concerned that g or r (or k?) might be complex
> numbers?
>
>    In[151] :=
>
>          f1 = g (g/r)^(k-1);
>
>          f2 = g^k/r^(k-1);
>
>          f1/f2 // FullSimplify
>
>    Out[151] =  g^(-k)  (g/r)^k   r^k
>
> But shouldn't Mathematic be able to simplify this to unity  
> nonetheless?
> -- maybe without even invoking Simplify?
>
>
>
>


Not really. For example:


f1 = g (g/r)^(k-1);

f2 = g^k/r^(k-1);

g = -I; r = -3; k = 1/2;


f1/f2

-1


However (with fresh Kernel)


In[1]:=
f1 = g (g/r)^(k-1);

In[2]:=
f2 = g^k/r^(k-1);

In[3]:=
Simplify[f1/f2,Element[k,Integers]]

Out[3]=
1


Andrzej Kozlowski





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