Re: Just another Mathematica "Gotcha"
- To: mathgroup at smc.vnet.net
- Subject: [mg120808] Re: Just another Mathematica "Gotcha"
- From: "Kevin J. McCann" <kjm at KevinMcCann.com>
- Date: Wed, 10 Aug 2011 06:49:57 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <j1r5d3$fi4$1@smc.vnet.net>
I think that in the first, Mathematica is applying your rule to Normal, not to
the output. Put parens around it (Series ...//Normal)/.b2->0 and it works.
Kevin
On 8/9/2011 7:24 AM, AES wrote:
> Seems as if the following two expression should yield the same output
> -- seems that way to me anyway -- but they don't. I'll hide the
> actual outputs down below so Mathematica gurus (or "ordinary users")
> can make their predictions as to which one does what.
>
> In[1]:= Series[a+(b1+b2)x,{x,0,1}] //Normal /.{b2->0}
>
> In[2]:= Series[a+(b1+b2)x,{x,0,1}] /.{b2->0} //Normal
>
> My conclusions:
>
> 1) By any normal rules of interpretation or ordinary interpretations
> of these statements, they both should do the same same thing.
>
> 2) This is just another Mathematica "Gotcha" -- and not a
> particularly forgivable one.
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> Out[1]= a+(b1+b2) x
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> Out[2]= a+b1 x
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