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Re: Series[] command

  • To: mathgroup at smc.vnet.net
  • Subject: [mg55951] Re: [mg55939] Series[] command
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Tue, 12 Apr 2005 05:26:00 -0400 (EDT)
  • Reply-to: hanlonr at cox.net
  • Sender: owner-wri-mathgroup at wolfram.com

They are equal

Series[a*b,{a,ma,2},{b,mb,2}]//Normal

a (b-mb)+(a-ma) mb+ma mb

%//Simplify

a b

ma*mb+ma(b-mb)+mb(a-ma)+(a-ma)(b-mb)//Simplify

a b


Bob Hanlon

> 
> From: "Kris Preacher" <preacher at unc.edu>
To: mathgroup at smc.vnet.net
> Date: 2005/04/10 Sun PM 11:07:18 EDT
> To: mathgroup at smc.vnet.net
> Subject: [mg55951] [mg55939] Series[] command
> 
> Hi all,
> 
> I need to obtain the second-order Taylor series expansion of a*b around 
the
> points ma and mb. I thought Mathematica's Series[] command would do the
> trick, but no. The correct answer is:
> 
> ma*mb + ma(b-mb) + mb(a-ma) + (a-ma)(b-mb)
> 
> Mathematica gives:
> 
> b(a-ma) + ma(b-mb) + ma*mb
> 
> Whaddup??
> 
> Thanks,
> Kris Preacher
> UNC
> 
> 
> 


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