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Re: infuriating Series[] question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg17284] Re: infuriating Series[] question
  • From: Pierre infelta <pierre.infelta at epfl.ch>
  • Date: Fri, 30 Apr 1999 23:22:21 -0400
  • Organization: EPFL
  • References: <7g0spa$dvc@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

may be you want to try

 g[f_[x],x_] := Series[ f[x], {x,0,10} ]

and insert something known for f[x]
g[Sin[x],x] 


to force evaluation of the numeraical coeffs you can also try

N[g[Sin[x|,x]

Peter Jay Salzman wrote:
> 
> Dear all,
> 
> I'm trying to develop very high order difference equations, and want to use
> Mathematica to save me from calculating tons of quantities like 5^10 / 7!
> 
> If I define:
>    g[x_] := Series[ f[x], {x,0,10} ]
> 
> And try to compute stuff like:
> 
>    g[5*h] or g[10*h]
> 
> It gives me the right answer, but i get terms like
> 
>    f'''''[0] * (5 x)^(10) / 10!
> 
> The whole point in using Mathematica is so that I don't have to calculate things
> which look like 5^10 / 10!   (that's factorial, of course, not me being
> emphatic).
> 
> Even when I try things like // Simplify or // FullSimplify, Mathematica refuses to
> simplify these rational coefficients.   One thing I've learned is that Mathematica
> can do anything -- but figuring out how to do the something is often
> completely not obvious to a nominal user like me.
> 
> Can someone tell me the secret here?
> 
> Pete
> 
> --
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