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infuriating Series[] question

  • To: mathgroup at
  • Subject: [mg17226] infuriating Series[] question
  • From: Peter Jay Salzman <psalzman at>
  • Date: Mon, 26 Apr 1999 01:20:56 -0400
  • Sender: owner-wri-mathgroup at

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

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?


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