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Re: Re: Forcing a Derivative

  • To: mathgroup at
  • Subject: [mg50793] Re: [mg50778] Re: Forcing a Derivative
  • From: Murray Eisenberg <murray at>
  • Date: Tue, 21 Sep 2004 03:49:18 -0400 (EDT)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <cijej8$hlp$> <>
  • Reply-to: murray at
  • Sender: owner-wri-mathgroup at

Your answer, and those of others, just reinforces my complaint about 
this limitation of Mathematica today.  Why should one have to introduce 
what is, from a modern mathematical point of view, an extraneous extra 
variable, "x"?

A function f is an object; an "expression in x" such as f[x] is quite 
another.  Or at least it should be!

Klaus G wrote:

>>Derivative[2][f * g]
>>just puts a couple of primes on the product rather than actually computing the dervative.
>>Thanks for any insight.
>>Cheers, Scott
> Hi,
> f is NOT f[x], so please try:
> deriv = D[f[x]*g[x], {x, 2}]
> Collect[deriv, x]
> regards
> Klaus G.

Murray Eisenberg                     murray at
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305

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