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Re: Mathematica question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124805] Re: Mathematica question
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Tue, 7 Feb 2012 04:06:37 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201202060739.CAA10233@smc.vnet.net>
  • Reply-to: murray at math.umass.edu

Yikes: it seems to me that's exactly the sort of expression combining 
Postfix with the /@ special input form and pure functions that one 
should _not_ write!

The principal purpose of such special input forms should be to make 
expressions easier to read (and write), not more.

On 2/6/12 2:39 AM, Howie wrote:
> Let's say you've got an expression
>
> expr = {Sin[x] + x^2 - x^2*Cos[x], x^3 (1 + x^2) - x^3, x^4 - x^3}
>
> What does this mean?
>
> Table[expr[[j]] // FullSimplify[#, $assumptions]&  /@ #&  // Expand //
> @ #&, {j, 3}]
>
> I am new to Mathematica as far as these more complicated expressions
> are concerned.
>
> Can you explain symbol by symbol?
>
> I realize that the [[j]] is Part and that FullSimplify is applied //
> Postfix to expr, but I don't understand what $assumptions means (I'm
> assuming that these are some assumptions added to FullSimplify) but I
> do not know where these assumptions come from.  Are these assumptions
> the rest of the stuff on the right-hand side?
>
> In reality I have a potentially much more complicated form of the
> expr.
>
> Thanks!
>
>

-- 
Murray Eisenberg                     murray at math.umass.edu
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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