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Re: Product and Summation sign

  • To: mathgroup at
  • Subject: [mg66814] Re: Product and Summation sign
  • From: "Steve Luttrell" <steve_usenet at>
  • Date: Wed, 31 May 2006 06:31:15 -0400 (EDT)
  • References: <e5h5d7$eo7$>
  • Sender: owner-wri-mathgroup at



"Sum[f, {i, imax}] evaluates the sum of the expressions f as evaluated for 
each i from 1 to imax. Sum[f, {i, imin, imax}] starts with i = imin. Sum[f, 
{i, imin, imax, di}] uses steps di. Sum[f, {i, imin, imax}, {j, jmin, jmax}, 
... ] evaluates a sum over multiple indices."

so the result that you obtained from Sum[x[i],{i,1,50}] was the correctly 
evaluated result.




"HoldForm[expr] prints as the expression expr, with expr maintained in an 
unevaluated form."

so to obtain the result that you wanted to see (i.e. one that is 
unevaluated) then you need to to evaluate


Steve Luttrell
West Malvern, UK

<actuary at> wrote in message news:e5h5d7$eo7$1 at
> While a Mathematica user for some time,  use has been limited to number
> crunching and not symbolic manipulations.  I started to remedy this
> over the weekend.
> I entered Sum[x[i],{i,1,50}] expecting to see a response with Summation
> sign.  Instead the output was x[1}+x[2]+x[3]+.....
> What do I need to do to get output that includes the Summation sign?
> StandardForm was checked.
> Thanks.
> Larry

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