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MathGroup Archive 1998

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Re: Re: Help please: Summing a list

  • To: mathgroup at smc.vnet.net
  • Subject: [mg13588] Re: [mg13555] Re: [mg13480] Help please: Summing a list
  • From: Jon Prudhomme <prudhomj at elwha.evergreen.edu>
  • Date: Mon, 3 Aug 1998 03:53:50 -0400
  • Sender: owner-wri-mathgroup at wolfram.com

Oops sorry, I should have said this:

PP=Table[Apply[Plus,Take[P,n]],{n,1,Length[P]}]

(That'll teach me to try it before I post it...)

On Sat, 1 Aug 1998, Jon Prudhomme wrote:

> 
> Rob, I think it would be easier to try this -
> 
> 	PP=Table[Apply[Plus,Take[P,n]],{n,1,i}]
> 
> Jon Prudhomme
> The Evergreen State College
> 
> On Sat, 1 Aug 1998, Keith S. Mersman wrote:
> 
> > Rob,
> > 
> > I think you want to do something like this:
> > 
> > First, set up your original table:
> > 
> > 	tab=Table[x,{x,0,110}]
> > 
> > Then, assign a name to each of these entries like:
> > 
> > 	Clear[P]; 
> > 	Table[P[i]=tab[[i]],{i,1,111}]
> > 
> > This, this let P[i] be the i-1 entry in the table (labeled tab)
> > 
> > Now, sum these values and label the totals:
> > 
> > 	Table[PP[i]=Sum[P[n],{n,1,i}],{i,1,111}]
> > 
> > This makes PP[i] be the sum of the first i entries of the orinal table.
> > 
> > Now, creata a new table with these values:
> > 
> > 	newtab=Table[PP[i],{i,1,111}]
> > 
> > Hence, newtab is now a list with the ith value as the sum as the sum of
> > the first i entries of tab.  Let me know if this is what you wanted.
> > 
> > 
> > On Sun, 26 Jul 1998 robpetersonSPAMME at iname.com wrote:
> > 
> > > I make a list of numbers, eg:
> > > 
> > > P=Table[6,{x,0,110}]; (I have a more interesting list to use later if I
> > > get this working)
> > > 
> > > Now I want to make another list PP in which each entry PP[[i]] is the
> > > sum of P's first i entries.  I try
> > > 
> > > PP[[i]]:=Sum[P[[n]],{n,0,i}];
> > > 
> > > At the definition, I get the following error: Part::"pspec": 
> > >     "Part specification \!\(n\) is neither an integer nor a list of
> > > integers."
> > > 
> > > I don't know how to make n an integer.  In the definition of Sum[], it
> > > seems n is an integer unless you add a forth parameter "di" in the
> > > specification list such as 
> > > Sum[f, {i, imin, imax, di}]
> > > 
> > > Can anyone help me to generate this second list?
> > > 
> > > Thanks, Rob
> > > 
> > > 
> > 
> > 
> > 
> 


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