Re: Help please: Summing a list
- To: mathgroup at smc.vnet.net
- Subject: [mg13499] Re: [mg13480] Help please: Summing a list
- From: Hugh Walker <hwalker at gvtc.com>
- Date: Fri, 31 Jul 1998 04:33:17 -0400
- Sender: owner-wri-mathgroup at wolfram.com
Rob Peterson at 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?
>
Hello Rob:
Here is another way to set up the sum function that should work OK.
P=Table[ Random [],{x , 1, 110}] ;
PP[i_] := Apply [ Plus,Take[ P, i ] ]
Cheers!
Hugh Walker
Professsor Emeritus
University of Houston
Gnarly Oaks