Re: Evaluating a sum from terms generated by the Array

*To*: mathgroup at smc.vnet.net*Subject*: [mg109519] Re: Evaluating a sum from terms generated by the Array*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Mon, 3 May 2010 06:11:31 -0400 (EDT)

Array[((-1)^(# + 1) (x)^#)/#! &, 3, 1] // Total x^3/6 - x^2/2 + x Plus @@ Array[((-1)^(# + 1) (x)^#)/#! &, 3, 1] x^3/6 - x^2/2 + x Sum[(-1)^(n + 1) x^n/n!, {n, 3}] x^3/6 - x^2/2 + x Series[1 - E^-x, {x, 0, 3}] // Normal x^3/6 - x^2/2 + x % == %% == %%% == %%%% True Bob Hanlon ---- davef <davidfrick2003 at yahoo.com> wrote: ============= I want to evaluate a sum from a series I created using the Array function. For example; I specify Array[((-1)^(# + 1) (x)^#)/# ! &, 3, 1 ] which gives me the following 3 terms of output: {x, -(x^2/2), x^3/6} Can anyone tell if and how I can turn these 3 terms into a sum to be evaluated?