Re: NSum bug or am I doing something wrong?

*To*: mathgroup at smc.vnet.net*Subject*: [mg93904] Re: NSum bug or am I doing something wrong?*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Fri, 28 Nov 2008 05:07:59 -0500 (EST)

On 11/27/08 at 5:33 AM, ebpr08 at gmail.com (Ebpr Preb) wrote: >I'm getting imaginary answers for simple NSums of rational numbers. >The example below produces the issue in Mathematica 7: >NSum[(-1)^(k + 1)*(.2)^k, {k, 1, 32}] >gives me the result: >0.166667 + 1.1972*10^-44 I >When I switch to Sum the problem disappears. >Any hint? Use Chop, e.g. In[5]:= Chop@NSum[(-1)^(k + 1)*(.2)^k, {k, 1, 32}] Out[5]= 0.166667