MathGroup Archive 2002

[Date Index] [Thread Index] [Author Index]

Search the Archive

bug in Sum?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg38062] bug in Sum?
  • From: Rob Pratt <rpratt at email.unc.edu>
  • Date: Thu, 28 Nov 2002 14:08:21 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

In[1]:= Binomial[0,0]

Out[1]= 1

I agree.


In[2]:= Sum[Binomial[0,k],{k,0,0}]

Out[2]= 1

I agree again.


In[3]:= Sum[Binomial[0,k],{k,0,n}]

Out[3]= 0

I disagree.  Should be If[n == 0, 1, 0].


In[4]:= Sum[Binomial[0,k],{k,0,Infinity}]

Out[4]= 0

I disagree.  Should be 1.


In[5]:= Sum[Binomial[n,k],{k,0,Infinity}]

         n
Out[5]= 2

I agree.  But inconsistent with Out[4].


Perhaps my desired result for In[3] is expecting too much.  After all, x/x
reduces to 1, not If[x == 0, Indeterminate, 1].  But Out[5] demonstrates
that Mathematica knows the binomial theorem.  It ought to be able to come
up with the correct result for In[4].


Rob Pratt
Department of Operations Research
The University of North Carolina at Chapel Hill

rpratt at email.unc.edu

http://www.unc.edu/~rpratt/




  • Prev by Date: Simple Concept I can't figure out! Making rules?
  • Next by Date: Producing ticks on left axis with axis labels
  • Previous by thread: Simple Concept I can't figure out! Making rules?
  • Next by thread: Producing ticks on left axis with axis labels