Bug in Sum causes index variable to remain set?

*To*: mathgroup at smc.vnet.net*Subject*: [mg33838] Bug in Sum causes index variable to remain set?*From*: "Martin Jenkins" <lamarth at optushome.com.au>*Date*: Fri, 19 Apr 2002 02:28:35 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hello, I have found what appears to be a bug in Sum in Mathematica 4.0. I stumbled across is trying to sum an expression with subscripts. Anyway: In[1]:= n = 1; In[2]:= Sum[1, {f[x, 1], 1, 3}] Out[2]= 3 In[3]:= ?f In[4]:= Sum[1, {f[x, n], 1, 3}] Out[4]= 3 In[5]:= ?f In[6]:= Clear[f]; In[7]:= Sum[1, {f[x, 1*1], 1, 3}] Out[7]= 3 In[8]:= ?f The way that f gets set by the Sum to the final value is a bug is it not? I would guess that Sum unsets the literal expression f[x, n] or f[x, 1*1], rather than exactly what it set in the first place. I can get around this by f[x,n]=. whenever I use it... but I would rather not have a line with a comment saying "Mathematica bug work-around". Integrate works fine under similar circumstances. Thanks, Martin

**Follow-Ups**:**Re: Bug in Sum causes index variable to remain set?***From:*"Martin Jenkins" <lamarth@optushome.com.au>