Re: Is -1^(2/5) really undefined in R?

*To*: mathgroup at smc.vnet.net*Subject*: [mg69097] Re: [mg69075] Is -1^(2/5) really undefined in R?*From*: János <janos.lobb at yale.edu>*Date*: Wed, 30 Aug 2006 06:32:45 -0400 (EDT)*References*: <200608290847.EAA00784@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On Aug 29, 2006, at 4:47 AM, Ben wrote: > Is -1^(2/5) really undefined in R? > > Mathematica seems to think so, I guess since it looks like a > negative square root, but > > -1^(2/5) = (-1^2)^(1/5) = 1^(1/5) = 1 > > Is this correct mathematically? > > cheers, > > BC On my machine: In[1]:= -1^(2/5) Out[1]= -1 In[6]:= (-1)^(2/5) Out[6]= (-1)^(2/5) I think your first equal sign is incorrect. it should be -(1)^2^ (1/5), but hey, I was never good in mathematics :) János

**References**:**Is -1^(2/5) really undefined in R?***From:*Ben <ben.carbery@spam.me>