RE: Is -1^(2/5) really undefined in R?
- To: mathgroup at smc.vnet.net
- Subject: [mg69112] RE: [mg69075] Is -1^(2/5) really undefined in R?
- From: "David Park" <djmp at earthlink.net>
- Date: Wed, 30 Aug 2006 06:33:53 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Solve[-1^2 == z^5, z]
{{z -> -1}, {z -> (-1)^(1/5)}, {z -> -(-1)^(2/5)},
{z -> (-1)^(3/5)}, {z -> -(-1)^(4/5)}}
David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/
From: Ben [mailto:ben.carbery at spam.me]
To: mathgroup at smc.vnet.net
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