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

• To: mathgroup at smc.vnet.net
• Subject: [mg69075] Is -1^(2/5) really undefined in R?
• From: Ben <ben.carbery at spam.me>
• Date: Tue, 29 Aug 2006 04:47:34 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

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

• Follow-Ups:
  • Re: Is -1^(2/5) really undefined in R?
    • From: Murray Eisenberg <murray@math.umass.edu>
  • Re: Is -1^(2/5) really undefined in R?
    • From: János <janos.lobb@yale.edu>