Re: a simplification problem

• To: mathgroup at smc.vnet.net
• Subject: [mg55352] Re: a simplification problem
• From: Paul Abbott <paul at physics.uwa.edu.au>
• Date: Sun, 20 Mar 2005 04:11:45 -0500 (EST)
• Organization: The University of Western Australia
• References: <200503161035.FAA23728@smc.vnet.net> <d1bgl8\$lpn\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```In article <d1bgl8\$lpn\$1 at smc.vnet.net>, DrBob <drbob at bigfoot.com>
wrote:

> If you mean, "How do I extract the real third root of -1?", here's a method:
>
> ComplexExpand[x /. Solve[x^3 == -1]]
>
> {-1, 1/2 + (I*Sqrt[3])/2, 1/2 - (I*Sqrt[3])/2}
>
> First@Select[%, FreeQ[#1, Complex] & ]
>
> -1

To extract the real third root of -1, how about

Root[#^3 + 1 & , 1]

Cheers,
Paul

--
Paul Abbott                                   Phone: +61 8 6488 2734
School of Physics, M013                         Fax: +61 8 6488 1014
The University of Western Australia      (CRICOS Provider No 00126G)
35 Stirling Highway
Crawley WA 6009                      mailto:paul at physics.uwa.edu.au
AUSTRALIA                            http://physics.uwa.edu.au/~paul

```

• Prev by Date: Re: String to numbers
• Next by Date: Re: filling in an array
• Previous by thread: Re: a simplification problem
• Next by thread: Re: a simplification problem