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Re: Checking the sign of a Mathematical expression

• To: mathgroup at smc.vnet.net
• Subject: [mg66471] Re: Checking the sign of a Mathematical expression
• From: "Steve Luttrell" <steve_usenet at _removemefirst_luttrell.org.uk>
• Date: Sun, 14 May 2006 02:58:28 -0400 (EDT)
• References: <e3uodm$i9u$1@smc.vnet.net> <e418oq$h32$1@smc.vnet.net> <e43vov$8uq$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

"Paul Abbott" <paul at physics.uwa.edu.au> wrote in message 
news:e43vov$8uq$1 at smc.vnet.net...
> In article <e418oq$h32$1 at smc.vnet.net>,
> "Steve Luttrell" <steve_usenet at _removemefirst_luttrell.org.uk> wrote:
>
>> Here are two examples of what you want:
>>
>> Simplify[Sign[x^2],x>0]
>> 1
>>
>> Simplify[Sign[Sin[x]^2],0<x<Pi]
>> 1
>
> I think that Reduce is preferable:
>
>  Reduce[x^2 > 0, x]
>
>  Reduce[Sin[x]^2 > 0 && 0 <= x <= 2 Pi, x]
>
>  Reduce[Sin[x]^2 > 0, x, Reals]
>
> 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)
> AUSTRALIA                               http://physics.uwa.edu.au/~paul
>

Agreed. Sometimes I wonder what I was originally thinking of when I reread 
my posts. And I think I should have chosen better examples anyway!

Steve Luttrell
West Malvern, UK