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MathGroup Archive 2006

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Re: Mathematica Question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg66404] Re: [mg66358] Mathematica Question
  • From: "Chris Chiasson" <chris at chiasson.name>
  • Date: Thu, 11 May 2006 02:16:31 -0400 (EDT)
  • References: <200605101034.GAA21918@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

In[2]:=
Positive[x^2 + y]
Out[2]=
Positive[x^2 + y]
In[3]:=
Refine[%, x > 0 && y > 0]
Out[3]=
True
In[4]:=
Information["$Assumptions",
  LongForm -> False]
"$Assumptions is the default setting \
for the Assumptions option used in \
such functions as Simplify, Refine \
and Integrate."*Button[More\[Ellipsis],
   ButtonData :> "$Assumptions",
   Active -> True, ButtonStyle ->
    "RefGuideLink"]
In[5]:=
$Assumptions = {z > 0}
Out[5]=
{z > 0}
In[6]:=
Positive[z]
Out[6]=
Positive[z]
In[7]:=
Refine[Positive[z]]
Out[7]=
True

On 5/10/06, Bharat Bhole <bbhole at gmail.com> wrote:
> Hello:
>
> Is there a way in Mathematica to check whether an algebraic expression is
> positive or negative, and a way to specify conditions on the variables in
> the expression? For example, is there a way to check whether x^2 is positive
> for any real x? I want to check this for a complicated
> expression...basically the sign of the second derivative of a function.
>
> Thank you very much for your help.
>
> Bharat.
>
>
>


--
http://chris.chiasson.name/


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