Re: Sign Declaration
- To: mathgroup at smc.vnet.net
- Subject: [mg80282] Re: Sign Declaration
- From: Bhuvanesh <lalu_bhatt at yahoo.com>
- Date: Thu, 16 Aug 2007 04:52:52 -0400 (EDT)
Specifying the sign of an expression by using Sign[var]^=1 or x/:Sign[x]=1 is not recommended, as these have the potential to interact poorly with built-in functions. A better way is to use the assumptions mechanism:
In[1]:= $Assumptions = {Sign[x]==1};
In[2]:= Refine[Sign[x^2]]
Out[2]= 1
In[3]:= Simplify[Sign[x^2]]
Out[3]= 1
Bhuvanesh,
Wolfram Research