Re: problem of evaluating SQRT
- To: mathgroup at smc.vnet.net
- Subject: [mg28004] Re: [mg27981] problem of evaluating SQRT
- From: BobHanlon at aol.com
- Date: Wed, 28 Mar 2001 02:40:32 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
In general the result is not zero. Even if x is real Simplify[Sqrt[x^2] - x , Element[x, Reals]] Abs[x] - x However, assuming that x is real and non-negative then Simplify[Sqrt[x^2] - x , x >= 0] 0 or Sqrt[x^2] - x // PowerExpand 0 Bob Hanlon In a message dated 2001/3/27 1:46:33 AM, phsoh at alum.mit.edu writes: >We have a question of how sqrt can be evaluated. > >In[1]:= >Sqrt[x^2] > >Out[1]= >(This part is just sqrt[X^2]) > >Below we expect the result to be zero but it isn't. How can we get the >correct answer in this case? > >In[2]:= >Sqrt[x^2] - x > >Out[2]= >(This part is -x + sqrt[x^2] ) >