Re: problem of evaluating SQRT
- To: mathgroup at smc.vnet.net
- Subject: [mg27997] Re: problem of evaluating SQRT
- From: Ioan Alexandre Romoscanu <romoscanu at imes.mavt.ethz.ch>
- Date: Wed, 28 Mar 2001 02:40:25 -0500 (EST)
- Organization: Swiss Federal Institute of Technology (ETHZ)
- References: <99pd51$leb@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Pek I think that Mathematica considers Sqrt[x^2] = Abs[x]. If x = -2, Sqrt[x^2] - x gives 2 - (-2)=4, not 0. In other words, Sqrt[x^2] is not equal to x, and hence Sqrt[x^2] - x is not equal to 0. A. Pek wrote: > Hi, > > 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] ) > > Will really appreciate your help. Thanks. > > Pek -- ___________________________________________ alexandre ioan romoscanu - institut für mechanik CLA G31, eth zentrum, 8092 zürich, schweiz tel. +41 1 632 77 54, +41 76 323 63 05 fax.+41 1 632 11 45, romoscanu at imes.mavt.ethz.ch ___________________________________________