Re: problem of evaluating SQRT
- To: mathgroup at smc.vnet.net
- Subject: [mg28021] Re: problem of evaluating SQRT
- From: Ignacio Rodriguez <ignacio at sgirmn.pluri.ucm.es>
- Date: Wed, 28 Mar 2001 02:40:53 -0500 (EST)
- References: <99pd51$leb@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Did you take into account that second degree algebraic equations have two possible solutions and that Sqrt[x^2] has two possible values: x and -x? 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 -- Ignacio Rodriguez Ramirez de Arellano Unidad de RMN Universidad Complutense Paseo Juan XXIII, 1 Madrid 28040, Spain Tel. 34-91-394-3288 Fax 34-91-394-3245 e-mail: ignacio at sgirmn.pluri.ucm.es