RE: Simplify[Abs[x],x<0]]
- To: mathgroup at smc.vnet.net
- Subject: [mg39307] RE: [mg39303] Simplify[Abs[x],x<0]]
- From: "Florian Jaccard" <jaccardf at eicn.ch>
- Date: Tue, 11 Feb 2003 04:40:41 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Hello ! I don^t know why... But I also notices that it is better to make your own "abs" : myAbs[x_]:=Sqrt[x^2] This one is very good on real numbers ! but if you want to use for example FourierSeries or Laplacetransform, it is better to use the following : myAbs[x_]:=UnitStep[x]x-UnitStep[-x]x Meilleures salutations Florian Jaccard professeur de Mathématiques EICN-HES 7, av. de l'Hôtel-de-Ville 2400 Le Locle tél. centrale +41 32 930 30 30 tél. direct +41 32 930 35 52 e-mail : jaccardf at eicn.ch -----Message d'origine----- De : Uri Zwick [mailto:zwick at cs.tau.ac.il] Envoyé : lun., 10. février 2003 07:08 À : mathgroup at smc.vnet.net Objet : [mg39303] Simplify[Abs[x],x<0]] Hi, Simplify[ Abs[x] , x>0 ] returns x. But, Simplify[ Abs[x] , x<0] returns Abs[x], and not -x. Why is that? Uri