Re: Simplify, Condition, Assuming and SetDelayd

*To*: mathgroup at smc.vnet.net*Subject*: [mg52370] Re: Simplify, Condition, Assuming and SetDelayd*From*: Paul Abbott <paul at physics.uwa.edu.au>*Date*: Thu, 25 Nov 2004 05:49:40 -0500 (EST)*Organization*: The University of Western Australia*References*: <co1e8d$sf0$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

In article <co1e8d$sf0$1 at smc.vnet.net>, alvaro diaz <alvarodiazfalconi at yahoo.com> wrote: > I'm write my Norm function with > > ... (etc) > DoubleBracketingBar[ z_ ] := Abs[z] /; Element[ z, > Complexes ]; > DoubleBracketingBar[ v_ ] := Sqrt[v . Conjugate[v]] /; > Element[ v, Vectors ]; There is no Vectors domain in Mathematica. To add a domain see The Mathematica Journal 7(4): 450-451. Why not just use Norm? It automatically handles these two cases. If you like you can write DoubleBracketingBar := Norm > Then, i'm try to evaluate > > FullSimplify[DoubleBracketingBar[ z_ ] == Abs[z], z > ?¸ Complexes] > > but do not work. (This is, the answer is not True) Because the Condition is held. Try Trace[FullSimplify[DoubleBracketingBar[z] == Abs[z], Element[z , Complexes]] to see why. Cheers, Paul -- Paul Abbott Phone: +61 8 6488 2734 School of Physics, M013 Fax: +61 8 6488 1014 The University of Western Australia (CRICOS Provider No 00126G) 35 Stirling Highway Crawley WA 6009 mailto:paul at physics.uwa.edu.au AUSTRALIA http://physics.uwa.edu.au/~paul