Re: Problems evaluating Grad

*To*: mathgroup at smc.vnet.net*Subject*: [mg39393] Re: Problems evaluating Grad*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Fri, 14 Feb 2003 03:17:34 -0500 (EST)*Organization*: Universitaet Leipzig*References*: <b2fpvg$k66$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de*Sender*: owner-wri-mathgroup at wolfram.com

Hi, the answer of In[]:= <<Calculus`VectorAnalysis` In[]:= f[x_,y_]:=x+y; Grad[f[a,b]] is Out[]={0,0,0} because a, and b don't depend on x,y,z If Mathematica does not find a rule, that apply to an expression it leave the expression unchanged and if nothing happen you have rpbably not loaded the Calculus`VectorAnalysis` package. Regards Jens Konrad Den Ende wrote: > > I'd like to detrmine Grad to a function so i go: > <<Calculus`VectorAnalysis` > f[x_,y_]:=x+y > > Grad[f[a,b]] > > I get no errors, but the answer is simply the same thing > that i asked, as if no computation was done. What do i > do wrong? > > Also - when i evaluated the examples in Help i got the same > behavior. The answer that already is there gets exchanged > to something else upon my evaluation. Namely, the question > itself. What is that?! > > -- > > Vänligen > Konrad > --------------------------------------------------- > phone #1: (+46/0) 708 - 70 73 92 > phone #2: (+46/0) 704 - 79 96 95 > url: http://konrads.webbsida.com > e-mail: chamsterkonrad at bigfoot.com > ----------------------------------- > > Sleep - thing used by ineffective people > as a substitute for coffee > > Ambition - a poor excuse for not having > enough sence to be lazy > ---------------------------------------------------