Re: Grad in VectorAnalysis`

*To*: mathgroup at smc.vnet.net*Subject*: [mg103846] Re: [mg103822] Grad in VectorAnalysis`*From*: David Bevan <david.bevan at pb.com>*Date*: Fri, 9 Oct 2009 07:15:39 -0400 (EDT)*References*: <200910081149.HAA13507@smc.vnet.net>

It looks to me like you haven't defined f[x, y, z]. I think you'll need f[x_, y_, z_] := ... You might also want to read up on "=" versus ":=". David %^> > -----Original Message----- > From: Murray Eisenberg [mailto:murray at math.umass.edu] > Sent: 8 October 2009 12:50 > To: mathgroup at smc.vnet.net > Subject: [mg103822] Grad in VectorAnalysis` > > After... > > Needs["VectorAnalysis`"] > SetCoordinates[Cartesian[x, y, z]] > > f[x_, y_] = x/(1 - x^2 - y^2) > > ... why does the following not actually return the formula for gradient..=

**References**:**Grad in VectorAnalysis`***From:*Murray Eisenberg <murray@math.umass.edu>