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Re: Grad in VectorAnalysis`

  • To: mathgroup at
  • Subject: [mg103840] Re: [mg103822] Grad in VectorAnalysis`
  • From: Bob Hanlon <hanlonr at>
  • Date: Fri, 9 Oct 2009 07:14:32 -0400 (EDT)
  • Reply-to: hanlonr at

Because the definition of f has only two arguments whereas it is called with three in the Grad.

Either call it with two or redefine it with three.

Bob Hanlon

---- Murray Eisenberg <murray at> wrote: 


   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...

   Grad[f[x, y, z]]  (* or even Grad[Evaluate[f[x,y,z]]]

... whereas the following does return it:

   Grad[x/(1 - x^2 - y^2)]

Murray Eisenberg                     murray at
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