Re: Curl

*To*: mathgroup at smc.vnet.net*Subject*: [mg34907] Re: Curl*From*: lalu_bhatt at yahoo.com (Bhuvanesh)*Date*: Wed, 12 Jun 2002 02:15:45 -0400 (EDT)*References*: <ae4f76$9d2$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

John Deacon <jdeacon at jdl.co.uk> wrote: > I must be getting the coordinate system wrong. I want to > calculate something like curl F where > F(x,y,z) = ixz + jyz + ky^2 > where i, j and k are the unit vectors in the x, y and z > directions respectively. > > << Calculus`VectorAnalysis` > SetCoordinates[Cartesian[x, y, z ]] > Curl[{xz, yz, -y^2}] > produces > {-2 y, 0, 0} > Yet I would swear it should be -3yi + xj > > What am I doing wrong? > > John You need a space or a multiplication sign between variables that you are multiplying (i.e. xz is a single variable, while x*z is Times[x,z]). In[1]:= <<Calculus`VectorAnalysis` In[2]:= SetCoordinates[Cartesian[x, y, z]] Out[2]= Cartesian[x, y, z] In[3]:= Curl[{x*z, y*z, -y^2}] Out[3]= {-3 y, x, 0} -- Bhuvanesh, Wolfram Research.