Re: Curl

*To*: mathgroup at smc.vnet.net*Subject*: [mg34889] Re: [mg34875] Curl*From*: BobHanlon at aol.com*Date*: Wed, 12 Jun 2002 02:15:16 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

In a message dated 6/11/02 6:09:38 AM, jdeacon at jdl.co.uk writes: >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? > Needs["Calculus`VectorAnalysis`"]; SetCoordinates[Cartesian[x,y,z]]; Curl[{x*z,y*z,-y^2}] {-3*y, x, 0} Use an explicit multiplication operator and you won't have to remember to put a space between the variables. Bob Hanlon Chantilly, VA USA