Q:SetCoordinates[system] usage
- To: mathgroup at smc.vnet.net
- Subject: [mg7651] Q:SetCoordinates[system] usage
- From: sergio at scisun.sci.ccny.cuny.edu (Sergio Rojas)
- Date: Tue, 24 Jun 1997 03:36:16 -0400 (EDT)
- Organization: City College Of New York - Science
- Sender: owner-wri-mathgroup at wolfram.com
Hello guys,
(*
I have the following sequence in Mathematica
In[3]:= $Version
Out[3]= DEC OSF/1 Alpha 2.2 (September 9, 1994)
*)
Needs["Calculus`VectorAnalysis`"];
a = {Derivative[1, 0][PHI][r, phi], Derivative[0, 1][PHI][r, phi]/r, 0}
b = {0, 0, 1}
aXb = Simplify[CrossProduct[a,b]]
(**********************
In this form, aXb has the expected value:
(0,1)
PHI [r, phi] (1,0)
Out[20]= {----------------, -PHI [r, phi], 0}
r
********************)
(* However, by doing: *)
Clear[aXb];
SetCoordinates[Cylindrical[r,phi,z]];
aXb = Simplify[CrossProduct[a,b]]
(**********************
aXb has the weird looking output:
(1,0) 2
Out[28]= {Sqrt[PHI [r, phi] ],
(0,1)
PHI [r, phi] (1,0)
> ArcTan[Sin[----------------] PHI [r, phi],
r
(0,1)
PHI [r, phi] (1,0)
> -(Cos[----------------] PHI [r, phi])], 0}
r
********************)
(* Am I misusing SetCoordinates[Cylindrical[r,phi,z]] here ? *)
Rojas
E-mail: sergio at scisun.sci.ccny.cuny.edu