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Question: non-orthogonal coordinates

Question:non-orthogonal coordinates

pfbuxton 4 Maple
coordinates linear
March 24 2010
0

Hi,

I wanted to use some non-orthogonal curve linear coordinates. I have entered them into maple by:

 

with(VectorCalculus):
assume(r>0,theta<=0,theta<Pi,0<=phi,phi<2*Pi);
AddCoordinates( 'myCoords1'[r,theta,phi], [(L+r*cos(theta)+Delta(r))*cos(phi),(L+r*cos(theta)+Delta(r))*sin(phi),r*sin(theta)] );
 

However this gives the warning:

Warning, the unit Vectors in the new coordinate system are not orthogonal, only added to global coordinate systems

 

 Then when I try and evaluate the gradient

Gradient(f(r, theta, phi), 'myCoords1'[r, theta, phi]);

 

I get:

Error, (in VectorCalculus:-Gradient) coordinate system `myCoords1` does not exist

 

Thanks for any help

Peter
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