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f = function('f')
function('f')
 B=Manifold(2,'B',start_index=1)
 
B=Manifold(2,'B',start_index=1)
 
polar.<r,phi> polar.<R,Phi> = B.chart(R'R:(0,+oo) Phi:(0,2*pi):\Phi')Phi:(0,2*pi):\Phi')
  
G = B.riemannian_metric('G')B.riemannian_metric('G')
 G[1,1]=diff(f(R),R)
 
G[1,1]=diff(f(R),R)G[2,2]=f(R)^2
 nabla=G.connection()
 
G[2,2]=f(R)^2S=B.tensor_field(1,1)
 S[1,1]=R^(0.5)
 
nabla=G.connection()S[2,2]=R^3
 S.display()
 
S=B.tensor_field(1,1)nabla(S)
  
S[1,1]=R^(0.5)
 
S[2,2]=R^3
 
S.display()
 
nabla(S)
 
Error: TypeError: unable to convert R to an integerinteger

This Error doesn't occur either if I avoid the square root in S[1,1]=R^(0.5), for example by writing S[1,1]=R^(0.4) or if I avoid the dependence of the derivative of f in the first entry of the metric, for example by writing G[1,1]=f(R)^2.

This Error also doesn't occur in older Sage versions, for example Sage 7.1

Thanks a lot for help!