Error while trying to find the derivative of user-defined expression ["ufl.log.UFLException: Cannot determine geometric dimension from expression."]

mathematics
2

The problem is that UFL cannot automatically infer what domain w_r is defined on. You can specify it manually as a keyword argument, i.e.,

w_r = Expression("cos(theta)*(1.-(3./(2.*r))+(1./(2.*pow(r,3))))",
                 degree=2,r=r,theta=theta,
                 domain=mesh)

which gets rid of the error.

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