In old version fenics, SymPy is used for symbolic,such as “x, y = sym.symbols(’x[0], x[1]’)” . Now , in dolfinx v0.6.0,how to represent symbol “x ,y” and replace the sympy use in old version?
Depending on your use-case, it is often most common to use ufl.SpatialCoordinate(domain), as done in various tutorials:
https://jsdokken.com/dolfinx-tutorial/chapter1/membrane_code.html#defining-a-spatially-varying-load
https://jsdokken.com/dolfinx-tutorial/chapter2/nonlinpoisson_code.html#test-problem
https://jsdokken.com/dolfinx-tutorial/chapter3/multiple_dirichlet.html#setting-multiple-dirichlet-condition
https://jsdokken.com/dolfinx-tutorial/chapter4/newton-solver.html?highlight=spatialcoordinate#definition-of-residual-and-jacobian
etc
thank you very much !
I have a question , why use eval function in nonlinear poisson equation implementation,i.e. u_exact = lambda x: eval(str(u_ufl))
One reason is to show how to do interpolation with lambda functions.
It is just a way of avoiding writing
… = lambda x: 1 + x[0] + 2*x[1] twice