Very costly interpolation of UserExpression

[plugged]

Maybe take a look at these, and try to implement your code in C++, this will make it much faster than using a UserExpression, that uses python to do the computations

How to pass numpy array to compiled expression member variable?

Thanks Kamensky! Just to add: Using the Eigen::Ref<> template instead of py::array_t<> , pybind11 casts numpy arrays directly and also gives access to the Eigen library methods. i.e Change npArray definition to typedef Eigen::Ref<Eigen::VectorXd> npArray; arr declaration to npArray arr; and the constructor method to test_exp(npArray a) : dolfin::Expression(), arr(a) {} This can help in using Eigen Methods e.g arr.sum() in the eval method.

Pass Function to C++ expression

Thanks a lot, it works

CompiledSubdomain using C++ class

My goal is to speed up the evaluation of the SubDomain Gamma from dolfin import * mesh = UnitSquareMesh(50,50, 'left/right') PHI = FunctionSpace(mesh, 'CG', 1) phi_expr = Expression('2.0*(1.0 - x[0])*x[0] + 0.2 - x[1]', degree=2) phi = interpolate(phi_expr , PHI) File("phi_initial.pvd") << phi class Gamma(SubDomain): def inside(self, x, on_boundary): return phi(x) > 0.5 with a C++ expression as follows omega_out_code = """ #include <pybin…