Elementwise multiplication of functions cpp

Question

Hi,

I need to implement an elementwise multiplication of two functions on the same 3D mesh in C++. My first approach is to implement a class called CustomFunction based on dolfin::Function and implement the operator* as :

CustomFunction operator*(dolfin::Function func, dolfin::Mesh mesh){
        dolfin::Function f(this->function_space())

        for (dolfin::MeshEntityIterator e(mesh, 0); !e.end(); ++e)
        {
            auto tmp = func.vector();
            for (dolfin::MeshEntityIterator e(mesh, 1); !e.end(); ++e)
            {
                for (dolfin::MeshEntityIterator e(mesh, 2); !e.end(); ++e)
                {
                    f[e->index()] = (*this)[e->index()]*func[e->index()]
                }
            }
        }
    }

It is basically an iteration over each dimension and it does not work. Is there any better way to do this?

Thanks in advance,
Justus

Comments

Hi, the above is not to a way to go. Are the functions in the same function space?

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Yes they are in the same (mixed-) functionspace

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Consider using the following for inplace multiplication. To fill a new vector by a pointwise product of two other vectors you can use PETSc.