Dear all,

I meet some problems on interpolation.

The following is the code:

solve LP(w,v)=

int2d(V1)(dx(w)*dx(v)+dy(w)*dy(v))

+int2d(V1)(dx(u2)*dx(v)*Xi+dy(u2)*dy(v)*Xi

+dx(u2)*v*dx(Xi)+dy(u2)*v*dy(Xi))

Here w,v are in the same FEM space V1, while Xi is in another FEM space V2.

Now I want to change the second integration to get this formula:

int2d(V1)(dx(u2)*dx(Ph(v*Xi))+dy(u2)*dy(Ph(v*Xi)), where Ph is the interpolation operator in V1 space. Since v and Xi are FEM functions in different FEM spaces, would you please tell me how to implement this formula in code? Thank you so much!