I though that I had understood the difference between interpolate and project. The first one looks for a function that whose values coincide at the points of the mesh whereas the second one looks for a function that minimizes some norm. I tried a very simple case: Lets say that I have a function de…

Ok, I think I more or less understand it. As I try to project function f onto the space of function h, first it interpolates f in order to compute the inner products, etc. So that’s why I get the same values for the interpolated and the projected one. If I want to obtain the correct values, I can d…

I would suggest using ufl.conditional with SpatialCoordinate to create something that is evaluated at quadrature points, see for instance: Unable to use conditional module - #2 by dokken

I understand that that would be the solution to correctly interpolate an expression onto a given functional space. My question is. Assuming that I have a fem function, defined on some functional space. How can I get project to use the cuadrature points? I don’t know if I’m explaining my self. How …

Summarizing: mesh_1 = IntervalMesh(2,0.,1.) mesh_2 = IntervalMesh(1,0.,1) H_1 = FunctionSpace( mesh_1, FiniteElement( family="Lagrange", cell= mesh_1.ufl_cell(), degree=1)) H_2 = FunctionSpace( mesh_2, FiniteElement( family="Lagrange", cell= mesh_2.ufl_cell(), degree=1)) f = Function(H_1) g = Funct…

I would suggest changing the quadrature order of the projection, as you are trying to project a function of higher regularity (f) onto a space of lower regularity (g).

Thanks, I think that is what I need. I don’t know however how to do it. I’ve tried: h = project(f,V=H_2, form_compiler_parameters = {"quadrature_degree", 2}) which gives me an error: ValueError: dictionary update sequence element #0 has length 17; 2 is required Which is the correct syntax? is t…

Thank you very much, that explains it

Problems understanding project function

mathematics

dokken July 15, 2022, 6:23am 8

You would need to write out the projection operator by hand, see for instance: Projection of user expression onto DG1 - #4 by kamensky

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Problems understanding project function

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