Hi all, I am very new to the finite element field, and I want to try to solve the a variant of the fokker-plank equation with periodic boundary conditions. To do this, I need to find a way to impose an actual concentration in the system. Since I have a Robin boundary condition (no flux) at the surf…

Maybe the documentation from FEniCS is cleaner? It solves exactly the same problem, so the variational formulations are the same. If you want to switch to 3D, switch mesh to mesh3 and int2d to int3d.

That does help a bit thank you. It seems like the section matrix A = va(Vh, Vh); real[int] b = vL(0, Vh); real[int] B = vb(0, Vh); // Block matrix matrix AA = [ [ A, B ], [ B', 0 ] ]; set(AA, solver=sparsesolver); real[int] bb(n+1), xx(n+1), b1(1), l(1); b1 = 0; // Builds the right hand side blo…

I don’t think you need to change that for your application. The formulation in FreeFEM is really similar to what you would do in MATLAB, by defining a block matrix and concatenating vertically vectors or extracting scalars.

Thank you for your help with this! After tinkering with it for a few days, I have another question if it isn’t too much of a bother. I am trying to figure out what these sections are doing. varf vL (uh, vh) = int2d(Th)(f*vh); varf vb (uh, vh) = int2d(Th)(1.*vh); I am under the impression here tha…

f is the source term, vb discretizes the constraint int(u) = b1.

So if there is no source term, I can get away with f = 0? Thank you!

How to use Lagrange Multipliers in FreeFEM

General Discussion

prj July 29, 2020, 6:02am 8

Why couldn’t you? Try it and you’ll see for yourself…

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How to use Lagrange Multipliers in FreeFEM

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