Hi David, Thank you for your fast answer. Indeed, I was not aware that in systems_of_equations_ex5 Lagrange multipliers are used as well; but it is only one DOF there as well, isn't? The problem in my case is that I don't know before, how many DOFs refer to the L (see matrix block sturcture) and how many to the actual problem described by H. But maybe I need to write a function that separates the parts on my own. Best, Tobias
________________________________ Von: David Knezevic [david.kneze...@akselos.com] Gesendet: Mittwoch, 11. Oktober 2017 13:03 An: Tobias Möhle Cc: libmesh-users@lists.sourceforge.net Betreff: Re: [Libmesh-users] Lagrange factors On Wed, Oct 11, 2017 at 5:02 AM, Tobias Möhle <tobias.moe...@uni-rostock.de<mailto:tobias.moe...@uni-rostock.de>> wrote: Dear all, I am trying to extend my current code to add Lagrange multipliers, leading to extra terms that couplet certain DOFs in a fixed range of the grid. To do so, I added another variable to my system, leading to the system-matrix of block-structure: / H L^T \ \ L 0 / where H is the matrix corresponding to the actual problem and L contains the Lagrange constrains. Thus, my system.solution contains in the first part the coefficients of the particular solution and in the lower part the Lagrange multipliers themselves. Now my question: is there some function to extract the Lagrange multipliers and the actual solution vector (dof-based) separately? Or how is it supposed to be done? I suggest you refer to systems_of_equations_ex5, since that uses a Lagrange multiplier to impose a constraint. Hopefully that answers your question. David ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
