Dear All, 

I recently installed libMesh and I am trying things out; I am new to libMesh 
and also to FE methods, so I apologise if this is a rather basic question, but 
your help would be much appreciated. Based on the example codes provided, I 
have written a little program to solve a 1D eigenvalue problem which works 
fine. In my first implementation I used LAGRANGE finite elements, which I 
understand guarantee continuity of the (eigen)functions across elements, but 
not of their derivatives (C0 continuity). I also understand that in order to 
enforce continuity of the 1st derivative I should switch to finite elements 
based on Hermite interpolating polynomials, which I have done with the 
following lines of code:

MeshTools::Generation::build_line( mesh, npoints, -L0, L0, EDGE3 );
…
eigen_system.add_variable( "p", THIRD, HERMITE );

and if I am not mistaken, this will ensure that the eigenvectors have C1 
continuity (though please correct me if wrong). My question is: is it possible 
to enforce C2 continuity (continuity of function, first and second 
derivatives)? I naively assumed that this would be possible by using a higher 
order of HERMITE (e.g. FIFTH) in the appropriate line above, but this does not 
appear to work. 

Thanks in advance,

Eduardo

Eduardo R. Hernández
Instituto de Ciencia de Materiales de Madrid (ICMM)
Consejo Superior de Investigaciones Científicas
Campus de Cantoblanco
28049 Madrid

tel.: +34 91 3348994
email: [email protected]
http://www.icmm.csic.es/ehernandez/Site/Home.html



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