From: yunfei zhu <yzhu2009@go...>  20110114 16:03:41

Dear all, I am working on tracing the equilibrium path of the unstable static nonlinear problem. So, the arclength method are needed. Another scalar parameter \lambda is added to the original equation systems by: system.add_variable("lambda",FIRST,SCALAR); and then solve the augmented system. First, I use element: tet4. It works for small pressure. but when I use mesh.all_second_order() to convert the mesh from tet4 to tet10, I get warning like this: WARNING: Second derivatives are not currently correctly calculated on nonaffine elements! I noted that this warning come from function FEBase::compute_map() in fe_map.C file. 00497 #ifdef LIBMESH_ENABLE_SECOND_DERIVATIVES00498 if (calculate_d2phi <http://libmesh.sourceforge.net/doxygen/classlibMesh_1_1FEBase.php#a4170551fa0860822e21475e3c098bc13>)00499 {00500 libmesh_do_once(00501 libMesh::err <http://libmesh.sourceforge.net/doxygen/namespacelibMesh.php#ab0817b8542b150bfa3fb23393df99f28>; << "WARNING: Second derivatives are not currently "00502 << "correctly calculated on nonaffine elements!"00503 << std::endl;);00504 }00505 #endif I don't need to calculate the second derivatives for my problem and I did not enable the second derivatives when I installed libmesh. But why I get this warning. By the way, I am trying to using ContinuationSystem to tackle my problem also. I am not totally sure how to use ContinuationSystem until now, but I run some experimental code anyway. This code give the warning above also. I am confused why this happen. could anyone help me? thank you very much. Best wishes, yunfei 