Umut Tabak <[email protected]> a écrit : > Dear Professor Renard, > > First, of all, I would like let you know, that I am registered for > the Getfem users mailing list, but none of my posts appear on the > mailing list pages on the gna server. I confirmed my membership but > as said, my messages do not appear online. Do you have any idea what > I should do.
This is probably because you use a different mail address than the one you give to register yourself. > > I have 1 question and possibly one inconsistency in the matrix > market export of the matrices that are formed by the getFem++. > > 1.) I am trying to use the library for my Ph.D. research project in > order to assemble my system matrices (For the moment I am concerned > with interior vibroacoustic problems so I need the assemble the > structural and fluid parts of the matrices as well as the coupling > terms which result in an unsymmetric system, most probably, you are > familiar with this problem). I followed the documentation and could > assemble some matrices for the solution of the helmholtz equation on > a, say, 3d domain where I import the mesh from Gmsh. This type of > problem is a scalar problem since only the pressures are the > unknowns. I set the dimension of the mesh to 1 with the set_qdim() > method and use FEM_QK(3,1) without problems, though the mesh is 3D > but with set_qdim(1) I can get the right results which I could nor > understand. > > If I try to use the linear elasticity assemble function on page 27 > on the manual, namely, asm_stiffness_matrix_for_linear_elasticity, > with mesh dimension 1, I get a wrong qdim error for the mesh_fem, if > I use set_qdim(3) and for instance with FEM_PK(3,1) and > IM_TETRAHEDRON(5) I get > > Error in /usr/local/include/getfem/getfem_assembling.h, line 577 : > invalid data mesh fem (Qdim=1 required) This means that you give the elasticity coefficients on a vectorial fem. You need two fems to call this assembly procedure a first one for the unknown which as to be vectorial (set_qdim(N)) and a second one, which is often a P0 method if your coefficients are constant, to describe the Lamé coefficients. Note that in the current devloppement version (you can get via gna.org) there is an assembly procedure, namely asm_stiffness_matrix_for_homogeneous_linear_elasticity which does not require a fem for the lamé coefficient. > > Elasticity problem is a vectorial problem, is not the dimension 3? I > could not understand where I making a mistake I guess I have > conceptual misunderstanding at some point. Could you help me on this > problem? > > 2.) I am not sure if this is a bug or not. When I form my matrices > for the scalar problem explained above. I export them in the matrix > market format using the gmm++ functions, but sometimes in the > export, if the matrix dimension are high, say 13690, I get 'nan' > entries in the exported matrix. I tried the hb export format, and it > seems to work correctly for the same problem, I do not get any 'nan' > entries in the matrices exported. If you like I can send you these > files for your further experimentation. Yes please, and if possible the smallest program producing these files. Regards, Yves. > > With the kindest regards, > > Umut > > > _______________________________________________ Getfem-users mailing list [email protected] https://mail.gna.org/listinfo/getfem-users
