Dear Nicolo Cambiaso,
You can use gf_asm to produce a mass matrix as you tried, but you have to specify a fem on which the variable is described. The correct syntax is for instance gf_asm('generic', mim3, 2, 'Grad_Test2_ut.Grad_Test_ut', -1, 'ut',1, mf, zero(gf_mesh_fem_get(mf, 'nbdof'),1)); where mf is the mesh_fem structure describing the fem. Best regards, Y.R. ----- Mail original ----- De: "Nicolò Cambiaso" <cambiaso.nic...@gmail.com> À: "getfem-users" <getfem-users@nongnu.org> Envoyé: Lundi 30 Septembre 2019 12:25:51 Objet: [Getfem-users] Generic Bricks definition using gf_asm. Dear users, I would like to solve a system of equations using Getfemm++ with Matlab interface. So I created a block matrix, and now i cannot create the corresponding bricks. I'm using the command "gf_asm", hoping it's the correct one. the block is the following: Mtt=1/k u_t v_t. (v_t is the test function corresponding to u_t) in full despair, i also removed the 1/k therm, and still nothing worked. this is what i wrote: gf_asm('generic', mim3, 2, 'Grad_Test2_ut.Grad_Test_ut', -1, 'ut',1, U); And the error message is: "Error using gf_matlab Error in getfem_generic_assembly.cc, line 9519 void getfem::ga_node_analysis(const string&, getfem::ga_tree&, const getfem::ga_workspace&, getfem::pga_tree_node, bgeot::size_type, bgeot::size_type, bool, bool, int): Error in assembly string Error in gf_asm (line 338) [varargout{1:nargout}]=gf_matlab('asm', varargin{:}); Error in Comeon (line 56) Mtt=gf_asm('generic', mim3, 2, 'Grad_Test2_ut.Grad_Test_ut', -1, 'ut',1, U); % M_tt, proviamo" with mim3= gf_mesh_im( mf3, gf_integ('IM_NC(3,1)') ) mf3=gf_mesh_fem(OmegaM,3) OmegaM=gf_mesh('regular simplices',vectX, vectY, vectZ, 'degree', 1) at his point, i defined U as ones(2,2,2,3), having the vectX(/Y/Z) only 2 points each one, for now, and because u_t is a 3D vector. I think that's not correct, but i have no idea of the correct dimension of U, and i tried everything that came to my mind ... and still nothing worked. I found a lot of material dealing with this on c++ interface, but unfortunately I cannot male it work in Matlab. thank you very much, Nicolo Cambiaso.