Hello, Libmesh Users,
I have a question about the structure of the result vector of libmesh system.
The following codes are from  the GMVIO class :
00377           out << (*solution_names)[c] << 
" 1\n";
00379 for (unsigned int n=0; n<mesh.n_nodes(); n++)
00380 out << std::setprecision(10) << (*v)[n*n_vars + c] << " ";
00382 out << "\n\n";
00384 #endif

My question is : If the field variables of system don't use the equal order shape function, such as Q84 for stokes flow.

the four corner nodes have three variables : U, V, P. other four nodes on the middle of line have two variables: U, V.

c is 0 for U, c is 1 for V, c is 2 for P. n_vars is 3. When n is not the coner node, it only has two variable.

(*v)[n*n_vars+0] is U ,
(*v)[n*n_vars+1] is V. I want to know what is (*v)[n*n_vars+2] for this node?

Best regards,

Yours sincerely
Department of Engineering Mechanics
State Key Laboratory of Structural Analysis for Industrial Equipment
Dalian University of Technology
Dalian, 116023, P. R. China