[Libmesh-users] output evaluation with the 2D Poisson problem (introduction_ex3)

[Kyunghoon L. <aer...@gm...>]

Dear all,

I'd like to evaluate outputs after solving the 2D Poisson example; for
instance, the sum of u over the entire domain, \in_{\Omega} u d\Omega, and
the sum of u over specific boundaries, \in_{\Gamma} u d\Gamma.  I guess I
need to put some codes for output evaluations after

equation_systems.get_system("Poisson").solve();

, but I'm not sure of what to do --- do I need to create some assembly
functions for output evaluations then attach to the system?  I'd appreciate
it if someone could show necessary steps briefly.

Best regards,
K. Lee.