  We consider the 2+1 dimensional massive Thirring model with one flavor at
finite density. Two numerical methods, fermion bag approach and complex
Langevin dynamics, are used to calculate the chiral condensate and fermion
density of this model. The numerical results obtained by fermion bag approach
are compared with those obtained by complex Langevin dynamics. They are also
compared with those obtained under phase quenched approximation. We show that
in some range of fermion coupling strength and chemical potential the sign
problem in fermion bag approach is mild, while it becomes severe for the
complex Langevin dynamics.
