u_operator        476 old_code/tumor_growth/tumor_code.h   const Tumor_Brusselator_operator u_operator {u_model, u_approx, w_approx};
u_operator        478 old_code/tumor_growth/tumor_code.h   LinearInverseOperatorType u_solver {u_operator, solverEps, solverEps};
u_operator        539 old_code/tumor_growth/tumor_code.h     u_operator.generate_rhs_old_surface(u_n, u_cg_rhs);
u_operator        546 old_code/tumor_growth/tumor_code.h     u_operator.generate_rhs_new_surface(tmp_fef);