xi                107 old_code/2015linfty/dune_heat_algorithm.hpp   DiscreteFunctionType xi("xi", dfSpace);	// For the lineary implicit BDF method
xi                149 old_code/2015linfty/dune_heat_algorithm.hpp   NonlinearOperator ellipticOp {xi, model, bdf_alpha_coeff.back()};
xi                106 old_code/tumor_growth/tumor_code.h   DiscreteFunctionType xi("xi", dfSpace);	// For the lineary implicit BDF method
xi                148 old_code/tumor_growth/tumor_code.h   NonlinearOperator ellipticOp {xi, model, bdf_alpha_coeff.back()};