Implementation of the multigrid algorithms for nonconforming finite element methods using a newintergrid transfer operator

In this paper we present a new intergrid transfer operator in multigrid algorithms for P1-nonconforming finite element method for second order elliptic problems. Using this operator, the nonconforming multigrid methods need less computational work than standard intergrid transfer operator and sometimes the convergence rate (Delta)k decreases in comparison with standard intergrid transfer operators.