Restriction Basic Principles Given wn we obtain w2h by restriction 2h= Th 2h200 C2h: restriction operator(matrix) Simplest procedure is injection 021,2=,2fori=1,,n21 SMA-HPC⊙2003MT Iterative Methods: Multigrid Techniques 10
Restriction Basic Principles Intuitively 2h GOOD BAD SMA-HPC⊙2003MT Iterative Methods: Multigrid Techniques 11
Restriction Basic Principles If we write Uk: eigenvectors of A h Ck U Only the modes k =1, are "visible" by grid 2h 2 visible"by grid 2h aliased m-1m+1 2 SMA-HPC⊙2003MT Iterative Methods: Multigrid Techniques 12