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Unformatted text preview: Complexity of direct methods n 1/2 n 1/3 2D 3D Space (fill): O(n log n) O(n 4/3 ) Time (flops): O(n 3/2 ) O(n 2 ) Time and space to solve any problem on any wellshaped finite element mesh Multigrid Multigrid (introduction) (introduction) • Find an approximate solution on a coarser mesh, and then improve it on a finer mesh • Reduce smooth finemesh error by using coarse mesh again • Use idea recursively on hierarchy of meshes • Solves the model problem (Poisson’s eqn) in linear time! • Often useful when hierarchy of meshes can be built • This is just the intuition – lots of theory and technology...
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This note was uploaded on 12/27/2011 for the course CMPSC 290h taught by Professor Chong during the Fall '09 term at UCSB.
 Fall '09
 Chong

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