We remarked that key problem with iterative methods is that got detail (short wavelength) correct but that convergence was controlled by coarse (long wavelength) structure
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Then in simple methods one needs of order N2 iterations to get good results
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Ironically one goes to large N to get detail as if all you wanted was coarse structure, a smaller mesh would be fine
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Basic idea in multigrid is key in many areas of science
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Solve a problem at multiple scales
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We get coarse structure from small N and fine detail from large N
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Good qualitative idea but how do we implement?
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Material taken from http://www.mgnet.org/mgnet/www/mgnet/www/mgnet/www/mgnet/www/ Tutorial by Ulrich Ruede
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