44 lines
1.8 KiB
Mathematica
44 lines
1.8 KiB
Mathematica
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%
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% On a Matrix and Its Graph
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%
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% At the 1993 Householder Symposium on Numerical Algebra in Lake Arrowhead,
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% Nick Trefethen posted a flip chart and invited everyone present to write
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% their name on it, and to draw lines connecting their name with the names
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% of all their coauthors. The diagram grew denser throughout the week; at
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% the end it was a graph with 104 vertices (or people) and 211 edges.
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%
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% A graph is a sparse matrix, so just for fun we typed the graph into Matlab
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% and looked at it in a few different ways. You can say "runme" to Matlab
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% to see the results.
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%
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% The original flip chart is now framed on the wall of Nick's office at
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% Cornell. He promises to bring it along to Householder 2023.
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%
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% - John Gilbert, Cleve Moler, Nick Trefethen
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% with thanks to Rob Schreiber, Barry Smith, and 99 others.
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%
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% ----------------------------------------------------------------------
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% List of files in matlab/householder:
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%
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% README.m This file.
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%
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% runme.m Matlab script to show off the matrix and the graph.
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%
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% drawit.m Matlab script just to draw the graph.
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%
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% graph.ps Black-and-white postscript picture of the graph.
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%
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% housegraph.mat The raw data, as follows:
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%
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% A is the 104x104 adjacency matrix of the graph.
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% xy is the array of vertex coordinates for the picture.
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% name is a character matrix with 104 rows, each row giving the
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% name of the person associated with a vertex.
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% Every person's name is also a scalar variable whose value is
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% that person's vertex number; for example,
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% Stewart = 77 and name(77,:) = 'Stewart'.
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% prcm is a permutation (based on reverse Cuthill-McKee)
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% to reorder the graph for the picture.
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help README
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