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