Re: Is this a bug in the Adjacency Matrix function? Using 8.9.4.0

*To*: mathgroup at smc.vnet.net*Subject*: [mg123994] Re: Is this a bug in the Adjacency Matrix function? Using 8.9.4.0*From*: Szabolcs <szhorvat at gmail.com>*Date*: Wed, 4 Jan 2012 05:04:11 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <jdulgc$jr3$1@smc.vnet.net>*Reply-to*: comp.soft-sys.math.mathematica at googlegroups.com

On Tuesday, 3 January 2012 11:32:44 UTC+1, Richard Palmer wrote: > testgraph=Graph[#[[1]]\[DirectedEdge]#[[2]]&/@{{1,3},{2,3},{3,4},{3,5},{4,6},{4,7},{5,7},{6,7}}, > VertexLabels->"Name", > ImagePadding->10] > > > MatrixForm[AdjacencyMatrix[testgraph], > TableHeadings -> {Range[7], Range[7]}] > > > The Adjacency Matrix appears to be incorrect, e.g. 1 is not adjacent to 2. > What am I missing? Writing an adjacency matrix assumes an ordering of vertices. In Mathematica this is not a simple lexicographic ordering, but the ordering is the same as that returned by VertexList. The correct code to show the adjacency matrix is MatrixForm[AdjacencyMatrix[testgraph], TableHeadings -> {VertexList[testgraph], VertexList[testgraph]}]