Combinatorica`ShowGraph HeadCenter option

*To*: mathgroup at smc.vnet.net*Subject*: [mg87107] Combinatorica`ShowGraph HeadCenter option*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Tue, 1 Apr 2008 03:20:33 -0500 (EST)*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst*Reply-to*: murray at math.umass.edu

In whatever version of Mathematica was current 5 years ago, the following code displayed a directed graph with the arrows located half-way along each edge: <<DiscreteMath`Combinatorica` g = SetGraphOptions[Cykcle[3], EdgeDirection -> True]; ShowGraph[g, HeadCenter -> 0.5] In Mathematica 6.0.2 (with Combinatorica` instead of DiscreteMath`Combinatorica`, of course), the option HeadCenter seems to be unrecognized, and the arrows remain at their target ends -- in other words, they appear where they are hardest to see! Has this change been documented? There is nothing whatsoever about this in Compatibility/tutorial/DiscreteMath/Combinatorica. Except that this compatibility guide states, "All of the functionality in DiscreteMath`Combinatorica` is available in the newly created Combinatorica Package." Plainly that is not the case in so far as HeadCenter is concerned. How can one still locate the arrows on the displayed directed graph -- using ShowGraph (which has been generally much simpler to use, especially for students, in contrast with the newer GraphPlot. -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305