SEPPLOT

 

 Used by SEPDEMO10GZB5X to show the separators.

   sepplot(A,xy,lname,sname): plot a mesh, a matrix, a tree, a factor,

   highlighting the top-level separator.

       A:  the matrix

      xy: the xy coordinates of the mesh

   lname: the text of the name of the permutation (long)

   sname: the text of the name of the permutation (short)