Computation and presentation of graphs displaying closure hierarchies of Jordan and Kronecker structures

StratiGraph, a Java-based tool for computation and presentation of closure hierarchies of Jordan and Kronecker structures is presented. The tool is ba sed on recent theoretical results on stratifications of orbits and bundles of matrices and matrix pencils. A stratification reveals the complete hiera rchy of nearby structures. information critical for explaining the qualitat ive behaviour of linear systems under perturbations. StratiGraph facilitate s the application of these theories and visualizes the resulting hierarchy as a graph. Nodes in the graph represent orbits or bundles of matrices or m atrix pencils. Edges represent covering relations in the closure hierarchy. Given a Jordan or Kronecker structure, a user can obtain the complete info rmation of nearby structures simply by mouse clicks on nodes of interest. T his contribution gives an overview of the StratiGraph tool, presents its ma in functionalities and other features, and illustrates its use by sample ap plications. Copyright (C) 2001 John Wiley & Sons, Ltd.