A Geometric Analysis of Renegar's Condition Number, and its Interplay with Conic Curvature

For a conic linear system of the form Ax K, K a convex cone, several condition measures have been extensively studied in the last dozen years. Among these, Renegar’s condition number C(A) is arguably the most prominent for its relation to data perturbation, error bounds, problem geometry, and computational complexity of algorithms. Nonetheless, C(A) is a representation-dependent measure which is usually difficult to interpret and may lead to overly-conservative bounds of computational complexity and/or geometric quantities associated with the set of feasible solutions.

Herein we show that Renegar’s condition number is bounded from above and below by certain purely geometric quantities associated with A and K, and highlights the role of the singular values of A and their relationship with the condition number. Moreover, by using the notion of conic curvature, we show how Renegar’s condition number can be used to provide both lower and upper bounds on the width of the set of feasible solutions. This complements the literature where only lower bounds have heretofore been developed.

By: Alexandre Belloni; Robert M. Freund

Published in: RC24236 in 2007


This Research Report is available. This report has been submitted for publication outside of IBM and will probably be copyrighted if accepted for publication. It has been issued as a Research Report for early dissemination of its contents. In view of the transfer of copyright to the outside publisher, its distribution outside of IBM prior to publication should be limited to peer communications and specific requests. After outside publication, requests should be filled only by reprints or legally obtained copies of the article (e.g., payment of royalties). I have read and understand this notice and am a member of the scientific community outside or inside of IBM seeking a single copy only.


Questions about this service can be mailed to reports@us.ibm.com .