Stephen A. Vavasis
Associate Professor
vavasis@cs.cornell.edu
http://www.cs.cornell.edu/home/vavasis/vavasis.html
PhD Stanford, 1989
As computer hardware becomes more powerful, there is
a corresponding growth in the demand for more efficient
algorithms to solve largescale scientific problems. My
research is on the design and analysis of such algorithms.
Ph.D. student V. Howle and I are developing algorithms
for modeling and simulation of AC electric power
networks. Utility companies are interested in modeling
the behavior of the network in the presence of a fault 

(closed circuit breaker). The governing equations, called
the "swing equations", are differential algebraic equations for the rotor angles of the generators in the system. We
are developing new, more accurate algorithms for the
swing equations and for linear subproblems.
Work on geometry in scientific computing continues.
Ph.D. student G. Jonsson and I are studying the problem
of robust intersection of parametric patches with rays
and planes. This problem arises in geometric modeling
and mesh generation. We are building on recent
previous work that transforms the problem to an
eigenvalue computation to improve accuracy. Accuracy
is paramount in this setting because a single failure of a
pointinmodel computation could cause an entire
numerical simulation to fail. We are also continuing work on QMG mesh
generation software
(based on an algorithm developed jointly with S. Mitchell of Sandia). The
forthcoming version of QMG will
robustly handle very general domains
with boundaries defined by curved
Bezier patches. The QMG project is
part of a grandchallenge project on
computational fracture mechanics
involving colleagues in CS, Civil
Engineering, and other schools.
University Activities

Acting Director: Center for
Applied Mathematics

Faculty Senate
Professional Activities

Editor: Journal Global
Optimization, SIAM Journal
Matrix Analysis Appl., SIAM
Review

Book reviewer: SIAM Review

Referee: Math. Progr.,
Math. Comp., SIAM Journal
Sci.
Comp., Oper. Res. Letters,
Journal Complexity, Journal
Egyptian Math. Soc., Proc.
Found. Comp. Sci., SIAM
Journal Matrix An. App. Lectures

Weighted leastsquares
parameters for graphs. Invited
presentation. Conference on
Approximation and Complexity
in Optimization, Univ. of
Florida, March 1, 1999.
 Solving polynomial systems
using eigen
values. Sixth SIAM
Optimization Conference,
Atlanta, GA, May 12, 1999.
 —. Numerical Analysis
Colloquium, Stanford Univ.,
May 18, 1999.
 —. Numerical Analysis
Colloquium, Bell Labs, Murray
Hill, NJ, June 3, 1999.
 Support trees for structural
analysis. Plenary talk.
Householder Conference on
Numerical Linear Algebra,
Whistler, BC, June 16, 1999.
Publication

Numerical conformal mapping using
crossratios and Delaunay
triangulation, SIAM Journal
Sci.
Comp. 19 (1998), 17831803 (with
T. Driscoll).
