RZRM: Research
Interior Point Methods for Linear Programming and Concave Quadratic Programming
Funding: CONACyT, México (Grant for graduate studies)
U. of Texas - Austin (Continuing Fellowship)
Dates: 1992 - 1994
People: Prof. Jon Bard (U. of Texas)
Supervisor

Roger Z. Ríos (U. of Texas)
Graduate Research Assistant

Summary: Before beginning my dissertation, I was involved in a research project to develop efficient interior point algorithms for linear programming. In this research, I developed and coded (in FORTRAN) a primal-dual interior point algorithm for linear optimization models. The aim was to solve large-scale instances. This code uses an efficient data structure for sparse matrix manipulation that greatly simplifies the computational load. As part of the research, I investigated and compared several of the existing state-of-the-art interior point method codes such as LOQO (developed by Prof. Robert Vanderbei from Princeton U.), HOPDM (developed by Prof. Anna Altman and Prof. Jacek Gondzio from Polish Academy of Sciences), and OSL (Optimization Subroutine Library from IBM). Although there was not an unanimous dominance, I found LOQO better structured and suitable for the second part of my research, which focused on using these interior point techniques to solve nonconvex quadratic optimization models. My approaches to this very difficult problem were not fully successful. After I developed an interior point algorithm for this problem, I faced several difficulties such as a slow rate of convergence and inability to efficiently escape from local optimum. As of today, nonconvex quadratic optimization remains one of the most challenging problems.

Publications:
Unpublished
[1] R. Z. Ríos Mercado. A primal-dual interior point algorithm. Working paper, Operations Research Group, U. of Texas, Austin, May 1992.
[2] R. Z. Ríos Mercado. Computational experience with a primal-dual interior point method for linear programming. Working paper, Operations Research Group, U. of Texas, Austin, November 1992.
[3] R. Z. Ríos Mercado. An algorithm for concave quadratic programming. Working paper, Operations Research Group, U. of Texas, Austin, May 1994.