## Luis F. Portugal## 1964.03.30 ~ 1998.07.21 |

Luis Portugal died on July 21, 1998 in Lisbon, Portugal, at the young age of 34. The cause was complications following a bone marrow transplant. Luis had been fighting a lymphoma for the past three and a half years. Funeral services were held in Coimbra following the international meeting "Optimization 98" held there on July 20-22.

Luis was intensely dedicated to his work, family, and friends, as well as about the way he lived. He leaves, unfinished, his Ph.D. dissertation (under the supervision of J. J. Júdice), his wife Helena (Lena), and many, many friends. They all miss him very much.

Throughout his short career, Luis made several important contributions to his field of investigation. His research interests were concentrated in linear and quadratic programming, network optimization, interior-point methods, and iterative methods for linear systems. His great ideas and his enthusiasm about research are greatly missed. Here is his bibliography:

L. Portugal, A. Portugal and J. Júdice, "Estimaçăo de parâmetros cinéticos de um sistema reaccional utilizado na preparaçăo de resinas de melamina formaldeido em meio butanólico," in M. Turkman and M. Carvalho (Eds.), Proceedings of the First Portuguese Conference on Statistics and Optimization, Troia, pp. 557-593, 1990.

L. Portugal, J. Júdice, and L. Vicente, "A comparison of block pivoting and interior-point algorithms for linear least-squares problems with nonnegative variables," Mathematics of Computation, vol. 63, pp. 625-643, 1994.

L. Portugal, "On the solution of least square problems," Master Thesis, University of Coimbra, 1992 (written in Portuguese).

L. Portugal, F. Bastos, J. Júdice, J. Paixăo, and T. Terlaky, "An investigation of interior-point algorithms for the linear transportation problem," SIAM Journal on Scientific Computing, vol. 17, pp. 1202-1223, 1996.

L. Portugal and J. Júdice, "A hybrid algorithm for the solution of a large-scale single commodity equilibrium model," Computers and Operations Research, vol. 23, pp. 623-639, 1996.

L. Portugal, M. Resende, G. Veiga and J. Júdice, "A truncated primal-infeasible dual-feasible network interior-point method," Networks, vol. 35, pp. 91-108, 2000.

L. Portugal, L. Fernandes and J. Júdice, "A truncated Newton interior-point algorithm for the solution of a multicommodity spatial equilibrium problem," in M. Ferris and J. Pang, (Eds.), Complementarity and Variational Problems, SIAM, pp. 415-444, 1997.

J. Júdice L. Portugal, M. Resende and G. Veiga, "A truncated Newton interior point method for the solution of the multicommodity minimum cost network flow problem," Proceedings of the First Portuguese Conference on Telecommunications, Aveiro, Portugal, pp. 381-384, 1997 (written in Portuguese).

J. Júdice, J. Patrício, L. Portugal, M. Resende, and G. Veiga, "A study of preconditioners for network interior point methods," Computational Optimization and Applications, vol. 24, pp. 5-35, 2003.

J. Patrício, L. Portugal, M. Resende, G. Veiga, and J. Júdice, "Fortran subroutines for network flow optimization using an interior point algorithm," Pesquisa Operacional, vol. 28, pp. 243-261, 2008.