Contents Volume 240 MOHSEN MAESUMI (Beaumont, Texas) An Efficient Lower Bound for the Generalized Spectral Radius of a Set of Matrices THOMAS HOFMEISTER AND HANNO LEFMANN (Dortmund, Germany) Computing Sparse Approximations Deterministically JiN-HsIEN WANG (Kaohsiung, Taiwan, Republic of China) Factorization of Matrices Into Quadratic Ones. III L. A. V. CARVALHO (Sao Carlos, Brazil) On Quadratic Liapunov Functionals for Linear Difference Equations ROGER A. Horn (Salt Lake City, Utah), CHI-Kwonc Li (Williamsburg, Virginia), AND DENNIS I. MERINO (Hammond, Louisiana) Distances Between the Graphs of Matrices J. D. Borna (Pretoria, South Africa) Factorizations of a Matrix Into Symmetric Matrices With Prescribed Nullities BAHMAN KALANTARI AND LEONID KHACHIYAN (New Brunswick, New Jersey) On the Complexity of Nonnegative-Matrix Scaling CHARLES R. JOHNSON (Williamsburg, Virginia) AND FUZHEN ZHANG (Santa Barbara, California) An Operator Inequality and Matrix Normality M. ARIOLI (Pavia, Italy), B. CODENOTTI (Pisa, Italy), and C. Fassino (Roma, Italy) The Padé Method for Computing the Matrix Exponential MARKUS OLSCHOWKA (Freiburg, Germany) and ARNOLD NEUMAIER (Wien, Austria) A New Pivoting Strategy for Gaussian Elimination ANTON A. STOORVOGEL (Eindhoven, The Netherlands) Stabilizing Solutions of the Hee Algebraic Riccati Equation B. L. CHALMERS (Riverside, California), AND B. SHEKHTMAN (Tampa, Florida) Extension Constants of Unconditional Two-Dimensional Operators A. M. COHEN (Cardiff, United Kingdom) An Algebraic Approach to Certain Differential Eigenvalue Problems HONGYUAN ZHA (University Park, Pennsylvania) A Note on the Existence of the Hyperbolic Singular Value Decomposition Table of Contents continued PETER M. GIBSON (Huntsville, Alabama) Sing-Nonsingular Skew-Symmetric Matrices ZDENEK STRAKOS (Prague, Czech Republic) Review of Iterative Solution Methods, by O. Axelsson RICHARD BRUALDI (Madison; Wisconsin) From the Editor-in-Chief REFEREES, VOLUMES 221-240 AUTHOR INDEX, VOLUMES 221-240