Transient stability-constrained optimal power flow, G. Geng, Zhejiang Univ. comments on the TSOPF_RS_b2303 matrix: We are now trying UMFPACK in MATLAB to do some research work power system optimization. UMFPACK LU function (5 outputs) performs much faster than normal LU function (3 outputs) of MATLAB for most test cases in our experiment. However, in one of our test, UMFPACK runs out of memory when performing LU decomposition to an unsymmetric, non-positive definite matrix Ck (uploaded on the website). But the normal LU function with COLAMD successfully completes LU decomposition without any warning and error. All tests are done in MATLAB 2008b x64 on a PC with 4Gb RAM. We have tried both UMFPACK 5.0 and 5.2 but neither works. We would very appreciate it if you could give some suggestions on our implementation. comments from Guangchao Geng regarding the TSOPF_FS_300 matrix: KLU (which you recommend us in your last letter) does a perfect a job in our application of power system optimization. It's faster than UMFPACK and SuperLU about 10 times in LU factorization phase and 5 times in backward substitution phase. It greatly speeds up our research work. However, when we try UMFPACK and KLU to solve a symmetric sparse linear system in another program, both of the two fails to exceed backslash in MATLAB. The left-hand side matrix A and right-hand side vector b1 are uploaded in a single .MAT file at the website. We wonder if MATLAB backslash is the performance limit for matrices of this kind, or we have other external solvers worth to try. Thank you for your consideration. Guangchao Geng -------------- Guangchao Geng E-mail: genggc at gmail dot com Institute of Power System, College of Electrical Engineering, Zhejiang University, Hangzhou, 310027, China. remainder: Here is a matrix collection of our power system optimization application, This .zip file contains matrices collection of Transient Stability constrained Optimal Power Flow (TSOPF). All matrices are stored in MAT format and divided in two groups: Full-Space (FS) group and Reduced-Space (RS) group. FS group: - Left-hand side: A (symmetric & indefinite) - Right-hand side: b1 - Solve fastest with Matlab backslash '\' (actually MA57) RS group: - Left-hand side: Ck (asymmetric & indefinite) - Right-hand side: Nk (sparse with 300+ columns for large systems) - Solve fastest with KLU Guangchao Geng (genggc at gmail dot com) 2009.01.08 (Update: the titles of the matrices were corrected on March 6, 2009).