Department of Computer Science and Technology, Tsinghua University, Beijing 100084, P.R. China;
Department of Computer Science and Technology, Tsinghua University, Beijing 100084, P.R. China;
Department of Computer Science and Technology, Tsinghua University, Beijing 100084, P.R. China;
Department of Computer Science and Technology, Tsinghua University, Beijing 100084, P.R. China;
quadratic placement; Lagrange multiplier; incremental LU factorization;