Hi, I apologize for the slepc question. I could not find any user lists so I'm hoping someone on here might be able to offer some guidance.
*Problem Definition:* I am working on a graph partitioning problem. I have the laplacian of a large graph(500,000 nodes) and am interested in extracting its global information in order to find good partitioning. An approach is to compute the first few(4-5) eigenvalues and use that information to formulate the partition algorithm. I am leveraging the EPS solvers of the Slepc library. It appears that the Jacobi-davidson eigen solver gives me the eigenvalues in the shortest period of time compared to others (Krylov-Schur, Rayleigh quotient, Lanczos, etc). I use this eigensolver with the conjugate gradient linear solver and the block-jacobi preconditioner. So this is what I am basically passing through the command line: ./RunPart -eps_type jd -eps_nev 4 -st_ksp_type cg -st_ksp_rtol 0.001 -eps_tol 0.001 -st_pc_type bjacobi -eps_smallest_real *Question:* The time it takes to compute the first 4-5 eigenvectors of a matrix of size (200k) is near about 60 seconds. CPU config: Intel Xeon 2GHz. I am using a single processor to run my code. Is there any way I can gain major speedup than what I am getting? Is it possible to obtain the eigenvalues inside 10-15 seconds of such huge matrices even if I do not use multiple processor?? Can someone provide me with some valuable guidance?? *Thanks,* Bodhi
