On Fri, Jun 12, 2020 at 12:56 PM Qin Lu via petsc-users < petsc-users@mcs.anl.gov> wrote:
> Hello, > > I plan to solve a small sparse linear equation system using the direct > solver, since the number of unknowns is small (less than 1000). Here I got > a few questions: > > 1. Is there a general guide line on the size of the system that direct > solver is more efficient than iterative solver? > No. Direct solvers are about O(N^2) complexity and iteratives solvers can be O(N) - O(N^inf) > 2. Is the native Petsc direct solver (using KSPPREONLY and PCLU) designed > to solve dense system or sparse system? > sparse. > 3. Is the native Petsc direct solver comparable to SuperLU and MUMPS in > performance? Do they use different algorithms? > PETSc's is only in serial and CPU. MUMPS and SuperLU are MPI parallel. SuperLU runs on GPUs. SuperLU and MUMPS have more optimizations, such that there is probably a significant difference on some problems but it's hard to say in general. > > Thanks in advance for your help. > > Best Regards, > Qin >
