Shri: Thanks for pointing out that I need IDA instead of CVODE from sundials, which isn't currently supported by PETSc. Are there any near term plans for supporting IDA via PETSc?
Barry: I now realize that PSEUDO is applicable for steady-state problems. For the time being I will stick with BEULER and ROSW methods and look into PCFIELDSPLIT. -Gautam. On Tue, Nov 4, 2014 at 8:19 AM, Barry Smith <[email protected]> wrote: > > Note: PSEUDO is a continuation method for solving a nonlinear system, it > doesn’t make sense to use it to replace other methods. > > That time step of 1 seems very large for SUNDIALs to be using > > Barry > > > On Nov 4, 2014, at 9:40 AM, Abhyankar, Shrirang G. <[email protected]> > wrote: > > > > PETSc only supports the ODE solver (CVODE) from Sundials. > > > > Shri > > > > From: Gautam Bisht <[email protected]> > > Date: Mon, 3 Nov 2014 22:56:58 -0800 > > To: <[email protected]> > > Subject: [petsc-users] sundials results do not agree with > beuler/rosw/pseudo > > > > Hi, > > > > I'm solving subsurface flow equation in which the governing ODE is > reformulated as a system of DAE. I'm using PETSc TS+DMComposite to solve > the system with a LU preconditioner. I get comparable results for BEULER, > ROSW and PSEUDO ts_type. But results with SUNDIALS for even a single TS > step are significantly underestimated when compared to those obtained for > the other ts_types. I would appreciate if folks would suggest ideas on how > can I go about figuring out what is going wrong with SUNDIALS. > > > > I'm using following PETSc options: > > > > >/opt/local/bin/mpiexec -n 1 $EXEROOT/cesm.exe \ > > -ts_monitor \ > > -ts_view \ > > -snes_monitor \ > > -pc_type lu \ > > -ts_type sundials -ts_sundials_monitor_steps \ > > -ts_dt 1.0 -ts_final_time 1.0 > > > > 0 TS dt 1 time 0 > > 1 TS dt 1 time 1 > > TS Object: 1 MPI processes > > type: sundials > > maximum steps=100000 > > maximum time=1 > > total number of nonlinear solver iterations=0 > > total number of nonlinear solve failures=0 > > total number of linear solver iterations=0 > > total number of rejected steps=0 > > Sundials integrater does not use SNES! > > Sundials integrater type BDF: backward differentiation formula > > Sundials abs tol 1e-06 rel tol 1e-06 > > Sundials linear solver tolerance factor 0.05 > > Sundials max dimension of Krylov subspace 5 > > Sundials using unmodified (classical) Gram-Schmidt for > orthogonalization in GMRES > > Sundials suggested factor for tolerance scaling 1 > > Sundials cumulative number of internal steps 1 > > Sundials no. of calls to rhs function 2 > > Sundials no. of calls to linear solver setup function 1 > > Sundials no. of error test failures 0 > > Sundials no. of nonlinear solver iterations 1 > > Sundials no. of nonlinear convergence failure 0 > > Sundials no. of linear iterations 0 > > Sundials no. of linear convergence failures 0 > > PC Object: 1 MPI processes > > type: lu > > PC has not been set up so information may be incomplete > > LU: out-of-place factorization > > tolerance for zero pivot 2.22045e-14 > > matrix ordering: nd > > linear system matrix = precond matrix: > > Mat Object: 1 MPI processes > > type: seqaij > > rows=200, cols=200 > > total: nonzeros=598, allocated nonzeros=3200 > > total number of mallocs used during MatSetValues calls =200 > > not using I-node routines > > Sundials no. of preconditioner evaluations 1 > > Sundials no. of preconditioner solves 0 > > Sundials no. of Jacobian-vector product evaluations 0 > > Sundials no. of rhs calls for finite diff. Jacobian-vector evals 0 > > > > Thanks, > > -Gautam. > > > >
