PETSc only supports the ODE solver (CVODE) from Sundials. Shri
From: Gautam Bisht <[email protected]<mailto:[email protected]>> Date: Mon, 3 Nov 2014 22:56:58 -0800 To: <[email protected]<mailto:[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.
