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. >
