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<div>PETSc only supports the ODE solver (CVODE) from Sundials. </div>
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<div>Shri</div>
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<span style="font-weight:bold">From: </span>Gautam Bisht <<a href="mailto:gbisht@lbl.gov">gbisht@lbl.gov</a>><br>
<span style="font-weight:bold">Date: </span>Mon, 3 Nov 2014 22:56:58 -0800<br>
<span style="font-weight:bold">To: </span><<a href="mailto:petsc-users@mcs.anl.gov">petsc-users@mcs.anl.gov</a>><br>
<span style="font-weight:bold">Subject: </span>[petsc-users] sundials results do not agree with beuler/rosw/pseudo<br>
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<div dir="ltr">Hi,
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<div>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.</div>
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<div>I'm using following PETSc options:</div>
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<div>>/opt/local/bin/mpiexec -n 1 $EXEROOT/cesm.exe \<br>
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<div>-ts_monitor \</div>
<div>-ts_view \</div>
<div>-snes_monitor \</div>
<div>-pc_type lu \</div>
<div>-ts_type sundials -ts_sundials_monitor_steps \</div>
<div>-ts_dt 1.0 -ts_final_time 1.0</div>
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<div>0 TS dt 1 time 0</div>
<div>1 TS dt 1 time 1</div>
<div>TS Object: 1 MPI processes</div>
<div> type: sundials</div>
<div> maximum steps=100000</div>
<div> maximum time=1</div>
<div> total number of nonlinear solver iterations=0</div>
<div> total number of nonlinear solve failures=0</div>
<div> total number of linear solver iterations=0</div>
<div> total number of rejected steps=0</div>
<div> Sundials integrater does not use SNES!</div>
<div> Sundials integrater type BDF: backward differentiation formula</div>
<div> Sundials abs tol 1e-06 rel tol 1e-06</div>
<div> Sundials linear solver tolerance factor 0.05</div>
<div> Sundials max dimension of Krylov subspace 5</div>
<div> Sundials using unmodified (classical) Gram-Schmidt for orthogonalization in GMRES</div>
<div> Sundials suggested factor for tolerance scaling 1</div>
<div> Sundials cumulative number of internal steps 1</div>
<div> Sundials no. of calls to rhs function 2</div>
<div> Sundials no. of calls to linear solver setup function 1</div>
<div> Sundials no. of error test failures 0</div>
<div> Sundials no. of nonlinear solver iterations 1</div>
<div> Sundials no. of nonlinear convergence failure 0</div>
<div> Sundials no. of linear iterations 0</div>
<div> Sundials no. of linear convergence failures 0</div>
<div> PC Object: 1 MPI processes</div>
<div> type: lu</div>
<div> PC has not been set up so information may be incomplete</div>
<div> LU: out-of-place factorization</div>
<div> tolerance for zero pivot 2.22045e-14</div>
<div> matrix ordering: nd</div>
<div> linear system matrix = precond matrix:</div>
<div> Mat Object: 1 MPI processes</div>
<div> type: seqaij</div>
<div> rows=200, cols=200</div>
<div> total: nonzeros=598, allocated nonzeros=3200</div>
<div> total number of mallocs used during MatSetValues calls =200</div>
<div> not using I-node routines</div>
<div> Sundials no. of preconditioner evaluations 1</div>
<div> Sundials no. of preconditioner solves 0</div>
<div> Sundials no. of Jacobian-vector product evaluations 0</div>
<div> Sundials no. of rhs calls for finite diff. Jacobian-vector evals 0</div>
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<div>Thanks,</div>
<div>-Gautam.</div>
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