<div dir="ltr"><br><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, May 8, 2013 at 4:41 PM, Jed Brown <span dir="ltr"><<a href="mailto:jedbrown@mcs.anl.gov" target="_blank">jedbrown@mcs.anl.gov</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="im">Lulu Liu <<a href="mailto:lulu.liu@kaust.edu.sa">lulu.liu@kaust.edu.sa</a>> writes:<br>
<br>
> I want to register a new adaptive time-step scheme for the backward Euler<br>
> method. I used options:<br>
><br>
> -ts_adapt_type myscheme -ts_theta_adapt<br>
><br>
> The error message is show as:<br>
><br>
> No time-step adaptivity implemented for 1st order theta method;<br>
<br>
</div>Please show the full error trace. </blockquote><div><br></div><div><div>[0]PETSC ERROR: --------------------- Error Message ------------------------------------</div><div>[0]PETSC ERROR: !</div><div>[0]PETSC ERROR: No time-step adaptivity implemented for 1st order theta method; Run with -ts_adapt_type none!</div>
<div>[0]PETSC ERROR: ------------------------------------------------------------------------</div><div>[0]PETSC ERROR: Petsc Development GIT revision: 74fa8af516e4ffa7baa85f37320beb10b82d3143 GIT Date: 2013-05-07 22:57:41 -0500</div>
<div>[0]PETSC ERROR: See docs/changes/index.html for recent updates.</div><div>[0]PETSC ERROR: See docs/faq.html for hints about trouble shooting.</div><div>[0]PETSC ERROR: See docs/index.html for manual pages.</div><div>
[0]PETSC ERROR: ------------------------------------------------------------------------</div><div>[0]PETSC ERROR: ./case1 on a arch-basic named kl-12681.local by liul Wed May 8 16:48:31 2013</div><div>[0]PETSC ERROR: Libraries linked from /Users/liul/soft/petsc/arch-basic/lib</div>
<div>[0]PETSC ERROR: Configure run at Wed May 8 10:11:46 2013</div><div>[0]PETSC ERROR: Configure options --download-f-blas-lapack --download-mpich --with-cc=gcc --with-fc=gfortran PETSC_ARCH=arch-basic</div><div>[0]PETSC ERROR: ------------------------------------------------------------------------</div>
<div>[0]PETSC ERROR: TSEvaluateStep_Theta() line 135 in /Users/liul/soft/petsc/src/ts/impls/implicit/theta/theta.c</div><div>[0]PETSC ERROR: TSEvaluateStep() line 2508 in /Users/liul/soft/petsc/src/ts/interface/ts.c</div>
<div>[0]PETSC ERROR: TSAdaptChoose_Lulu() line 30 in src/ts/examples/tutorials/aspin/adaptlulu.c</div><div>[0]PETSC ERROR: TSAdaptChoose() line 521 in /Users/liul/soft/petsc/src/ts/adapt/interface/tsadapt.c</div><div>[0]PETSC ERROR: TSStep_Theta() line 196 in /Users/liul/soft/petsc/src/ts/impls/implicit/theta/theta.c</div>
<div>[0]PETSC ERROR: TSStep() line 2458 in /Users/liul/soft/petsc/src/ts/interface/ts.c</div><div>[0]PETSC ERROR: TSSolve() line 2583 in /Users/liul/soft/petsc/src/ts/interface/ts.c</div><div>[0]PETSC ERROR: main() line 280 in src/ts/examples/tutorials/case1.c</div>
<div>application called MPI_Abort(MPI_COMM_WORLD, 83) - process 0</div><div>[cli_0]: aborting job:</div><div>application called MPI_Abort(MPI_COMM_WORLD, 83) - process 0</div></div><div><br></div><div><br></div><div><br></div>
<div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">Presumably you are calling<br>
TSEvaluateStep, but if you are trying to step with a first-order method,<br>
you can't use "zeroth order" as an estimate of the error.<br>
<div class="im"><br>
> Is there any substitute for -ts_theta_adapt such that I could have my own<br>
> time-step adaptivity for backward Euler?<br>
<br>
</div>Why not use '-ts_type arkimex -ts_arkimex_type 1bee', which uses an<br>
extrapolation-based error estimator? If you want something else, just<br>
write it as a Runge-Kutta method like '1bee'.<br></blockquote><div><br></div><div><br></div><div style>If I use '-ts_type arkimex -ts_arkimex_type 1bee', the time-step becomes too small, and I need too many iterations for the nonlinear system, so I can not accept it.</div>
<div style><br></div><div style>My adaptive scheme :</div><div style><br></div><div style>If local or global snes ( nonlinear preconditioners includes a subsnes for each subdomain) does not converge within 15 steps or diverge, the time-step will be half, and time step will be doubled if the previous two time steps are not reduced.</div>
<div style><br></div><div style>Or my adaptive scheme will based on the correction max(\delta x) during Newton iterations.</div><div style><br></div><div style><br></div><div style><br></div></div><br clear="all"><div><br>
</div>-- <br><div dir="ltr"><div>Best wishes,<br>Lulu Liu<br>Applied Mathematics and Computational Science</div>
<div>King Abdullah University of Science and Technology<br>Tel：＋966－0544701599</div></div>
</div></div>
<br>
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