Date: 2013-07-02T14:52:00+00:00

Actual source code: tsadapt.c
petsc-3.4.2 2013-07-02

      2: #include <petsc-private/tsimpl.h> /*I  "petscts.h" I*/

      4: static PetscFunctionList TSAdaptList;
      5: static PetscBool         TSAdaptPackageInitialized;
      6: static PetscBool         TSAdaptRegisterAllCalled;
      7: static PetscClassId      TSADAPT_CLASSID;

      9: PETSC_EXTERN PetscErrorCode TSAdaptCreate_Basic(TSAdapt);
     10: PETSC_EXTERN PetscErrorCode TSAdaptCreate_None(TSAdapt);
     11: PETSC_EXTERN PetscErrorCode TSAdaptCreate_CFL(TSAdapt);

     15: /*@C
     16:    TSAdaptRegister -  adds a TSAdapt implementation

     18:    Not Collective

     20:    Input Parameters:
     21: +  name_scheme - name of user-defined adaptivity scheme
     22: -  routine_create - routine to create method context

     24:    Notes:
     25:    TSAdaptRegister() may be called multiple times to add several user-defined families.

     27:    Sample usage:
     28: .vb
     29:    TSAdaptRegister("my_scheme",MySchemeCreate);
     30: .ve

     32:    Then, your scheme can be chosen with the procedural interface via
     33: $     TSAdaptSetType(ts,"my_scheme")
     34:    or at runtime via the option
     35: $     -ts_adapt_type my_scheme

     37:    Level: advanced

     39: .keywords: TSAdapt, register

     41: .seealso: TSAdaptRegisterAll()
     42: @*/
     43: PetscErrorCode  TSAdaptRegister(const char sname[],PetscErrorCode (*function)(TSAdapt))
     44: {

     48:   PetscFunctionListAdd(&TSAdaptList,sname,function);
     49:   return(0);
     50: }

     54: /*@C
     55:   TSAdaptRegisterAll - Registers all of the adaptivity schemes in TSAdapt

     57:   Not Collective

     59:   Level: advanced

     61: .keywords: TSAdapt, register, all

     63: .seealso: TSAdaptRegisterDestroy()
     64: @*/
     65: PetscErrorCode  TSAdaptRegisterAll(void)
     66: {

     70:   TSAdaptRegister(TSADAPTBASIC,TSAdaptCreate_Basic);
     71:   TSAdaptRegister(TSADAPTNONE, TSAdaptCreate_None);
     72:   TSAdaptRegister(TSADAPTCFL,  TSAdaptCreate_CFL);
     73:   return(0);
     74: }

     78: /*@C
     79:   TSFinalizePackage - This function destroys everything in the TS package. It is
     80:   called from PetscFinalize().

     82:   Level: developer

     84: .keywords: Petsc, destroy, package
     85: .seealso: PetscFinalize()
     86: @*/
     87: PetscErrorCode  TSAdaptFinalizePackage(void)
     88: {

     92:   PetscFunctionListDestroy(&TSAdaptList);
     93:   TSAdaptPackageInitialized = PETSC_FALSE;
     94:   TSAdaptRegisterAllCalled  = PETSC_FALSE;
     95:   return(0);
     96: }

    100: /*@C
    101:   TSAdaptInitializePackage - This function initializes everything in the TSAdapt package. It is
    102:   called from PetscDLLibraryRegister() when using dynamic libraries, and on the first call to
    103:   TSCreate_GL() when using static libraries.

    105:   Level: developer

    107: .keywords: TSAdapt, initialize, package
    108: .seealso: PetscInitialize()
    109: @*/
    110: PetscErrorCode  TSAdaptInitializePackage(void)
    111: {

    115:   if (TSAdaptPackageInitialized) return(0);
    116:   TSAdaptPackageInitialized = PETSC_TRUE;
    117:   PetscClassIdRegister("TSAdapt",&TSADAPT_CLASSID);
    118:   TSAdaptRegisterAll();
    119:   PetscRegisterFinalize(TSAdaptFinalizePackage);
    120:   return(0);
    121: }

    125: PetscErrorCode  TSAdaptSetType(TSAdapt adapt,TSAdaptType type)
    126: {
    127:   PetscErrorCode ierr,(*r)(TSAdapt);

    130:   PetscFunctionListFind(TSAdaptList,type,&r);
    131:   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unknown TSAdapt type \"%s\" given",type);
    132:   if (((PetscObject)adapt)->type_name) {(*adapt->ops->destroy)(adapt);}
    133:   (*r)(adapt);
    134:   PetscObjectChangeTypeName((PetscObject)adapt,type);
    135:   return(0);
    136: }

    140: PetscErrorCode  TSAdaptSetOptionsPrefix(TSAdapt adapt,const char prefix[])
    141: {

    145:   PetscObjectSetOptionsPrefix((PetscObject)adapt,prefix);
    146:   return(0);
    147: }

    151: /*@C
    152:   TSAdaptLoad - Loads a TSAdapt that has been stored in binary  with TSAdaptView().

    154:   Collective on PetscViewer

    156:   Input Parameters:
    157: + newdm - the newly loaded TSAdapt, this needs to have been created with TSAdaptCreate() or
    158:            some related function before a call to TSAdaptLoad().
    159: - viewer - binary file viewer, obtained from PetscViewerBinaryOpen() or
    160:            HDF5 file viewer, obtained from PetscViewerHDF5Open()

    162:    Level: intermediate

    164:   Notes:
    165:    The type is determined by the data in the file, any type set into the TSAdapt before this call is ignored.

    167:   Notes for advanced users:
    168:   Most users should not need to know the details of the binary storage
    169:   format, since TSAdaptLoad() and TSAdaptView() completely hide these details.
    170:   But for anyone who's interested, the standard binary matrix storage
    171:   format is
    172: .vb
    173:      has not yet been determined
    174: .ve

    176: .seealso: PetscViewerBinaryOpen(), TSAdaptView(), MatLoad(), VecLoad()
    177: @*/
    178: PetscErrorCode  TSAdaptLoad(TSAdapt tsadapt, PetscViewer viewer)
    179: {
    181:   PetscBool      isbinary;
    182:   char           type[256];

    187:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
    188:   if (!isbinary) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");

    190:   PetscViewerBinaryRead(viewer,type,256,PETSC_CHAR);
    191:   TSAdaptSetType(tsadapt, type);
    192:   if (tsadapt->ops->load) {
    193:     (*tsadapt->ops->load)(tsadapt,viewer);
    194:   }
    195:   return(0);
    196: }

    200: PetscErrorCode  TSAdaptView(TSAdapt adapt,PetscViewer viewer)
    201: {
    203:   PetscBool      iascii,isbinary;

    206:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
    207:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
    208:   if (iascii) {
    209:     PetscObjectPrintClassNamePrefixType((PetscObject)adapt,viewer,"TSAdapt Object");
    210:     PetscViewerASCIIPrintf(viewer,"  number of candidates %D\n",adapt->candidates.n);
    211:     if (adapt->ops->view) {
    212:       PetscViewerASCIIPushTab(viewer);
    213:       (*adapt->ops->view)(adapt,viewer);
    214:       PetscViewerASCIIPopTab(viewer);
    215:     }
    216:   } else if (isbinary) {
    217:     char type[256];

    219:     /* need to save FILE_CLASS_ID for adapt class */
    220:     PetscStrncpy(type,((PetscObject)adapt)->type_name,256);
    221:     PetscViewerBinaryWrite(viewer,type,256,PETSC_CHAR,PETSC_FALSE);
    222:   } else if (adapt->ops->view) {
    223:     (*adapt->ops->view)(adapt,viewer);
    224:   }
    225:   return(0);
    226: }

    230: PetscErrorCode  TSAdaptDestroy(TSAdapt *adapt)
    231: {

    235:   if (!*adapt) return(0);
    237:   if (--((PetscObject)(*adapt))->refct > 0) {*adapt = 0; return(0);}
    238:   if ((*adapt)->ops->destroy) {(*(*adapt)->ops->destroy)(*adapt);}
    239:   PetscViewerDestroy(&(*adapt)->monitor);
    240:   PetscHeaderDestroy(adapt);
    241:   return(0);
    242: }

    246: /*@
    247:    TSAdaptSetMonitor - Monitor the choices made by the adaptive controller

    249:    Collective on TSAdapt

    251:    Input Arguments:
    252: +  adapt - adaptive controller context
    253: -  flg - PETSC_TRUE to active a monitor, PETSC_FALSE to disable

    255:    Level: intermediate

    257: .seealso: TSAdaptChoose()
    258: @*/
    259: PetscErrorCode TSAdaptSetMonitor(TSAdapt adapt,PetscBool flg)
    260: {

    264:   if (flg) {
    265:     if (!adapt->monitor) {PetscViewerASCIIOpen(PetscObjectComm((PetscObject)adapt),"stdout",&adapt->monitor);}
    266:   } else {
    267:     PetscViewerDestroy(&adapt->monitor);
    268:   }
    269:   return(0);
    270: }

    274: /*@C
    275:    TSAdaptSetCheckStage - set a callback to check convergence for a stage

    277:    Logically collective on TSAdapt

    279:    Input Arguments:
    280: +  adapt - adaptive controller context
    281: -  func - stage check function

    283:    Arguments of func:
    284: $  PetscErrorCode func(TSAdapt adapt,TS ts,PetscBool *accept)

    286: +  adapt - adaptive controller context
    287: .  ts - time stepping context
    288: -  accept - pending choice of whether to accept, can be modified by this routine

    290:    Level: advanced

    292: .seealso: TSAdaptChoose()
    293: @*/
    294: PetscErrorCode TSAdaptSetCheckStage(TSAdapt adapt,PetscErrorCode (*func)(TSAdapt,TS,PetscBool*))
    295: {

    299:   adapt->ops->checkstage = func;
    300:   return(0);
    301: }

    305: /*@
    306:    TSAdaptSetStepLimits - Set minimum and maximum step sizes to be considered by the controller

    308:    Logically Collective

    310:    Input Arguments:
    311: +  adapt - time step adaptivity context, usually gotten with TSGetAdapt()
    312: .  hmin - minimum time step
    313: -  hmax - maximum time step

    315:    Options Database Keys:
    316: +  -ts_adapt_dt_min - minimum time step
    317: -  -ts_adapt_dt_max - maximum time step

    319:    Level: intermediate

    321: .seealso: TSAdapt
    322: @*/
    323: PetscErrorCode TSAdaptSetStepLimits(TSAdapt adapt,PetscReal hmin,PetscReal hmax)
    324: {

    327:   if (hmin != PETSC_DECIDE) adapt->dt_min = hmin;
    328:   if (hmax != PETSC_DECIDE) adapt->dt_max = hmax;
    329:   return(0);
    330: }

    334: /*@
    335:    TSAdaptSetFromOptions - Sets various TSAdapt parameters from user options.

    337:    Collective on TSAdapt

    339:    Input Parameter:
    340: .  adapt - the TSAdapt context

    342:    Options Database Keys:
    343: .  -ts_adapt_type <type> - basic

    345:    Level: advanced

    347:    Notes:
    348:    This function is automatically called by TSSetFromOptions()

    350: .keywords: TS, TSGetAdapt(), TSAdaptSetType()

    352: .seealso: TSGetType()
    353: @*/
    354: PetscErrorCode  TSAdaptSetFromOptions(TSAdapt adapt)
    355: {
    357:   char           type[256] = TSADAPTBASIC;
    358:   PetscBool      set,flg;

    361:   /* This should use PetscOptionsBegin() if/when this becomes an object used outside of TS, but currently this
    362:   * function can only be called from inside TSSetFromOptions_GL()  */
    363:   PetscOptionsHead("TS Adaptivity options");
    364:   PetscOptionsList("-ts_adapt_type","Algorithm to use for adaptivity","TSAdaptSetType",TSAdaptList,
    365:                           ((PetscObject)adapt)->type_name ? ((PetscObject)adapt)->type_name : type,type,sizeof(type),&flg);
    366:   if (flg || !((PetscObject)adapt)->type_name) {
    367:     TSAdaptSetType(adapt,type);
    368:   }
    369:   if (adapt->ops->setfromoptions) {(*adapt->ops->setfromoptions)(adapt);}
    370:   PetscOptionsReal("-ts_adapt_dt_min","Minimum time step considered","TSAdaptSetStepLimits",adapt->dt_min,&adapt->dt_min,NULL);
    371:   PetscOptionsReal("-ts_adapt_dt_max","Maximum time step considered","TSAdaptSetStepLimits",adapt->dt_max,&adapt->dt_max,NULL);
    372:   PetscOptionsReal("-ts_adapt_scale_solve_failed","Scale step by this factor if solve fails","",adapt->scale_solve_failed,&adapt->scale_solve_failed,NULL);
    373:   PetscOptionsBool("-ts_adapt_monitor","Print choices made by adaptive controller","TSAdaptSetMonitor",adapt->monitor ? PETSC_TRUE : PETSC_FALSE,&flg,&set);
    374:   if (set) {TSAdaptSetMonitor(adapt,flg);}
    375:   PetscOptionsTail();
    376:   return(0);
    377: }

    381: /*@
    382:    TSAdaptCandidatesClear - clear any previously set candidate schemes

    384:    Logically Collective

    386:    Input Argument:
    387: .  adapt - adaptive controller

    389:    Level: developer

    391: .seealso: TSAdapt, TSAdaptCreate(), TSAdaptCandidateAdd(), TSAdaptChoose()
    392: @*/
    393: PetscErrorCode TSAdaptCandidatesClear(TSAdapt adapt)
    394: {

    398:   PetscMemzero(&adapt->candidates,sizeof(adapt->candidates));
    399:   return(0);
    400: }

    404: /*@C
    405:    TSAdaptCandidateAdd - add a candidate scheme for the adaptive controller to select from

    407:    Logically Collective

    409:    Input Arguments:
    410: +  adapt - time step adaptivity context, obtained with TSGetAdapt() or TSAdaptCreate()
    411: .  name - name of the candidate scheme to add
    412: .  order - order of the candidate scheme
    413: .  stageorder - stage order of the candidate scheme
    414: .  ccfl - stability coefficient relative to explicit Euler, used for CFL constraints
    415: .  cost - relative measure of the amount of work required for the candidate scheme
    416: -  inuse - indicates that this scheme is the one currently in use, this flag can only be set for one scheme

    418:    Note:
    419:    This routine is not available in Fortran.

    421:    Level: developer

    423: .seealso: TSAdaptCandidatesClear(), TSAdaptChoose()
    424: @*/
    425: PetscErrorCode TSAdaptCandidateAdd(TSAdapt adapt,const char name[],PetscInt order,PetscInt stageorder,PetscReal ccfl,PetscReal cost,PetscBool inuse)
    426: {
    427:   PetscInt c;

    431:   if (order < 1) SETERRQ1(PetscObjectComm((PetscObject)adapt),PETSC_ERR_ARG_OUTOFRANGE,"Classical order %D must be a positive integer",order);
    432:   if (inuse) {
    433:     if (adapt->candidates.inuse_set) SETERRQ(PetscObjectComm((PetscObject)adapt),PETSC_ERR_ARG_WRONGSTATE,"Cannot set the inuse method twice, maybe forgot to call TSAdaptCandidatesClear()");
    434:     adapt->candidates.inuse_set = PETSC_TRUE;
    435:   }
    436:   /* first slot if this is the current scheme, otherwise the next available slot */
    437:   c = inuse ? 0 : !adapt->candidates.inuse_set + adapt->candidates.n;

    439:   adapt->candidates.name[c]       = name;
    440:   adapt->candidates.order[c]      = order;
    441:   adapt->candidates.stageorder[c] = stageorder;
    442:   adapt->candidates.ccfl[c]       = ccfl;
    443:   adapt->candidates.cost[c]       = cost;
    444:   adapt->candidates.n++;
    445:   return(0);
    446: }

    450: /*@C
    451:    TSAdaptCandidatesGet - Get the list of candidate orders of accuracy and cost

    453:    Not Collective

    455:    Input Arguments:
    456: .  adapt - time step adaptivity context

    458:    Output Arguments:
    459: +  n - number of candidate schemes, always at least 1
    460: .  order - the order of each candidate scheme
    461: .  stageorder - the stage order of each candidate scheme
    462: .  ccfl - the CFL coefficient of each scheme
    463: -  cost - the relative cost of each scheme

    465:    Level: developer

    467:    Note:
    468:    The current scheme is always returned in the first slot

    470: .seealso: TSAdaptCandidatesClear(), TSAdaptCandidateAdd(), TSAdaptChoose()
    471: @*/
    472: PetscErrorCode TSAdaptCandidatesGet(TSAdapt adapt,PetscInt *n,const PetscInt **order,const PetscInt **stageorder,const PetscReal **ccfl,const PetscReal **cost)
    473: {
    476:   if (n) *n = adapt->candidates.n;
    477:   if (order) *order = adapt->candidates.order;
    478:   if (stageorder) *stageorder = adapt->candidates.stageorder;
    479:   if (ccfl) *ccfl = adapt->candidates.ccfl;
    480:   if (cost) *cost = adapt->candidates.cost;
    481:   return(0);
    482: }

    486: /*@C
    487:    TSAdaptChoose - choose which method and step size to use for the next step

    489:    Logically Collective

    491:    Input Arguments:
    492: +  adapt - adaptive contoller
    493: -  h - current step size

    495:    Output Arguments:
    496: +  next_sc - scheme to use for the next step
    497: .  next_h - step size to use for the next step
    498: -  accept - PETSC_TRUE to accept the current step, PETSC_FALSE to repeat the current step with the new step size

    500:    Note:
    501:    The input value of parameter accept is retained from the last time step, so it will be PETSC_FALSE if the step is
    502:    being retried after an initial rejection.

    504:    Level: developer

    506: .seealso: TSAdapt, TSAdaptCandidatesClear(), TSAdaptCandidateAdd()
    507: @*/
    508: PetscErrorCode TSAdaptChoose(TSAdapt adapt,TS ts,PetscReal h,PetscInt *next_sc,PetscReal *next_h,PetscBool *accept)
    509: {
    511:   PetscReal      wlte = -1.0;

    519:   if (adapt->candidates.n < 1) SETERRQ1(PetscObjectComm((PetscObject)adapt),PETSC_ERR_ARG_WRONGSTATE,"%D candidates have been registered",adapt->candidates.n);
    520:   if (!adapt->candidates.inuse_set) SETERRQ1(PetscObjectComm((PetscObject)adapt),PETSC_ERR_ARG_WRONGSTATE,"The current in-use scheme is not among the %D candidates",adapt->candidates.n);
    521:   (*adapt->ops->choose)(adapt,ts,h,next_sc,next_h,accept,&wlte);
    522:   if (*accept && ts->exact_final_time == TS_EXACTFINALTIME_MATCHSTEP) {
    523:     /* Reduce time step if it overshoots max time */
    524:     PetscReal max_time = ts->max_time;
    525:     PetscReal next_dt  = 0.0;
    526:     if (ts->ptime + ts->time_step + *next_h >= max_time) {
    527:       next_dt = max_time - (ts->ptime + ts->time_step);
    528:       if (next_dt > PETSC_SMALL) *next_h = next_dt;
    529:       else ts->reason = TS_CONVERGED_TIME;
    530:     }
    531:   }
    532:   if (*next_sc < 0 || adapt->candidates.n <= *next_sc) SETERRQ2(PetscObjectComm((PetscObject)adapt),PETSC_ERR_ARG_OUTOFRANGE,"Chosen scheme %D not in valid range 0..%D",*next_sc,adapt->candidates.n-1);
    533:   if (!(*next_h > 0.)) SETERRQ1(PetscObjectComm((PetscObject)adapt),PETSC_ERR_ARG_OUTOFRANGE,"Computed step size %G must be positive",*next_h);

    535:   if (adapt->monitor) {
    536:     PetscViewerASCIIAddTab(adapt->monitor,((PetscObject)adapt)->tablevel);
    537:     if (wlte < 0) {
    538:       PetscViewerASCIIPrintf(adapt->monitor,"    TSAdapt '%s': step %3D %s t=%-11g+%10.3e family='%s' scheme=%D:'%s' dt=%-10g\n",((PetscObject)adapt)->type_name,ts->steps,*accept ? "accepted" : "rejected",(double)ts->ptime,(double)h,((PetscObject)ts)->type_name,*next_sc,adapt->candidates.name[*next_sc],(double)*next_h);
    539:     } else {
    540:       PetscViewerASCIIPrintf(adapt->monitor,"    TSAdapt '%s': step %3D %s t=%-11g+%10.3e wlte=%5.3g family='%s' scheme=%D:'%s' dt=%-10.3e\n",((PetscObject)adapt)->type_name,ts->steps,*accept ? "accepted" : "rejected",(double)ts->ptime,(double)h,(double)wlte,((PetscObject)ts)->type_name,*next_sc,adapt->candidates.name[*next_sc],(double)*next_h);
    541:     }
    542:     PetscViewerASCIISubtractTab(adapt->monitor,((PetscObject)adapt)->tablevel);
    543:   }
    544:   return(0);
    545: }

    549: /*@
    550:    TSAdaptCheckStage - checks whether to accept a stage, (e.g. reject and change time step size if nonlinear solve fails)

    552:    Collective

    554:    Input Arguments:
    555: +  adapt - adaptive controller context
    556: -  ts - time stepper

    558:    Output Arguments:
    559: .  accept - PETSC_TRUE to accept the stage, PETSC_FALSE to reject

    561:    Level: developer

    563: .seealso:
    564: @*/
    565: PetscErrorCode TSAdaptCheckStage(TSAdapt adapt,TS ts,PetscBool *accept)
    566: {
    567:   PetscErrorCode      ierr;
    568:   SNES                snes;
    569:   SNESConvergedReason snesreason;

    572:   *accept = PETSC_TRUE;
    573:   TSGetSNES(ts,&snes);
    574:   SNESGetConvergedReason(snes,&snesreason);
    575:   if (snesreason < 0) {
    576:     PetscReal dt,new_dt;
    577:     *accept = PETSC_FALSE;
    578:     TSGetTimeStep(ts,&dt);
    579:     if (++ts->num_snes_failures >= ts->max_snes_failures && ts->max_snes_failures > 0) {
    580:       ts->reason = TS_DIVERGED_NONLINEAR_SOLVE;
    581:       PetscInfo2(ts,"Step=%D, nonlinear solve solve failures %D greater than current TS allowed, stopping solve\n",ts->steps,ts->num_snes_failures);
    582:       if (adapt->monitor) {
    583:         PetscViewerASCIIAddTab(adapt->monitor,((PetscObject)adapt)->tablevel);
    584:         PetscViewerASCIIPrintf(adapt->monitor,"    TSAdapt '%s': step %3D stage rejected t=%-11g+%10.3e, %D failures exceeds current TS allowed\n",((PetscObject)adapt)->type_name,ts->steps,(double)ts->ptime,dt,ts->num_snes_failures);
    585:         PetscViewerASCIISubtractTab(adapt->monitor,((PetscObject)adapt)->tablevel);
    586:       }
    587:     } else {
    588:       new_dt = dt*adapt->scale_solve_failed;
    589:       TSSetTimeStep(ts,new_dt);
    590:       if (adapt->monitor) {
    591:         PetscViewerASCIIAddTab(adapt->monitor,((PetscObject)adapt)->tablevel);
    592:         PetscViewerASCIIPrintf(adapt->monitor,"    TSAdapt '%s': step %3D stage rejected t=%-11g+%10.3e retrying with dt=%-10.3e\n",((PetscObject)adapt)->type_name,ts->steps,(double)ts->ptime,(double)dt,(double)new_dt);
    593:         PetscViewerASCIISubtractTab(adapt->monitor,((PetscObject)adapt)->tablevel);
    594:       }
    595:     }
    596:   }
    597:   if (adapt->ops->checkstage) {(*adapt->ops->checkstage)(adapt,ts,accept);}
    598:   return(0);
    599: }

    605: /*@
    606:   TSAdaptCreate - create an adaptive controller context for time stepping

    608:   Collective on MPI_Comm

    610:   Input Parameter:
    611: . comm - The communicator

    613:   Output Parameter:
    614: . adapt - new TSAdapt object

    616:   Level: developer

    618:   Notes:
    619:   TSAdapt creation is handled by TS, so users should not need to call this function.

    621: .keywords: TSAdapt, create
    622: .seealso: TSGetAdapt(), TSAdaptSetType(), TSAdaptDestroy()
    623: @*/
    624: PetscErrorCode  TSAdaptCreate(MPI_Comm comm,TSAdapt *inadapt)
    625: {
    627:   TSAdapt        adapt;

    630:   *inadapt = 0;
    631:   PetscHeaderCreate(adapt,_p_TSAdapt,struct _TSAdaptOps,TSADAPT_CLASSID,"TSAdapt","General Linear adaptivity","TS",comm,TSAdaptDestroy,TSAdaptView);

    633:   adapt->dt_min             = 1e-20;
    634:   adapt->dt_max             = 1e50;
    635:   adapt->scale_solve_failed = 0.25;

    637:   *inadapt = adapt;
    638:   return(0);
    639: }