Date: 2022-08-02T03:15:09+00:00

Actual source code: adaptglee.c

      1: #include <petsc/private/tsimpl.h>
      2: #include <petscdm.h>

      4: typedef struct {
      5:   Vec Y;
      6: } TSAdapt_GLEE;

      8: static PetscErrorCode TSAdaptChoose_GLEE(TSAdapt adapt,TS ts,PetscReal h,PetscInt *next_sc,PetscReal *next_h,PetscBool *accept,PetscReal *wlte,PetscReal *wltea,PetscReal *wlter)
      9: {
     10:   TSAdapt_GLEE   *glee = (TSAdapt_GLEE*)adapt->data;
     11:   Vec            X,Y,E;
     12:   PetscReal      enorm,enorma,enormr,hfac_lte,hfac_ltea,hfac_lter,h_lte,safety;
     13:   PetscInt       order;
     14:   PetscBool      bGTEMethod;

     16:   *next_sc = 0; /* Reuse the same order scheme */
     17:   safety = adapt->safety;
     18:   PetscObjectTypeCompare((PetscObject)ts,TSGLEE,&bGTEMethod);
     19:   order = adapt->candidates.order[0];

     21:   if (bGTEMethod) {/* the method is of GLEE type */
     22:     DM dm;

     24:     TSGetSolution(ts,&X);
     25:     if (!glee->Y && adapt->glee_use_local) {
     26:       VecDuplicate(X,&glee->Y);/*create vector to store previous step global error*/
     27:       VecZeroEntries(glee->Y); /*set error to zero on the first step - may not work if error is not zero initially*/
     28:     }
     29:     TSGetDM(ts,&dm);
     30:     DMGetGlobalVector(dm,&E);
     31:     TSGetTimeError(ts,0,&E);

     33:     if (adapt->glee_use_local) VecAXPY(E,-1.0,glee->Y); /* local error = current error - previous step error */

     35:     /* this should be called with the solution at the beginning of the step too*/
     36:     TSErrorWeightedENorm(ts,E,X,X,adapt->wnormtype,&enorm,&enorma,&enormr);
     37:     DMRestoreGlobalVector(dm,&E);
     38:   } else {
     39:     /* the method is NOT of GLEE type; use the stantard basic augmented by separate atol and rtol */
     40:     TSGetSolution(ts,&X);
     41:     if (!glee->Y) VecDuplicate(X,&glee->Y);
     42:     Y     = glee->Y;
     43:     TSEvaluateStep(ts,order-1,Y,NULL);
     44:     TSErrorWeightedNorm(ts,X,Y,adapt->wnormtype,&enorm,&enorma,&enormr);
     45:   }

     47:   if (enorm < 0) {
     48:     *accept  = PETSC_TRUE;
     49:     *next_h  = h;            /* Reuse the old step */
     50:     *wlte    = -1;           /* Weighted error was not evaluated */
     51:     *wltea   = -1;           /* Weighted absolute error was not evaluated */
     52:     *wlter   = -1;           /* Weighted relative error was not evaluated */
     53:     return 0;
     54:   }

     56:   if (enorm > 1. || enorma > 1. || enormr > 1.) {
     57:     if (!*accept) safety *= adapt->reject_safety; /* The last attempt also failed, shorten more aggressively */
     58:     if (h < (1 + PETSC_SQRT_MACHINE_EPSILON)*adapt->dt_min) {
     59:       PetscInfo(adapt,"Estimated scaled truncation error [combined, absolute, relative]] [%g, %g, %g], accepting because step size %g is at minimum\n",(double)enorm,(double)enorma,(double)enormr,(double)h);
     60:       *accept = PETSC_TRUE;
     61:     } else if (adapt->always_accept) {
     62:       PetscInfo(adapt,"Estimated scaled truncation error [combined, absolute, relative]] [%g, %g, %g], accepting step of size %g because always_accept is set\n",(double)enorm,(double)enorma,(double)enormr,(double)h);
     63:       *accept = PETSC_TRUE;
     64:     } else {
     65:       PetscInfo(adapt,"Estimated scaled truncation error [combined, absolute, relative]] [%g, %g, %g], rejecting step of size %g\n",(double)enorm,(double)enorma,(double)enormr,(double)h);
     66:       *accept = PETSC_FALSE;
     67:     }
     68:   } else {
     69:     PetscInfo(adapt,"Estimated scaled truncation error [combined, absolute, relative] [%g, %g, %g], accepting step of size %g\n",(double)enorm,(double)enorma,(double)enormr,(double)h);
     70:     *accept = PETSC_TRUE;
     71:   }

     73:   if (bGTEMethod) {
     74:     if (*accept == PETSC_TRUE && adapt->glee_use_local) {
     75:       /* If step is accepted, then overwrite previous step error with the current error to be used on the next step */
     76:       /* WARNING: if the adapters are composable, then the accept test will not be reliable*/
     77:       TSGetTimeError(ts,0,&glee->Y);
     78:     }

     80:     /* The optimal new step based on the current global truncation error. */
     81:     if (enorm > 0) {
     82:       /* factor based on the absolute tolerance */
     83:       hfac_ltea = safety * PetscPowReal(1./enorma,((PetscReal)1)/(order+1));
     84:       /* factor based on the relative tolerance */
     85:       hfac_lter = safety * PetscPowReal(1./enormr,((PetscReal)1)/(order+1));
     86:       /* pick the minimum time step among the relative and absolute tolerances */
     87:       hfac_lte  = PetscMin(hfac_ltea,hfac_lter);
     88:     } else {
     89:       hfac_lte = safety * PETSC_INFINITY;
     90:     }
     91:     h_lte = h * PetscClipInterval(hfac_lte,adapt->clip[0],adapt->clip[1]);
     92:     *next_h = PetscClipInterval(h_lte,adapt->dt_min,adapt->dt_max);
     93:   } else {
     94:     /* The optimal new step based purely on local truncation error for this step. */
     95:     if (enorm > 0) {
     96:       /* factor based on the absolute tolerance */
     97:       hfac_ltea = safety * PetscPowReal(enorma,((PetscReal)-1)/order);
     98:       /* factor based on the relative tolerance */
     99:       hfac_lter = safety * PetscPowReal(enormr,((PetscReal)-1)/order);
    100:       /* pick the minimum time step among the relative and absolute tolerances */
    101:       hfac_lte  = PetscMin(hfac_ltea,hfac_lter);
    102:     } else {
    103:       hfac_lte = safety * PETSC_INFINITY;
    104:     }
    105:     h_lte = h * PetscClipInterval(hfac_lte,adapt->clip[0],adapt->clip[1]);
    106:     *next_h = PetscClipInterval(h_lte,adapt->dt_min,adapt->dt_max);
    107:   }
    108:   *wlte   = enorm;
    109:   *wltea  = enorma;
    110:   *wlter  = enormr;
    111:   return 0;
    112: }

    114: static PetscErrorCode TSAdaptReset_GLEE(TSAdapt adapt)
    115: {
    116:   TSAdapt_GLEE  *glee = (TSAdapt_GLEE*)adapt->data;

    118:   VecDestroy(&glee->Y);
    119:   return 0;
    120: }

    122: static PetscErrorCode TSAdaptDestroy_GLEE(TSAdapt adapt)
    123: {
    124:   TSAdaptReset_GLEE(adapt);
    125:   PetscFree(adapt->data);
    126:   return 0;
    127: }

    129: /*MC
    130:    TSADAPTGLEE - GLEE adaptive controller for time stepping

    132:    Level: intermediate

    134: .seealso: TS, TSAdapt, TSGetAdapt()
    135: M*/
    136: PETSC_EXTERN PetscErrorCode TSAdaptCreate_GLEE(TSAdapt adapt)
    137: {
    138:   TSAdapt_GLEE  *glee;

    140:   PetscNewLog(adapt,&glee);
    141:   adapt->data         = (void*)glee;
    142:   adapt->ops->choose  = TSAdaptChoose_GLEE;
    143:   adapt->ops->reset   = TSAdaptReset_GLEE;
    144:   adapt->ops->destroy = TSAdaptDestroy_GLEE;
    145:   return 0;
    146: }