Date: 2022-03-04T17:39:46+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;
     12:   Vec            X,Y,E;
     13:   PetscReal      enorm,enorma,enormr,hfac_lte,hfac_ltea,hfac_lter,h_lte,safety;
     14:   PetscInt       order;
     15:   PetscBool      bGTEMethod;

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

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

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

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

     37:     /* this should be called with the solution at the beginning of the step too*/
     38:     TSErrorWeightedENorm(ts,E,X,X,adapt->wnormtype,&enorm,&enorma,&enormr);
     39:     DMRestoreGlobalVector(dm,&E);
     40:   } else {
     41:     /* the method is NOT of GLEE type; use the stantard basic augmented by separate atol and rtol */
     42:     TSGetSolution(ts,&X);
     43:     if (!glee->Y) {VecDuplicate(X,&glee->Y);}
     44:     Y     = glee->Y;
     45:     TSEvaluateStep(ts,order-1,Y,NULL);
     46:     TSErrorWeightedNorm(ts,X,Y,adapt->wnormtype,&enorm,&enorma,&enormr);
     47:   }

     49:   if (enorm < 0) {
     50:     *accept  = PETSC_TRUE;
     51:     *next_h  = h;            /* Reuse the old step */
     52:     *wlte    = -1;           /* Weighted error was not evaluated */
     53:     *wltea   = -1;           /* Weighted absolute error was not evaluated */
     54:     *wlter   = -1;           /* Weighted relative error was not evaluated */
     55:     return(0);
     56:   }

     58:   if (enorm > 1. || enorma > 1. || enormr > 1.) {
     59:     if (!*accept) safety *= adapt->reject_safety; /* The last attempt also failed, shorten more aggressively */
     60:     if (h < (1 + PETSC_SQRT_MACHINE_EPSILON)*adapt->dt_min) {
     61:       PetscInfo4(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);
     62:       *accept = PETSC_TRUE;
     63:     } else if (adapt->always_accept) {
     64:       PetscInfo4(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);
     65:       *accept = PETSC_TRUE;
     66:     } else {
     67:       PetscInfo4(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);
     68:       *accept = PETSC_FALSE;
     69:     }
     70:   } else {
     71:     PetscInfo4(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);
     72:     *accept = PETSC_TRUE;
     73:   }

     75:   if (bGTEMethod) {
     76:     if (*accept == PETSC_TRUE && adapt->glee_use_local) {
     77:       /* If step is accepted, then overwrite previous step error with the current error to be used on the next step */
     78:       /* WARNING: if the adapters are composable, then the accept test will not be reliable*/
     79:       TSGetTimeError(ts,0,&glee->Y);
     80:     }

     82:     /* The optimal new step based on the current global truncation error. */
     83:     if (enorm > 0) {
     84:       /* factor based on the absolute tolerance */
     85:       hfac_ltea = safety * PetscPowReal(1./enorma,((PetscReal)1)/(order+1));
     86:       /* factor based on the relative tolerance */
     87:       hfac_lter = safety * PetscPowReal(1./enormr,((PetscReal)1)/(order+1));
     88:       /* pick the minimum time step among the relative and absolute tolerances */
     89:       hfac_lte  = PetscMin(hfac_ltea,hfac_lter);
     90:     } else {
     91:       hfac_lte = safety * PETSC_INFINITY;
     92:     }
     93:     h_lte = h * PetscClipInterval(hfac_lte,adapt->clip[0],adapt->clip[1]);
     94:     *next_h = PetscClipInterval(h_lte,adapt->dt_min,adapt->dt_max);
     95:   } else {
     96:     /* The optimal new step based purely on local truncation error for this step. */
     97:     if (enorm > 0) {
     98:       /* factor based on the absolute tolerance */
     99:       hfac_ltea = safety * PetscPowReal(enorma,((PetscReal)-1)/order);
    100:       /* factor based on the relative tolerance */
    101:       hfac_lter = safety * PetscPowReal(enormr,((PetscReal)-1)/order);
    102:       /* pick the minimum time step among the relative and absolute tolerances */
    103:       hfac_lte  = PetscMin(hfac_ltea,hfac_lter);
    104:     } else {
    105:       hfac_lte = safety * PETSC_INFINITY;
    106:     }
    107:     h_lte = h * PetscClipInterval(hfac_lte,adapt->clip[0],adapt->clip[1]);
    108:     *next_h = PetscClipInterval(h_lte,adapt->dt_min,adapt->dt_max);
    109:   }
    110:   *wlte   = enorm;
    111:   *wltea  = enorma;
    112:   *wlter  = enormr;
    113:   return(0);
    114: }

    116: static PetscErrorCode TSAdaptReset_GLEE(TSAdapt adapt)
    117: {
    118:   TSAdapt_GLEE  *glee = (TSAdapt_GLEE*)adapt->data;

    122:   VecDestroy(&glee->Y);
    123:   return(0);
    124: }

    126: static PetscErrorCode TSAdaptDestroy_GLEE(TSAdapt adapt)
    127: {

    131:   TSAdaptReset_GLEE(adapt);
    132:   PetscFree(adapt->data);
    133:   return(0);
    134: }

    136: /*MC
    137:    TSADAPTGLEE - GLEE adaptive controller for time stepping

    139:    Level: intermediate

    141: .seealso: TS, TSAdapt, TSGetAdapt()
    142: M*/
    143: PETSC_EXTERN PetscErrorCode TSAdaptCreate_GLEE(TSAdapt adapt)
    144: {
    146:   TSAdapt_GLEE  *glee;

    149:   PetscNewLog(adapt,&glee);
    150:   adapt->data         = (void*)glee;
    151:   adapt->ops->choose  = TSAdaptChoose_GLEE;
    152:   adapt->ops->reset   = TSAdaptReset_GLEE;
    153:   adapt->ops->destroy = TSAdaptDestroy_GLEE;
    154:   return(0);
    155: }