Date: 2022-11-02T11:46:03+00:00

Actual source code: fnbasic.c
slepc-3.18.1 2022-11-02
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain

      6:    This file is part of SLEPc.
      7:    SLEPc is distributed under a 2-clause BSD license (see LICENSE).
      8:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      9: */
     10: /*
     11:    Basic FN routines
     12: */

     14: #include <slepc/private/fnimpl.h>
     15: #include <slepcblaslapack.h>

     17: PetscFunctionList FNList = NULL;
     18: PetscBool         FNRegisterAllCalled = PETSC_FALSE;
     19: PetscClassId      FN_CLASSID = 0;
     20: PetscLogEvent     FN_Evaluate = 0;
     21: static PetscBool  FNPackageInitialized = PETSC_FALSE;

     23: const char *FNParallelTypes[] = {"REDUNDANT","SYNCHRONIZED","FNParallelType","FN_PARALLEL_",NULL};

     25: /*@C
     26:    FNFinalizePackage - This function destroys everything in the Slepc interface
     27:    to the FN package. It is called from SlepcFinalize().

     29:    Level: developer

     31: .seealso: SlepcFinalize()
     32: @*/
     33: PetscErrorCode FNFinalizePackage(void)
     34: {
     35:   PetscFunctionListDestroy(&FNList);
     36:   FNPackageInitialized = PETSC_FALSE;
     37:   FNRegisterAllCalled  = PETSC_FALSE;
     38:   return 0;
     39: }

     41: /*@C
     42:   FNInitializePackage - This function initializes everything in the FN package.
     43:   It is called from PetscDLLibraryRegister() when using dynamic libraries, and
     44:   on the first call to FNCreate() when using static libraries.

     46:   Level: developer

     48: .seealso: SlepcInitialize()
     49: @*/
     50: PetscErrorCode FNInitializePackage(void)
     51: {
     52:   char           logList[256];
     53:   PetscBool      opt,pkg;
     54:   PetscClassId   classids[1];

     56:   if (FNPackageInitialized) return 0;
     57:   FNPackageInitialized = PETSC_TRUE;
     58:   /* Register Classes */
     59:   PetscClassIdRegister("Math Function",&FN_CLASSID);
     60:   /* Register Constructors */
     61:   FNRegisterAll();
     62:   /* Register Events */
     63:   PetscLogEventRegister("FNEvaluate",FN_CLASSID,&FN_Evaluate);
     64:   /* Process Info */
     65:   classids[0] = FN_CLASSID;
     66:   PetscInfoProcessClass("fn",1,&classids[0]);
     67:   /* Process summary exclusions */
     68:   PetscOptionsGetString(NULL,NULL,"-log_exclude",logList,sizeof(logList),&opt);
     69:   if (opt) {
     70:     PetscStrInList("fn",logList,',',&pkg);
     71:     if (pkg) PetscLogEventDeactivateClass(FN_CLASSID);
     72:   }
     73:   /* Register package finalizer */
     74:   PetscRegisterFinalize(FNFinalizePackage);
     75:   return 0;
     76: }

     78: /*@
     79:    FNCreate - Creates an FN context.

     81:    Collective

     83:    Input Parameter:
     84: .  comm - MPI communicator

     86:    Output Parameter:
     87: .  newfn - location to put the FN context

     89:    Level: beginner

     91: .seealso: FNDestroy(), FN
     92: @*/
     93: PetscErrorCode FNCreate(MPI_Comm comm,FN *newfn)
     94: {
     95:   FN             fn;

     98:   *newfn = NULL;
     99:   FNInitializePackage();
    100:   SlepcHeaderCreate(fn,FN_CLASSID,"FN","Math Function","FN",comm,FNDestroy,FNView);

    102:   fn->alpha    = 1.0;
    103:   fn->beta     = 1.0;
    104:   fn->method   = 0;

    106:   fn->nw       = 0;
    107:   fn->cw       = 0;
    108:   fn->data     = NULL;

    110:   *newfn = fn;
    111:   return 0;
    112: }

    114: /*@C
    115:    FNSetOptionsPrefix - Sets the prefix used for searching for all
    116:    FN options in the database.

    118:    Logically Collective on fn

    120:    Input Parameters:
    121: +  fn - the math function context
    122: -  prefix - the prefix string to prepend to all FN option requests

    124:    Notes:
    125:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    126:    The first character of all runtime options is AUTOMATICALLY the
    127:    hyphen.

    129:    Level: advanced

    131: .seealso: FNAppendOptionsPrefix()
    132: @*/
    133: PetscErrorCode FNSetOptionsPrefix(FN fn,const char *prefix)
    134: {
    136:   PetscObjectSetOptionsPrefix((PetscObject)fn,prefix);
    137:   return 0;
    138: }

    140: /*@C
    141:    FNAppendOptionsPrefix - Appends to the prefix used for searching for all
    142:    FN options in the database.

    144:    Logically Collective on fn

    146:    Input Parameters:
    147: +  fn - the math function context
    148: -  prefix - the prefix string to prepend to all FN option requests

    150:    Notes:
    151:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    152:    The first character of all runtime options is AUTOMATICALLY the hyphen.

    154:    Level: advanced

    156: .seealso: FNSetOptionsPrefix()
    157: @*/
    158: PetscErrorCode FNAppendOptionsPrefix(FN fn,const char *prefix)
    159: {
    161:   PetscObjectAppendOptionsPrefix((PetscObject)fn,prefix);
    162:   return 0;
    163: }

    165: /*@C
    166:    FNGetOptionsPrefix - Gets the prefix used for searching for all
    167:    FN options in the database.

    169:    Not Collective

    171:    Input Parameters:
    172: .  fn - the math function context

    174:    Output Parameters:
    175: .  prefix - pointer to the prefix string used is returned

    177:    Note:
    178:    On the Fortran side, the user should pass in a string 'prefix' of
    179:    sufficient length to hold the prefix.

    181:    Level: advanced

    183: .seealso: FNSetOptionsPrefix(), FNAppendOptionsPrefix()
    184: @*/
    185: PetscErrorCode FNGetOptionsPrefix(FN fn,const char *prefix[])
    186: {
    189:   PetscObjectGetOptionsPrefix((PetscObject)fn,prefix);
    190:   return 0;
    191: }

    193: /*@C
    194:    FNSetType - Selects the type for the FN object.

    196:    Logically Collective on fn

    198:    Input Parameters:
    199: +  fn   - the math function context
    200: -  type - a known type

    202:    Notes:
    203:    The default is FNRATIONAL, which includes polynomials as a particular
    204:    case as well as simple functions such as f(x)=x and f(x)=constant.

    206:    Level: intermediate

    208: .seealso: FNGetType()
    209: @*/
    210: PetscErrorCode FNSetType(FN fn,FNType type)
    211: {
    212:   PetscErrorCode (*r)(FN);
    213:   PetscBool      match;

    218:   PetscObjectTypeCompare((PetscObject)fn,type,&match);
    219:   if (match) return 0;

    221:   PetscFunctionListFind(FNList,type,&r);

    224:   PetscTryTypeMethod(fn,destroy);
    225:   PetscMemzero(fn->ops,sizeof(struct _FNOps));

    227:   PetscObjectChangeTypeName((PetscObject)fn,type);
    228:   (*r)(fn);
    229:   return 0;
    230: }

    232: /*@C
    233:    FNGetType - Gets the FN type name (as a string) from the FN context.

    235:    Not Collective

    237:    Input Parameter:
    238: .  fn - the math function context

    240:    Output Parameter:
    241: .  type - name of the math function

    243:    Level: intermediate

    245: .seealso: FNSetType()
    246: @*/
    247: PetscErrorCode FNGetType(FN fn,FNType *type)
    248: {
    251:   *type = ((PetscObject)fn)->type_name;
    252:   return 0;
    253: }

    255: /*@
    256:    FNSetScale - Sets the scaling parameters that define the matematical function.

    258:    Logically Collective on fn

    260:    Input Parameters:
    261: +  fn    - the math function context
    262: .  alpha - inner scaling (argument)
    263: -  beta  - outer scaling (result)

    265:    Notes:
    266:    Given a function f(x) specified by the FN type, the scaling parameters can
    267:    be used to realize the function beta*f(alpha*x). So when these values are given,
    268:    the procedure for function evaluation will first multiply the argument by alpha,
    269:    then evaluate the function itself, and finally scale the result by beta.
    270:    Likewise, these values are also considered when evaluating the derivative.

    272:    If you want to provide only one of the two scaling factors, set the other
    273:    one to 1.0.

    275:    Level: intermediate

    277: .seealso: FNGetScale(), FNEvaluateFunction()
    278: @*/
    279: PetscErrorCode FNSetScale(FN fn,PetscScalar alpha,PetscScalar beta)
    280: {
    285:   fn->alpha = alpha;
    286:   fn->beta  = beta;
    287:   return 0;
    288: }

    290: /*@
    291:    FNGetScale - Gets the scaling parameters that define the matematical function.

    293:    Not Collective

    295:    Input Parameter:
    296: .  fn    - the math function context

    298:    Output Parameters:
    299: +  alpha - inner scaling (argument)
    300: -  beta  - outer scaling (result)

    302:    Level: intermediate

    304: .seealso: FNSetScale()
    305: @*/
    306: PetscErrorCode FNGetScale(FN fn,PetscScalar *alpha,PetscScalar *beta)
    307: {
    309:   if (alpha) *alpha = fn->alpha;
    310:   if (beta)  *beta  = fn->beta;
    311:   return 0;
    312: }

    314: /*@
    315:    FNSetMethod - Selects the method to be used to evaluate functions of matrices.

    317:    Logically Collective on fn

    319:    Input Parameters:
    320: +  fn   - the math function context
    321: -  meth - an index identifying the method

    323:    Options Database Key:
    324: .  -fn_method <meth> - Sets the method

    326:    Notes:
    327:    In some FN types there are more than one algorithms available for computing
    328:    matrix functions. In that case, this function allows choosing the wanted method.

    330:    If meth is currently set to 0 (the default) and the input argument A of
    331:    FNEvaluateFunctionMat() is a symmetric/Hermitian matrix, then the computation
    332:    is done via the eigendecomposition of A, rather than with the general algorithm.

    334:    Level: intermediate

    336: .seealso: FNGetMethod(), FNEvaluateFunctionMat()
    337: @*/
    338: PetscErrorCode FNSetMethod(FN fn,PetscInt meth)
    339: {
    344:   fn->method = meth;
    345:   return 0;
    346: }

    348: /*@
    349:    FNGetMethod - Gets the method currently used in the FN.

    351:    Not Collective

    353:    Input Parameter:
    354: .  fn - the math function context

    356:    Output Parameter:
    357: .  meth - identifier of the method

    359:    Level: intermediate

    361: .seealso: FNSetMethod()
    362: @*/
    363: PetscErrorCode FNGetMethod(FN fn,PetscInt *meth)
    364: {
    367:   *meth = fn->method;
    368:   return 0;
    369: }

    371: /*@
    372:    FNSetParallel - Selects the mode of operation in parallel runs.

    374:    Logically Collective on fn

    376:    Input Parameters:
    377: +  fn    - the math function context
    378: -  pmode - the parallel mode

    380:    Options Database Key:
    381: .  -fn_parallel <mode> - Sets the parallel mode, either 'redundant' or 'synchronized'

    383:    Notes:
    384:    This is relevant only when the function is evaluated on a matrix, with
    385:    either FNEvaluateFunctionMat() or FNEvaluateFunctionMatVec().

    387:    In the 'redundant' parallel mode, all processes will make the computation
    388:    redundantly, starting from the same data, and producing the same result.
    389:    This result may be slightly different in the different processes if using a
    390:    multithreaded BLAS library, which may cause issues in ill-conditioned problems.

    392:    In the 'synchronized' parallel mode, only the first MPI process performs the
    393:    computation and then the computed matrix is broadcast to the other
    394:    processes in the communicator. This communication is done automatically at
    395:    the end of FNEvaluateFunctionMat() or FNEvaluateFunctionMatVec().

    397:    Level: advanced

    399: .seealso: FNEvaluateFunctionMat() or FNEvaluateFunctionMatVec(), FNGetParallel()
    400: @*/
    401: PetscErrorCode FNSetParallel(FN fn,FNParallelType pmode)
    402: {
    405:   fn->pmode = pmode;
    406:   return 0;
    407: }

    409: /*@
    410:    FNGetParallel - Gets the mode of operation in parallel runs.

    412:    Not Collective

    414:    Input Parameter:
    415: .  fn - the math function context

    417:    Output Parameter:
    418: .  pmode - the parallel mode

    420:    Level: advanced

    422: .seealso: FNSetParallel()
    423: @*/
    424: PetscErrorCode FNGetParallel(FN fn,FNParallelType *pmode)
    425: {
    428:   *pmode = fn->pmode;
    429:   return 0;
    430: }

    432: /*@
    433:    FNEvaluateFunction - Computes the value of the function f(x) for a given x.

    435:    Not collective

    437:    Input Parameters:
    438: +  fn - the math function context
    439: -  x  - the value where the function must be evaluated

    441:    Output Parameter:
    442: .  y  - the result of f(x)

    444:    Note:
    445:    Scaling factors are taken into account, so the actual function evaluation
    446:    will return beta*f(alpha*x).

    448:    Level: intermediate

    450: .seealso: FNEvaluateDerivative(), FNEvaluateFunctionMat(), FNSetScale()
    451: @*/
    452: PetscErrorCode FNEvaluateFunction(FN fn,PetscScalar x,PetscScalar *y)
    453: {
    454:   PetscScalar    xf,yf;

    459:   PetscLogEventBegin(FN_Evaluate,fn,0,0,0);
    460:   xf = fn->alpha*x;
    461:   PetscUseTypeMethod(fn,evaluatefunction,xf,&yf);
    462:   *y = fn->beta*yf;
    463:   PetscLogEventEnd(FN_Evaluate,fn,0,0,0);
    464:   return 0;
    465: }

    467: /*@
    468:    FNEvaluateDerivative - Computes the value of the derivative f'(x) for a given x.

    470:    Not Collective

    472:    Input Parameters:
    473: +  fn - the math function context
    474: -  x  - the value where the derivative must be evaluated

    476:    Output Parameter:
    477: .  y  - the result of f'(x)

    479:    Note:
    480:    Scaling factors are taken into account, so the actual derivative evaluation will
    481:    return alpha*beta*f'(alpha*x).

    483:    Level: intermediate

    485: .seealso: FNEvaluateFunction()
    486: @*/
    487: PetscErrorCode FNEvaluateDerivative(FN fn,PetscScalar x,PetscScalar *y)
    488: {
    489:   PetscScalar    xf,yf;

    494:   PetscLogEventBegin(FN_Evaluate,fn,0,0,0);
    495:   xf = fn->alpha*x;
    496:   PetscUseTypeMethod(fn,evaluatederivative,xf,&yf);
    497:   *y = fn->alpha*fn->beta*yf;
    498:   PetscLogEventEnd(FN_Evaluate,fn,0,0,0);
    499:   return 0;
    500: }

    502: static PetscErrorCode FNEvaluateFunctionMat_Sym_Private(FN fn,const PetscScalar *As,PetscScalar *Bs,PetscInt m,PetscBool firstonly)
    503: {
    504:   PetscInt       i,j;
    505:   PetscBLASInt   n,k,ld,lwork,info;
    506:   PetscScalar    *Q,*W,*work,adummy,a,x,y,one=1.0,zero=0.0;
    507:   PetscReal      *eig,dummy;
    508: #if defined(PETSC_USE_COMPLEX)
    509:   PetscReal      *rwork,rdummy;
    510: #endif

    512:   PetscBLASIntCast(m,&n);
    513:   ld = n;
    514:   k = firstonly? 1: n;

    516:   /* workspace query and memory allocation */
    517:   lwork = -1;
    518: #if defined(PETSC_USE_COMPLEX)
    519:   PetscCallBLAS("LAPACKsyev",LAPACKsyev_("V","L",&n,&adummy,&ld,&dummy,&a,&lwork,&rdummy,&info));
    520:   PetscBLASIntCast((PetscInt)PetscRealPart(a),&lwork);
    521:   PetscMalloc5(m,&eig,m*m,&Q,m*k,&W,lwork,&work,PetscMax(1,3*m-2),&rwork);
    522: #else
    523:   PetscCallBLAS("LAPACKsyev",LAPACKsyev_("V","L",&n,&adummy,&ld,&dummy,&a,&lwork,&info));
    524:   PetscBLASIntCast((PetscInt)a,&lwork);
    525:   PetscMalloc4(m,&eig,m*m,&Q,m*k,&W,lwork,&work);
    526: #endif

    528:   /* compute eigendecomposition */
    529:   for (j=0;j<n;j++) for (i=j;i<n;i++) Q[i+j*ld] = As[i+j*ld];
    530: #if defined(PETSC_USE_COMPLEX)
    531:   PetscCallBLAS("LAPACKsyev",LAPACKsyev_("V","L",&n,Q,&ld,eig,work,&lwork,rwork,&info));
    532: #else
    533:   PetscCallBLAS("LAPACKsyev",LAPACKsyev_("V","L",&n,Q,&ld,eig,work,&lwork,&info));
    534: #endif
    535:   SlepcCheckLapackInfo("syev",info);

    537:   /* W = f(Lambda)*Q' */
    538:   for (i=0;i<n;i++) {
    539:     x = fn->alpha*eig[i];
    540:     PetscUseTypeMethod(fn,evaluatefunction,x,&y);  /* y = f(x) */
    541:     for (j=0;j<k;j++) W[i+j*ld] = PetscConj(Q[j+i*ld])*fn->beta*y;
    542:   }
    543:   /* Bs = Q*W */
    544:   PetscCallBLAS("BLASgemm",BLASgemm_("N","N",&n,&k,&n,&one,Q,&ld,W,&ld,&zero,Bs,&ld));
    545: #if defined(PETSC_USE_COMPLEX)
    546:   PetscFree5(eig,Q,W,work,rwork);
    547: #else
    548:   PetscFree4(eig,Q,W,work);
    549: #endif
    550:   PetscLogFlops(9.0*n*n*n+2.0*n*n*n);
    551:   return 0;
    552: }

    554: /*
    555:    FNEvaluateFunctionMat_Sym_Default - given a symmetric matrix A,
    556:    compute the matrix function as f(A)=Q*f(D)*Q' where the spectral
    557:    decomposition of A is A=Q*D*Q'
    558: */
    559: static PetscErrorCode FNEvaluateFunctionMat_Sym_Default(FN fn,Mat A,Mat B)
    560: {
    561:   PetscInt          m;
    562:   const PetscScalar *As;
    563:   PetscScalar       *Bs;

    565:   MatDenseGetArrayRead(A,&As);
    566:   MatDenseGetArray(B,&Bs);
    567:   MatGetSize(A,&m,NULL);
    568:   FNEvaluateFunctionMat_Sym_Private(fn,As,Bs,m,PETSC_FALSE);
    569:   MatDenseRestoreArrayRead(A,&As);
    570:   MatDenseRestoreArray(B,&Bs);
    571:   return 0;
    572: }

    574: PetscErrorCode FNEvaluateFunctionMat_Basic(FN fn,Mat A,Mat F)
    575: {
    576:   PetscBool iscuda;

    578:   PetscObjectTypeCompare((PetscObject)A,MATSEQDENSECUDA,&iscuda);
    579:   if (iscuda && !fn->ops->evaluatefunctionmatcuda[fn->method]) PetscInfo(fn,"The method %" PetscInt_FMT " is not implemented for CUDA, falling back to CPU version\n",fn->method);
    580:   if (iscuda && fn->ops->evaluatefunctionmatcuda[fn->method]) PetscUseTypeMethod(fn,evaluatefunctionmatcuda[fn->method],A,F);
    581:   else if (fn->ops->evaluatefunctionmat[fn->method]) PetscUseTypeMethod(fn,evaluatefunctionmat[fn->method],A,F);
    582:   else {
    585:   }
    586:   return 0;
    587: }

    589: PetscErrorCode FNEvaluateFunctionMat_Private(FN fn,Mat A,Mat B,PetscBool sync)
    590: {
    591:   PetscBool      set,flg,symm=PETSC_FALSE,iscuda,hasspecificmeth;
    592:   PetscInt       m,n;
    593:   PetscMPIInt    size,rank;
    594:   PetscScalar    *pF;
    595:   Mat            M,F;

    597:   /* destination matrix */
    598:   F = B?B:A;

    600:   /* check symmetry of A */
    601:   MatIsHermitianKnown(A,&set,&flg);
    602:   symm = set? flg: PETSC_FALSE;

    604:   MPI_Comm_size(PetscObjectComm((PetscObject)fn),&size);
    605:   MPI_Comm_rank(PetscObjectComm((PetscObject)fn),&rank);
    606:   if (size==1 || fn->pmode==FN_PARALLEL_REDUNDANT || (fn->pmode==FN_PARALLEL_SYNCHRONIZED && !rank)) {
    607:     PetscFPTrapPush(PETSC_FP_TRAP_OFF);
    608:     PetscObjectTypeCompare((PetscObject)A,MATSEQDENSECUDA,&iscuda);
    609:     hasspecificmeth = ((iscuda && fn->ops->evaluatefunctionmatcuda[fn->method]) || (!iscuda && fn->method && fn->ops->evaluatefunctionmat[fn->method]))? PETSC_TRUE: PETSC_FALSE;
    610:     if (!hasspecificmeth && symm && !fn->method) {  /* prefer diagonalization */
    611:       PetscInfo(fn,"Computing matrix function via diagonalization\n");
    612:       FNEvaluateFunctionMat_Sym_Default(fn,A,F);
    613:     } else {
    614:       /* scale argument */
    615:       if (fn->alpha!=(PetscScalar)1.0) {
    616:         FN_AllocateWorkMat(fn,A,&M);
    617:         MatScale(M,fn->alpha);
    618:       } else M = A;
    619:       FNEvaluateFunctionMat_Basic(fn,M,F);
    620:       if (fn->alpha!=(PetscScalar)1.0) FN_FreeWorkMat(fn,&M);
    621:       /* scale result */
    622:       MatScale(F,fn->beta);
    623:     }
    624:     PetscFPTrapPop();
    625:   }
    626:   if (size>1 && fn->pmode==FN_PARALLEL_SYNCHRONIZED && sync) {  /* synchronize */
    627:     MatGetSize(A,&m,&n);
    628:     MatDenseGetArray(F,&pF);
    629:     MPI_Bcast(pF,n*n,MPIU_SCALAR,0,PetscObjectComm((PetscObject)fn));
    630:     MatDenseRestoreArray(F,&pF);
    631:   }
    632:   return 0;
    633: }

    635: /*@
    636:    FNEvaluateFunctionMat - Computes the value of the function f(A) for a given
    637:    matrix A, where the result is also a matrix.

    639:    Logically Collective on fn

    641:    Input Parameters:
    642: +  fn - the math function context
    643: -  A  - matrix on which the function must be evaluated

    645:    Output Parameter:
    646: .  B  - (optional) matrix resulting from evaluating f(A)

    648:    Notes:
    649:    Matrix A must be a square sequential dense Mat, with all entries equal on
    650:    all processes (otherwise each process will compute different results).
    651:    If matrix B is provided, it must also be a square sequential dense Mat, and
    652:    both matrices must have the same dimensions. If B is NULL (or B=A) then the
    653:    function will perform an in-place computation, overwriting A with f(A).

    655:    If A is known to be real symmetric or complex Hermitian then it is
    656:    recommended to set the appropriate flag with MatSetOption(), because
    657:    symmetry can sometimes be exploited by the algorithm.

    659:    Scaling factors are taken into account, so the actual function evaluation
    660:    will return beta*f(alpha*A).

    662:    Level: advanced

    664: .seealso: FNEvaluateFunction(), FNEvaluateFunctionMatVec(), FNSetMethod()
    665: @*/
    666: PetscErrorCode FNEvaluateFunctionMat(FN fn,Mat A,Mat B)
    667: {
    668:   PetscBool      inplace=PETSC_FALSE;
    669:   PetscInt       m,n,n1;
    670:   MatType        type;

    676:   if (B) {
    679:   } else inplace = PETSC_TRUE;
    681:   MatGetSize(A,&m,&n);
    683:   if (!inplace) {
    684:     MatGetType(A,&type);
    686:     n1 = n;
    687:     MatGetSize(B,&m,&n);
    690:   }

    692:   /* evaluate matrix function */
    693:   PetscLogEventBegin(FN_Evaluate,fn,0,0,0);
    694:   FNEvaluateFunctionMat_Private(fn,A,B,PETSC_TRUE);
    695:   PetscLogEventEnd(FN_Evaluate,fn,0,0,0);
    696:   return 0;
    697: }

    699: /*
    700:    FNEvaluateFunctionMatVec_Default - computes the full matrix f(A)
    701:    and then copies the first column.
    702: */
    703: static PetscErrorCode FNEvaluateFunctionMatVec_Default(FN fn,Mat A,Vec v)
    704: {
    705:   Mat            F;

    707:   FN_AllocateWorkMat(fn,A,&F);
    708:   FNEvaluateFunctionMat_Basic(fn,A,F);
    709:   MatGetColumnVector(F,v,0);
    710:   FN_FreeWorkMat(fn,&F);
    711:   return 0;
    712: }

    714: /*
    715:    FNEvaluateFunctionMatVec_Sym_Default - given a symmetric matrix A,
    716:    compute the matrix function as f(A)=Q*f(D)*Q' where the spectral
    717:    decomposition of A is A=Q*D*Q'. Only the first column is computed.
    718: */
    719: static PetscErrorCode FNEvaluateFunctionMatVec_Sym_Default(FN fn,Mat A,Vec v)
    720: {
    721:   PetscInt          m;
    722:   const PetscScalar *As;
    723:   PetscScalar       *vs;

    725:   MatDenseGetArrayRead(A,&As);
    726:   VecGetArray(v,&vs);
    727:   MatGetSize(A,&m,NULL);
    728:   FNEvaluateFunctionMat_Sym_Private(fn,As,vs,m,PETSC_TRUE);
    729:   MatDenseRestoreArrayRead(A,&As);
    730:   VecRestoreArray(v,&vs);
    731:   return 0;
    732: }

    734: PetscErrorCode FNEvaluateFunctionMatVec_Private(FN fn,Mat A,Vec v,PetscBool sync)
    735: {
    736:   PetscBool      set,flg,symm=PETSC_FALSE,iscuda,hasspecificmeth;
    737:   PetscInt       m,n;
    738:   Mat            M;
    739:   PetscMPIInt    size,rank;
    740:   PetscScalar    *pv;

    742:   /* check symmetry of A */
    743:   MatIsHermitianKnown(A,&set,&flg);
    744:   symm = set? flg: PETSC_FALSE;

    746:   /* evaluate matrix function */
    747:   MPI_Comm_size(PetscObjectComm((PetscObject)fn),&size);
    748:   MPI_Comm_rank(PetscObjectComm((PetscObject)fn),&rank);
    749:   if (size==1 || fn->pmode==FN_PARALLEL_REDUNDANT || (fn->pmode==FN_PARALLEL_SYNCHRONIZED && !rank)) {
    750:     PetscFPTrapPush(PETSC_FP_TRAP_OFF);
    751:     PetscObjectTypeCompare((PetscObject)A,MATSEQDENSECUDA,&iscuda);
    752:     hasspecificmeth = ((iscuda && fn->ops->evaluatefunctionmatcuda[fn->method]) || (!iscuda && fn->method && fn->ops->evaluatefunctionmat[fn->method]))? PETSC_TRUE: PETSC_FALSE;
    753:     if (!hasspecificmeth && symm && !fn->method) {  /* prefer diagonalization */
    754:       PetscInfo(fn,"Computing matrix function via diagonalization\n");
    755:       FNEvaluateFunctionMatVec_Sym_Default(fn,A,v);
    756:     } else {
    757:       /* scale argument */
    758:       if (fn->alpha!=(PetscScalar)1.0) {
    759:         FN_AllocateWorkMat(fn,A,&M);
    760:         MatScale(M,fn->alpha);
    761:       } else M = A;
    762:       if (iscuda && fn->ops->evaluatefunctionmatveccuda[fn->method]) PetscUseTypeMethod(fn,evaluatefunctionmatveccuda[fn->method],M,v);
    763:       else if (fn->ops->evaluatefunctionmatvec[fn->method]) PetscUseTypeMethod(fn,evaluatefunctionmatvec[fn->method],M,v);
    764:       else FNEvaluateFunctionMatVec_Default(fn,M,v);
    765:       if (fn->alpha!=(PetscScalar)1.0) FN_FreeWorkMat(fn,&M);
    766:       /* scale result */
    767:       VecScale(v,fn->beta);
    768:     }
    769:     PetscFPTrapPop();
    770:   }

    772:   /* synchronize */
    773:   if (size>1 && fn->pmode==FN_PARALLEL_SYNCHRONIZED && sync) {
    774:     MatGetSize(A,&m,&n);
    775:     VecGetArray(v,&pv);
    776:     MPI_Bcast(pv,n,MPIU_SCALAR,0,PetscObjectComm((PetscObject)fn));
    777:     VecRestoreArray(v,&pv);
    778:   }
    779:   return 0;
    780: }

    782: /*@
    783:    FNEvaluateFunctionMatVec - Computes the first column of the matrix f(A)
    784:    for a given matrix A.

    786:    Logically Collective on fn

    788:    Input Parameters:
    789: +  fn - the math function context
    790: -  A  - matrix on which the function must be evaluated

    792:    Output Parameter:
    793: .  v  - vector to hold the first column of f(A)

    795:    Notes:
    796:    This operation is similar to FNEvaluateFunctionMat() but returns only
    797:    the first column of f(A), hence saving computations in most cases.

    799:    Level: advanced

    801: .seealso: FNEvaluateFunction(), FNEvaluateFunctionMat(), FNSetMethod()
    802: @*/
    803: PetscErrorCode FNEvaluateFunctionMatVec(FN fn,Mat A,Vec v)
    804: {
    805:   PetscInt       m,n;
    806:   PetscBool      iscuda;

    815:   MatGetSize(A,&m,&n);
    817:   PetscObjectTypeCompare((PetscObject)A,MATSEQDENSECUDA,&iscuda);
    819:   VecGetSize(v,&m);
    821:   PetscLogEventBegin(FN_Evaluate,fn,0,0,0);
    822:   FNEvaluateFunctionMatVec_Private(fn,A,v,PETSC_TRUE);
    823:   PetscLogEventEnd(FN_Evaluate,fn,0,0,0);
    824:   return 0;
    825: }

    827: /*@
    828:    FNSetFromOptions - Sets FN options from the options database.

    830:    Collective on fn

    832:    Input Parameters:
    833: .  fn - the math function context

    835:    Notes:
    836:    To see all options, run your program with the -help option.

    838:    Level: beginner

    840: .seealso: FNSetOptionsPrefix()
    841: @*/
    842: PetscErrorCode FNSetFromOptions(FN fn)
    843: {
    844:   char           type[256];
    845:   PetscScalar    array[2];
    846:   PetscInt       k,meth;
    847:   PetscBool      flg;
    848:   FNParallelType pmode;

    851:   FNRegisterAll();
    852:   PetscObjectOptionsBegin((PetscObject)fn);
    853:     PetscOptionsFList("-fn_type","Math function type","FNSetType",FNList,(char*)(((PetscObject)fn)->type_name?((PetscObject)fn)->type_name:FNRATIONAL),type,sizeof(type),&flg);
    854:     if (flg) FNSetType(fn,type);
    855:     else if (!((PetscObject)fn)->type_name) FNSetType(fn,FNRATIONAL);

    857:     k = 2;
    858:     array[0] = 0.0; array[1] = 0.0;
    859:     PetscOptionsScalarArray("-fn_scale","Scale factors (one or two scalar values separated with a comma without spaces)","FNSetScale",array,&k,&flg);
    860:     if (flg) {
    861:       if (k<2) array[1] = 1.0;
    862:       FNSetScale(fn,array[0],array[1]);
    863:     }

    865:     PetscOptionsInt("-fn_method","Method to be used for computing matrix functions","FNSetMethod",fn->method,&meth,&flg);
    866:     if (flg) FNSetMethod(fn,meth);

    868:     PetscOptionsEnum("-fn_parallel","Operation mode in parallel runs","FNSetParallel",FNParallelTypes,(PetscEnum)fn->pmode,(PetscEnum*)&pmode,&flg);
    869:     if (flg) FNSetParallel(fn,pmode);

    871:     PetscTryTypeMethod(fn,setfromoptions,PetscOptionsObject);
    872:     PetscObjectProcessOptionsHandlers((PetscObject)fn,PetscOptionsObject);
    873:   PetscOptionsEnd();
    874:   return 0;
    875: }

    877: /*@C
    878:    FNView - Prints the FN data structure.

    880:    Collective on fn

    882:    Input Parameters:
    883: +  fn - the math function context
    884: -  viewer - optional visualization context

    886:    Note:
    887:    The available visualization contexts include
    888: +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
    889: -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
    890:          output where only the first processor opens
    891:          the file.  All other processors send their
    892:          data to the first processor to print.

    894:    The user can open an alternative visualization context with
    895:    PetscViewerASCIIOpen() - output to a specified file.

    897:    Level: beginner

    899: .seealso: FNCreate()
    900: @*/
    901: PetscErrorCode FNView(FN fn,PetscViewer viewer)
    902: {
    903:   PetscBool      isascii;
    904:   PetscMPIInt    size;

    907:   if (!viewer) PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)fn),&viewer);
    910:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isascii);
    911:   if (isascii) {
    912:     PetscObjectPrintClassNamePrefixType((PetscObject)fn,viewer);
    913:     MPI_Comm_size(PetscObjectComm((PetscObject)fn),&size);
    914:     if (size>1) PetscViewerASCIIPrintf(viewer,"  parallel operation mode: %s\n",FNParallelTypes[fn->pmode]);
    915:     PetscViewerASCIIPushTab(viewer);
    916:     PetscTryTypeMethod(fn,view,viewer);
    917:     PetscViewerASCIIPopTab(viewer);
    918:   }
    919:   return 0;
    920: }

    922: /*@C
    923:    FNViewFromOptions - View from options

    925:    Collective on FN

    927:    Input Parameters:
    928: +  fn   - the math function context
    929: .  obj  - optional object
    930: -  name - command line option

    932:    Level: intermediate

    934: .seealso: FNView(), FNCreate()
    935: @*/
    936: PetscErrorCode FNViewFromOptions(FN fn,PetscObject obj,const char name[])
    937: {
    939:   PetscObjectViewFromOptions((PetscObject)fn,obj,name);
    940:   return 0;
    941: }

    943: /*@
    944:    FNDuplicate - Duplicates a math function, copying all parameters, possibly with a
    945:    different communicator.

    947:    Collective on fn

    949:    Input Parameters:
    950: +  fn   - the math function context
    951: -  comm - MPI communicator

    953:    Output Parameter:
    954: .  newfn - location to put the new FN context

    956:    Note:
    957:    In order to use the same MPI communicator as in the original object,
    958:    use PetscObjectComm((PetscObject)fn).

    960:    Level: developer

    962: .seealso: FNCreate()
    963: @*/
    964: PetscErrorCode FNDuplicate(FN fn,MPI_Comm comm,FN *newfn)
    965: {
    966:   FNType         type;
    967:   PetscScalar    alpha,beta;
    968:   PetscInt       meth;
    969:   FNParallelType ptype;

    974:   FNCreate(comm,newfn);
    975:   FNGetType(fn,&type);
    976:   FNSetType(*newfn,type);
    977:   FNGetScale(fn,&alpha,&beta);
    978:   FNSetScale(*newfn,alpha,beta);
    979:   FNGetMethod(fn,&meth);
    980:   FNSetMethod(*newfn,meth);
    981:   FNGetParallel(fn,&ptype);
    982:   FNSetParallel(*newfn,ptype);
    983:   PetscTryTypeMethod(fn,duplicate,comm,newfn);
    984:   return 0;
    985: }

    987: /*@C
    988:    FNDestroy - Destroys FN context that was created with FNCreate().

    990:    Collective on fn

    992:    Input Parameter:
    993: .  fn - the math function context

    995:    Level: beginner

    997: .seealso: FNCreate()
    998: @*/
    999: PetscErrorCode FNDestroy(FN *fn)
    1000: {
    1001:   PetscInt       i;

    1003:   if (!*fn) return 0;
    1005:   if (--((PetscObject)(*fn))->refct > 0) { *fn = NULL; return 0; }
    1006:   PetscTryTypeMethod(*fn,destroy);
    1007:   for (i=0;i<(*fn)->nw;i++) MatDestroy(&(*fn)->W[i]);
    1008:   PetscHeaderDestroy(fn);
    1009:   return 0;
    1010: }

    1012: /*@C
    1013:    FNRegister - Adds a mathematical function to the FN package.

    1015:    Not collective

    1017:    Input Parameters:
    1018: +  name - name of a new user-defined FN
    1019: -  function - routine to create context

    1021:    Notes:
    1022:    FNRegister() may be called multiple times to add several user-defined functions.

    1024:    Level: advanced

    1026: .seealso: FNRegisterAll()
    1027: @*/
    1028: PetscErrorCode FNRegister(const char *name,PetscErrorCode (*function)(FN))
    1029: {
    1030:   FNInitializePackage();
    1031:   PetscFunctionListAdd(&FNList,name,function);
    1032:   return 0;
    1033: }