Date: 2024-10-28T09:13:16+00:00

Actual source code: evsl.c
slepc-3.22.1 2024-10-28
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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:    This file implements a wrapper to eigensolvers in EVSL.
     12: */

     14: #include <slepc/private/epsimpl.h>
     15: #include <evsl.h>

     17: #define PetscCallEVSL(func, ...) do {                                                   \
     18:     PetscStackPushExternal(PetscStringize(func));                                                      \
     19:     int evsl_ierr_ = func(__VA_ARGS__);                                              \
     20:     PetscStackPop;                                                                             \
     21:     PetscCheck(!evsl_ierr_,PETSC_COMM_SELF,PETSC_ERR_LIB,"Error calling %s: error code %d",PetscStringize(func(__VA_ARGS__)),evsl_ierr_); \
     22:   } while (0)

     24: typedef struct {
     25:   PetscBool         initialized;
     26:   Mat               A;           /* problem matrix */
     27:   Vec               x,y;         /* auxiliary vectors */
     28:   PetscReal         *sli;        /* slice bounds */
     29:   PetscInt          nev;         /* approximate number of wanted eigenvalues in each slice */
     30:   PetscLayout       map;         /* used to distribute slices among MPI processes */
     31:   PetscBool         estimrange;  /* the filter range was not set by the user */
     32:   /* user parameters */
     33:   PetscInt          nslices;     /* number of slices */
     34:   PetscReal         lmin,lmax;   /* numerical range (min and max eigenvalue) */
     35:   EPSEVSLDOSMethod  dos;         /* DOS method, either KPM or Lanczos */
     36:   PetscInt          nvec;        /* number of sample vectors used for DOS */
     37:   PetscInt          deg;         /* polynomial degree used for DOS (KPM only) */
     38:   PetscInt          steps;       /* number of Lanczos steps used for DOS (Lanczos only) */
     39:   PetscInt          npoints;     /* number of sample points used for DOS (Lanczos only) */
     40:   PetscInt          max_deg;     /* maximum degree allowed for the polynomial */
     41:   PetscReal         thresh;      /* threshold for accepting polynomial */
     42:   EPSEVSLDamping    damping;     /* type of damping (for polynomial and for DOS-KPM) */
     43: } EPS_EVSL;

     45: static void AMatvec_EVSL(double *xa,double *ya,void *data)
     46: {
     47:   EPS_EVSL       *ctx = (EPS_EVSL*)data;
     48:   Vec            x = ctx->x,y = ctx->y;
     49:   Mat            A = ctx->A;

     51:   PetscFunctionBegin;
     52:   PetscCallAbort(PetscObjectComm((PetscObject)A),VecPlaceArray(x,(PetscScalar*)xa));
     53:   PetscCallAbort(PetscObjectComm((PetscObject)A),VecPlaceArray(y,(PetscScalar*)ya));
     54:   PetscCallAbort(PetscObjectComm((PetscObject)A),MatMult(A,x,y));
     55:   PetscCallAbort(PetscObjectComm((PetscObject)A),VecResetArray(x));
     56:   PetscCallAbort(PetscObjectComm((PetscObject)A),VecResetArray(y));
     57:   PetscFunctionReturnVoid();
     58: }

     60: static PetscErrorCode EPSSetUp_EVSL(EPS eps)
     61: {
     62:   EPS_EVSL       *ctx = (EPS_EVSL*)eps->data;
     63:   PetscMPIInt    size,rank;
     64:   PetscBool      isshift;
     65:   PetscScalar    *vinit;
     66:   PetscReal      *mu,ecount,xintv[4],*xdos,*ydos;
     67:   Vec            v0;
     68:   Mat            A;
     69:   PetscRandom    rnd;

     71:   PetscFunctionBegin;
     72:   EPSCheckStandard(eps);
     73:   EPSCheckHermitian(eps);
     74:   EPSCheckNotStructured(eps);
     75:   PetscCall(PetscObjectTypeCompare((PetscObject)eps->st,STSHIFT,&isshift));
     76:   PetscCheck(isshift,PetscObjectComm((PetscObject)eps),PETSC_ERR_SUP,"This solver does not support spectral transformations");

     78:   if (ctx->initialized) EVSLFinish();
     79:   EVSLStart();
     80:   ctx->initialized=PETSC_TRUE;

     82:   /* get number of slices per process */
     83:   PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)eps),&size));
     84:   PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)eps),&rank));
     85:   if (!ctx->nslices) ctx->nslices = size;
     86:   PetscCall(PetscLayoutDestroy(&ctx->map));
     87:   PetscCall(PetscLayoutCreateFromSizes(PetscObjectComm((PetscObject)eps),PETSC_DECIDE,ctx->nslices,1,&ctx->map));

     89:   /* get matrix and prepare auxiliary vectors */
     90:   PetscCall(MatDestroy(&ctx->A));
     91:   PetscCall(STGetMatrix(eps->st,0,&A));
     92:   if (size==1) {
     93:     PetscCall(PetscObjectReference((PetscObject)A));
     94:     ctx->A = A;
     95:   } else PetscCall(MatCreateRedundantMatrix(A,0,PETSC_COMM_SELF,MAT_INITIAL_MATRIX,&ctx->A));
     96:   SetAMatvec(eps->n,&AMatvec_EVSL,(void*)ctx);
     97:   if (!ctx->x) PetscCall(MatCreateVecsEmpty(ctx->A,&ctx->x,&ctx->y));
     98:   EPSCheckUnsupported(eps,EPS_FEATURE_ARBITRARY | EPS_FEATURE_REGION | EPS_FEATURE_STOPPING);
     99:   EPSCheckIgnored(eps,EPS_FEATURE_EXTRACTION | EPS_FEATURE_CONVERGENCE);

    101:   if (!eps->which) eps->which=EPS_ALL;
    102:   PetscCheck(eps->which==EPS_ALL && eps->inta!=eps->intb,PetscObjectComm((PetscObject)eps),PETSC_ERR_SUP,"This solver requires setting an interval with EPSSetInterval()");

    104:   /* estimate numerical range */
    105:   if (ctx->estimrange || ctx->lmin == PETSC_MIN_REAL || ctx->lmax == PETSC_MAX_REAL) {
    106:     PetscCall(MatCreateVecs(ctx->A,&v0,NULL));
    107:     if (!eps->V) PetscCall(EPSGetBV(eps,&eps->V));
    108:     PetscCall(BVGetRandomContext(eps->V,&rnd));
    109:     PetscCall(VecSetRandom(v0,rnd));
    110:     PetscCall(VecGetArray(v0,&vinit));
    111:     PetscCallEVSL(LanTrbounds,50,200,eps->tol,vinit,1,&ctx->lmin,&ctx->lmax,NULL);
    112:     PetscCall(VecRestoreArray(v0,&vinit));
    113:     PetscCall(VecDestroy(&v0));
    114:     ctx->estimrange = PETSC_TRUE;   /* estimate if called again with another matrix */
    115:   }
    116:   PetscCheck(ctx->lmin<=eps->inta && ctx->lmax>=eps->intb,PetscObjectComm((PetscObject)eps),PETSC_ERR_SUP,"The requested interval [%g,%g] must be contained in the numerical range [%g,%g]",(double)eps->inta,(double)eps->intb,(double)ctx->lmin,(double)ctx->lmax);
    117:   xintv[0] = eps->inta;
    118:   xintv[1] = eps->intb;
    119:   xintv[2] = ctx->lmin;
    120:   xintv[3] = ctx->lmax;

    122:   /* estimate number of eigenvalues in the interval */
    123:   switch (ctx->dos) {
    124:     case EPS_EVSL_DOS_KPM:
    125:       PetscCall(PetscMalloc1(ctx->deg+1,&mu));
    126:       if (!rank) PetscCallEVSL(kpmdos,ctx->deg,(int)ctx->damping,ctx->nvec,xintv,mu,&ecount);
    127:       PetscCallMPI(MPI_Bcast(mu,ctx->deg+1,MPIU_REAL,0,PetscObjectComm((PetscObject)eps)));
    128:       break;
    129:     case EPS_EVSL_DOS_LANCZOS:
    130:       PetscCall(PetscMalloc2(ctx->npoints,&xdos,ctx->npoints,&ydos));
    131:       if (!rank) PetscCallEVSL(LanDos,ctx->nvec,PetscMin(ctx->steps,eps->n/2),ctx->npoints,xdos,ydos,&ecount,xintv);
    132:       PetscCallMPI(MPI_Bcast(xdos,ctx->npoints,MPIU_REAL,0,PetscObjectComm((PetscObject)eps)));
    133:       PetscCallMPI(MPI_Bcast(ydos,ctx->npoints,MPIU_REAL,0,PetscObjectComm((PetscObject)eps)));
    134:       break;
    135:     default:
    136:       SETERRQ(PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"Invalid DOS method");
    137:   }
    138:   PetscCallMPI(MPI_Bcast(&ecount,1,MPIU_REAL,0,PetscObjectComm((PetscObject)eps)));

    140:   PetscCall(PetscInfo(eps,"Estimated eigenvalue count in the interval: %g\n",ecount));
    141:   eps->ncv = (PetscInt)PetscCeilReal(1.5*ecount);

    143:   /* slice the spectrum */
    144:   PetscCall(PetscFree(ctx->sli));
    145:   PetscCall(PetscMalloc1(ctx->nslices+1,&ctx->sli));
    146:   if (ctx->dos == EPS_EVSL_DOS_KPM) {
    147:     PetscCallEVSL(spslicer,ctx->sli,mu,ctx->deg,xintv,ctx->nslices,10*(PetscInt)ecount);
    148:     PetscCall(PetscFree(mu));
    149:   } else if (ctx->dos == EPS_EVSL_DOS_LANCZOS) {
    150:     spslicer2(xdos,ydos,ctx->nslices,ctx->npoints,ctx->sli);
    151:     PetscCall(PetscFree2(xdos,ydos));
    152:   }

    154:   /* approximate number of eigenvalues wanted in each slice */
    155:   ctx->nev = (PetscInt)(1.0 + ecount/(PetscReal)ctx->nslices) + 2;

    157:   if (eps->mpd!=PETSC_DETERMINE) PetscCall(PetscInfo(eps,"Warning: parameter mpd ignored\n"));
    158:   if (eps->max_it==PETSC_DETERMINE) eps->max_it = 1;
    159:   PetscCall(EPSAllocateSolution(eps,0));
    160:   PetscFunctionReturn(PETSC_SUCCESS);
    161: }

    163: static PetscErrorCode EPSSolve_EVSL(EPS eps)
    164: {
    165:   EPS_EVSL       *ctx = (EPS_EVSL*)eps->data;
    166:   PetscInt       i,j,k=0,sl,mlan,nevout,*ind,nevmax,rstart,rend,*nevloc,*disp,N;
    167:   PetscReal      *res,xintv[4],*errest;
    168:   PetscScalar    *lam,*X,*Y,*vinit,*eigr;
    169:   PetscMPIInt    size,rank;
    170:   PetscRandom    rnd;
    171:   Vec            v,w,v0,x;
    172:   VecScatter     vs;
    173:   IS             is;
    174:   polparams      pol;

    176:   PetscFunctionBegin;
    177:   PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)eps),&size));
    178:   PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)eps),&rank));
    179:   PetscCall(PetscLayoutGetRange(ctx->map,&rstart,&rend));
    180:   nevmax = (rend-rstart)*ctx->nev;
    181:   PetscCall(MatCreateVecs(ctx->A,&v0,NULL));
    182:   PetscCall(BVGetRandomContext(eps->V,&rnd));
    183:   PetscCall(VecSetRandom(v0,rnd));
    184:   PetscCall(VecGetArray(v0,&vinit));
    185:   PetscCall(PetscMalloc5(size,&nevloc,size+1,&disp,nevmax,&eigr,nevmax,&errest,nevmax*eps->n,&X));
    186:   mlan = PetscMin(PetscMax(5*ctx->nev,300),eps->n);
    187:   for (sl=rstart; sl<rend; sl++) {
    188:     xintv[0] = ctx->sli[sl];
    189:     xintv[1] = ctx->sli[sl+1];
    190:     xintv[2] = ctx->lmin;
    191:     xintv[3] = ctx->lmax;
    192:     PetscCall(PetscInfo(ctx->A,"Subinterval %" PetscInt_FMT ": [%.4e, %.4e]\n",sl+1,xintv[0],xintv[1]));
    193:     set_pol_def(&pol);
    194:     pol.max_deg    = ctx->max_deg;
    195:     pol.damping    = (int)ctx->damping;
    196:     pol.thresh_int = ctx->thresh;
    197:     find_pol(xintv,&pol);
    198:     PetscCall(PetscInfo(ctx->A,"Polynomial [type = %" PetscInt_FMT "], deg %" PetscInt_FMT ", bar %e gam %e\n",pol.type,pol.deg,pol.bar,pol.gam));
    199:     PetscCallEVSL(ChebLanNr,xintv,mlan,eps->tol,vinit,&pol,&nevout,&lam,&Y,&res,NULL);
    200:     PetscCheck(k+nevout<=nevmax,PetscObjectComm((PetscObject)eps),PETSC_ERR_LIB,"Too low estimation of eigenvalue count, try modifying the sampling parameters");
    201:     free_pol(&pol);
    202:     PetscCall(PetscInfo(ctx->A,"Computed %" PetscInt_FMT " eigenvalues\n",nevout));
    203:     PetscCall(PetscMalloc1(nevout,&ind));
    204:     sort_double(nevout,lam,ind);
    205:     for (i=0;i<nevout;i++) {
    206:       eigr[i+k]   = lam[i];
    207:       errest[i+k] = res[ind[i]];
    208:       PetscCall(PetscArraycpy(X+(i+k)*eps->n,Y+ind[i]*eps->n,eps->n));
    209:     }
    210:     k += nevout;
    211:     if (lam) evsl_Free(lam);
    212:     if (Y)   evsl_Free_device(Y);
    213:     if (res) evsl_Free(res);
    214:     PetscCall(PetscFree(ind));
    215:   }
    216:   PetscCall(VecRestoreArray(v0,&vinit));
    217:   PetscCall(VecDestroy(&v0));

    219:   /* gather eigenvalues computed by each MPI process */
    220:   PetscCallMPI(MPI_Allgather(&k,1,MPIU_INT,nevloc,1,MPIU_INT,PetscObjectComm((PetscObject)eps)));
    221:   eps->nev = nevloc[0];
    222:   disp[0]  = 0;
    223:   for (i=1;i<size;i++) {
    224:     eps->nev += nevloc[i];
    225:     disp[i]   = disp[i-1]+nevloc[i-1];
    226:   }
    227:   disp[size] = disp[size-1]+nevloc[size-1];
    228:   PetscCheck(eps->nev<=eps->ncv,PetscObjectComm((PetscObject)eps),PETSC_ERR_LIB,"Too low estimation of eigenvalue count, try modifying the sampling parameters");
    229:   PetscCallMPI(MPI_Allgatherv(eigr,k,MPIU_SCALAR,eps->eigr,nevloc,disp,MPIU_SCALAR,PetscObjectComm((PetscObject)eps)));
    230:   PetscCallMPI(MPI_Allgatherv(errest,k,MPIU_REAL,eps->errest,nevloc,disp,MPIU_REAL,PetscObjectComm((PetscObject)eps)));
    231:   eps->nconv  = eps->nev;
    232:   eps->its    = 1;
    233:   eps->reason = EPS_CONVERGED_TOL;

    235:   /* scatter computed eigenvectors and store them in eps->V */
    236:   PetscCall(BVCreateVec(eps->V,&w));
    237:   for (i=0;i<size;i++) {
    238:     N = (rank==i)? eps->n: 0;
    239:     PetscCall(VecCreateSeq(PETSC_COMM_SELF,N,&x));
    240:     PetscCall(VecSetFromOptions(x));
    241:     PetscCall(ISCreateStride(PETSC_COMM_SELF,N,0,1,&is));
    242:     PetscCall(VecScatterCreate(x,is,w,is,&vs));
    243:     PetscCall(ISDestroy(&is));
    244:     for (j=disp[i];j<disp[i+1];j++) {
    245:       PetscCall(BVGetColumn(eps->V,j,&v));
    246:       if (rank==i) PetscCall(VecPlaceArray(x,X+(j-disp[i])*eps->n));
    247:       PetscCall(VecScatterBegin(vs,x,v,INSERT_VALUES,SCATTER_FORWARD));
    248:       PetscCall(VecScatterEnd(vs,x,v,INSERT_VALUES,SCATTER_FORWARD));
    249:       if (rank==i) PetscCall(VecResetArray(x));
    250:       PetscCall(BVRestoreColumn(eps->V,j,&v));
    251:     }
    252:     PetscCall(VecScatterDestroy(&vs));
    253:     PetscCall(VecDestroy(&x));
    254:   }
    255:   PetscCall(VecDestroy(&w));
    256:   PetscCall(PetscFree5(nevloc,disp,eigr,errest,X));
    257:   PetscFunctionReturn(PETSC_SUCCESS);
    258: }

    260: static PetscErrorCode EPSEVSLSetSlices_EVSL(EPS eps,PetscInt nslices)
    261: {
    262:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    264:   PetscFunctionBegin;
    265:   if (nslices == PETSC_DECIDE || nslices == PETSC_DEFAULT) nslices = 0;
    266:   else PetscCheck(nslices>0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"Number of slices must be 1 at least");
    267:   if (ctx->nslices != nslices) {
    268:     ctx->nslices = nslices;
    269:     eps->state   = EPS_STATE_INITIAL;
    270:   }
    271:   PetscFunctionReturn(PETSC_SUCCESS);
    272: }

    274: /*@
    275:    EPSEVSLSetSlices - Set the number of slices in which the interval must be
    276:    subdivided.

    278:    Logically Collective

    280:    Input Parameters:
    281: +  eps     - the eigensolver context
    282: -  nslices - the number of slices

    284:    Options Database Key:
    285: .  -eps_evsl_slices <n> - set the number of slices to n

    287:    Notes:
    288:    By default, one slice per MPI process is used. Depending on the number of
    289:    eigenvalues, using more slices may be beneficial, but very narrow subintervals
    290:    imply higher polynomial degree.

    292:    Level: intermediate

    294: .seealso: EPSEVSLGetSlices()
    295: @*/
    296: PetscErrorCode EPSEVSLSetSlices(EPS eps,PetscInt nslices)
    297: {
    298:   PetscFunctionBegin;
    301:   PetscTryMethod(eps,"EPSEVSLSetSlices_C",(EPS,PetscInt),(eps,nslices));
    302:   PetscFunctionReturn(PETSC_SUCCESS);
    303: }

    305: static PetscErrorCode EPSEVSLGetSlices_EVSL(EPS eps,PetscInt *nslices)
    306: {
    307:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    309:   PetscFunctionBegin;
    310:   *nslices = ctx->nslices;
    311:   PetscFunctionReturn(PETSC_SUCCESS);
    312: }

    314: /*@
    315:    EPSEVSLGetSlices - Gets the number of slices in which the interval must be
    316:    subdivided.

    318:    Not Collective

    320:    Input Parameter:
    321: .  eps - the eigensolver context

    323:    Output Parameter:
    324: .  nslices - the number of slices

    326:    Level: intermediate

    328: .seealso: EPSEVSLSetSlices()
    329: @*/
    330: PetscErrorCode EPSEVSLGetSlices(EPS eps,PetscInt *nslices)
    331: {
    332:   PetscFunctionBegin;
    334:   PetscAssertPointer(nslices,2);
    335:   PetscUseMethod(eps,"EPSEVSLGetSlices_C",(EPS,PetscInt*),(eps,nslices));
    336:   PetscFunctionReturn(PETSC_SUCCESS);
    337: }

    339: static PetscErrorCode EPSEVSLSetRange_EVSL(EPS eps,PetscReal lmin,PetscReal lmax)
    340: {
    341:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    343:   PetscFunctionBegin;
    344:   PetscCheck(lmin<lmax,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_WRONG,"Badly defined interval, must be lmin<lmax");
    345:   if (ctx->lmin != lmin || ctx->lmax != lmax) {
    346:     ctx->lmin  = lmin;
    347:     ctx->lmax  = lmax;
    348:     eps->state = EPS_STATE_INITIAL;
    349:   }
    350:   PetscFunctionReturn(PETSC_SUCCESS);
    351: }

    353: /*@
    354:    EPSEVSLSetRange - Defines the numerical range (or field of values) of the problem,
    355:    that is, the interval containing all eigenvalues.

    357:    Logically Collective

    359:    Input Parameters:
    360: +  eps  - the eigensolver context
    361: .  lmin - left end of the interval
    362: -  lmax - right end of the interval

    364:    Options Database Key:
    365: .  -eps_evsl_range <a,b> - set [a,b] as the numerical range

    367:    Notes:
    368:    The filter will be most effective if the numerical range is tight, that is, lmin
    369:    and lmax are good approximations to the leftmost and rightmost eigenvalues,
    370:    respectively. If not set by the user, an approximation is computed internally.

    372:    The wanted computational interval specified via EPSSetInterval() must be
    373:    contained in the numerical range.

    375:    Level: intermediate

    377: .seealso: EPSEVSLGetRange(), EPSSetInterval()
    378: @*/
    379: PetscErrorCode EPSEVSLSetRange(EPS eps,PetscReal lmin,PetscReal lmax)
    380: {
    381:   PetscFunctionBegin;
    385:   PetscTryMethod(eps,"EPSEVSLSetRange_C",(EPS,PetscReal,PetscReal),(eps,lmin,lmax));
    386:   PetscFunctionReturn(PETSC_SUCCESS);
    387: }

    389: static PetscErrorCode EPSEVSLGetRange_EVSL(EPS eps,PetscReal *lmin,PetscReal *lmax)
    390: {
    391:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    393:   PetscFunctionBegin;
    394:   if (lmin) *lmin = ctx->lmin;
    395:   if (lmax) *lmax = ctx->lmax;
    396:   PetscFunctionReturn(PETSC_SUCCESS);
    397: }

    399: /*@
    400:    EPSEVSLGetRange - Gets the interval containing all eigenvalues.

    402:    Not Collective

    404:    Input Parameter:
    405: .  eps - the eigensolver context

    407:    Output Parameters:
    408: +  lmin - left end of the interval
    409: -  lmax - right end of the interval

    411:    Level: intermediate

    413: .seealso: EPSEVSLSetRange()
    414: @*/
    415: PetscErrorCode EPSEVSLGetRange(EPS eps,PetscReal *lmin,PetscReal *lmax)
    416: {
    417:   PetscFunctionBegin;
    419:   PetscUseMethod(eps,"EPSEVSLGetRange_C",(EPS,PetscReal*,PetscReal*),(eps,lmin,lmax));
    420:   PetscFunctionReturn(PETSC_SUCCESS);
    421: }

    423: static PetscErrorCode EPSEVSLSetDOSParameters_EVSL(EPS eps,EPSEVSLDOSMethod dos,PetscInt nvec,PetscInt deg,PetscInt steps,PetscInt npoints)
    424: {
    425:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    427:   PetscFunctionBegin;
    428:   ctx->dos = dos;
    429:   if (nvec == PETSC_DETERMINE) ctx->nvec = 80;
    430:   else if (nvec != PETSC_CURRENT) {
    431:     PetscCheck(nvec>0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"The nvec argument must be > 0");
    432:     ctx->nvec = nvec;
    433:   }
    434:   switch (dos) {
    435:     case EPS_EVSL_DOS_KPM:
    436:       if (deg == PETSC_DETERMINE) ctx->deg = 300;
    437:       else if (deg != PETSC_CURRENT) {
    438:         PetscCheck(deg>0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"The deg argument must be > 0");
    439:         ctx->deg = deg;
    440:       }
    441:       break;
    442:     case EPS_EVSL_DOS_LANCZOS:
    443:       if (steps == PETSC_DETERMINE) ctx->steps = 40;
    444:       else if (steps != PETSC_CURRENT) {
    445:         PetscCheck(steps>0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"The steps argument must be > 0");
    446:         ctx->steps = steps;
    447:       }
    448:       if (npoints == PETSC_DETERMINE) ctx->npoints = 200;
    449:       else if (npoints != PETSC_CURRENT) {
    450:         PetscCheck(npoints>0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"The npoints argument must be > 0");
    451:         ctx->npoints = npoints;
    452:       }
    453:       break;
    454:   }
    455:   eps->state = EPS_STATE_INITIAL;
    456:   PetscFunctionReturn(PETSC_SUCCESS);
    457: }

    459: /*@
    460:    EPSEVSLSetDOSParameters - Defines the parameters used for computing the
    461:    density of states (DOS) in the EVSL solver.

    463:    Logically Collective

    465:    Input Parameters:
    466: +  eps     - the eigensolver context
    467: .  dos     - DOS method, either KPM or Lanczos
    468: .  nvec    - number of sample vectors
    469: .  deg     - polynomial degree (KPM only)
    470: .  steps   - number of Lanczos steps (Lanczos only)
    471: -  npoints - number of sample points (Lanczos only)

    473:    Options Database Keys:
    474: +  -eps_evsl_dos_method <dos> - set the DOS method, either kpm or lanczos
    475: .  -eps_evsl_dos_nvec <n> - set the number of sample vectors
    476: .  -eps_evsl_dos_degree <n> - set the polynomial degree
    477: .  -eps_evsl_dos_steps <n> - set the number of Lanczos steps
    478: -  -eps_evsl_dos_npoints <n> - set the number of sample points

    480:    Notes:
    481:    The density of states (or spectral density) can be approximated with two
    482:    methods, kernel polynomial method (KPM) or Lanczos. Some parameters for
    483:    these methods can be set by the user with this function, with some of
    484:    them being relevant for one of the methods only.

    486:    For the integer argumens, you can use PETSC_CURRENT to keep the current
    487:    value, and PETSC_DETERMINE to set them to a reasonable default.

    489:    Level: intermediate

    491: .seealso: EPSEVSLGetDOSParameters()
    492: @*/
    493: PetscErrorCode EPSEVSLSetDOSParameters(EPS eps,EPSEVSLDOSMethod dos,PetscInt nvec,PetscInt deg,PetscInt steps,PetscInt npoints)
    494: {
    495:   PetscFunctionBegin;
    502:   PetscTryMethod(eps,"EPSEVSLSetDOSParameters_C",(EPS,EPSEVSLDOSMethod,PetscInt,PetscInt,PetscInt,PetscInt),(eps,dos,nvec,deg,steps,npoints));
    503:   PetscFunctionReturn(PETSC_SUCCESS);
    504: }

    506: static PetscErrorCode EPSEVSLGetDOSParameters_EVSL(EPS eps,EPSEVSLDOSMethod *dos,PetscInt *nvec,PetscInt *deg,PetscInt *steps,PetscInt *npoints)
    507: {
    508:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    510:   PetscFunctionBegin;
    511:   if (dos)     *dos     = ctx->dos;
    512:   if (nvec)    *nvec    = ctx->nvec;
    513:   if (deg)     *deg     = ctx->deg;
    514:   if (steps)   *steps   = ctx->steps;
    515:   if (npoints) *npoints = ctx->npoints;
    516:   PetscFunctionReturn(PETSC_SUCCESS);
    517: }

    519: /*@
    520:    EPSEVSLGetDOSParameters - Gets the parameters used for computing the
    521:    density of states (DOS) in the EVSL solver.

    523:    Not Collective

    525:    Input Parameter:
    526: .  eps - the eigensolver context

    528:    Output Parameters:
    529: +  dos     - DOS method, either KPM or Lanczos
    530: .  nvec    - number of sample vectors
    531: .  deg     - polynomial degree (KPM only)
    532: .  steps   - number of Lanczos steps (Lanczos only)
    533: -  npoints - number of sample points (Lanczos only)

    535:    Level: intermediate

    537: .seealso: EPSEVSLSetDOSParameters()
    538: @*/
    539: PetscErrorCode EPSEVSLGetDOSParameters(EPS eps,EPSEVSLDOSMethod *dos,PetscInt *nvec,PetscInt *deg,PetscInt *steps,PetscInt *npoints)
    540: {
    541:   PetscFunctionBegin;
    543:   PetscUseMethod(eps,"EPSEVSLGetDOSParameters_C",(EPS,EPSEVSLDOSMethod*,PetscInt*,PetscInt*,PetscInt*,PetscInt*),(eps,dos,nvec,deg,steps,npoints));
    544:   PetscFunctionReturn(PETSC_SUCCESS);
    545: }

    547: static PetscErrorCode EPSEVSLSetPolParameters_EVSL(EPS eps,PetscInt max_deg,PetscReal thresh)
    548: {
    549:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    551:   PetscFunctionBegin;
    552:   if (max_deg == PETSC_DETERMINE) ctx->max_deg = 10000;
    553:   else if (max_deg != PETSC_CURRENT) {
    554:     PetscCheck(max_deg>2,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"The max_deg argument must be > 2");
    555:     ctx->max_deg = max_deg;
    556:   }
    557:   if (thresh == (PetscReal)PETSC_DETERMINE) ctx->thresh = 0.8;
    558:   else if (thresh != (PetscReal)PETSC_CURRENT) {
    559:     PetscCheck(thresh>0.0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"The thresh argument must be > 0.0");
    560:     ctx->thresh = thresh;
    561:   }
    562:   eps->state = EPS_STATE_INITIAL;
    563:   PetscFunctionReturn(PETSC_SUCCESS);
    564: }

    566: /*@
    567:    EPSEVSLSetPolParameters - Defines the parameters used for building the
    568:    building the polynomial in the EVSL solver.

    570:    Logically Collective

    572:    Input Parameters:
    573: +  eps     - the eigensolver context
    574: .  max_deg - maximum degree allowed for the polynomial
    575: -  thresh  - threshold for accepting polynomial

    577:    Options Database Keys:
    578: +  -eps_evsl_pol_max_deg <d> - set maximum polynomial degree
    579: -  -eps_evsl_pol_thresh <t> - set the threshold

    581:    Note:
    582:    PETSC_CURRENT can be used to preserve the current value of any of the
    583:    arguments, and PETSC_DETERMINE to set them to a default value.

    585:    Level: intermediate

    587: .seealso: EPSEVSLGetPolParameters()
    588: @*/
    589: PetscErrorCode EPSEVSLSetPolParameters(EPS eps,PetscInt max_deg,PetscReal thresh)
    590: {
    591:   PetscFunctionBegin;
    595:   PetscTryMethod(eps,"EPSEVSLSetPolParameters_C",(EPS,PetscInt,PetscReal),(eps,max_deg,thresh));
    596:   PetscFunctionReturn(PETSC_SUCCESS);
    597: }

    599: static PetscErrorCode EPSEVSLGetPolParameters_EVSL(EPS eps,PetscInt *max_deg,PetscReal *thresh)
    600: {
    601:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    603:   PetscFunctionBegin;
    604:   if (max_deg) *max_deg = ctx->max_deg;
    605:   if (thresh)  *thresh  = ctx->thresh;
    606:   PetscFunctionReturn(PETSC_SUCCESS);
    607: }

    609: /*@
    610:    EPSEVSLGetPolParameters - Gets the parameters used for building the
    611:    polynomial in the EVSL solver.

    613:    Not Collective

    615:    Input Parameter:
    616: .  eps - the eigensolver context

    618:    Output Parameters:
    619: +  max_deg - the maximum degree of the polynomial
    620: -  thresh  - the threshold

    622:    Level: intermediate

    624: .seealso: EPSEVSLSetPolParameters()
    625: @*/
    626: PetscErrorCode EPSEVSLGetPolParameters(EPS eps,PetscInt *max_deg,PetscReal *thresh)
    627: {
    628:   PetscFunctionBegin;
    630:   PetscUseMethod(eps,"EPSEVSLGetPolParameters_C",(EPS,PetscInt*,PetscReal*),(eps,max_deg,thresh));
    631:   PetscFunctionReturn(PETSC_SUCCESS);
    632: }

    634: static PetscErrorCode EPSEVSLSetDamping_EVSL(EPS eps,EPSEVSLDamping damping)
    635: {
    636:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    638:   PetscFunctionBegin;
    639:   if (ctx->damping != damping) {
    640:     ctx->damping = damping;
    641:     eps->state   = EPS_STATE_INITIAL;
    642:   }
    643:   PetscFunctionReturn(PETSC_SUCCESS);
    644: }

    646: /*@
    647:    EPSEVSLSetDamping - Set the type of damping to be used in EVSL.

    649:    Logically Collective

    651:    Input Parameters:
    652: +  eps     - the eigensolver context
    653: -  damping - the type of damping

    655:    Options Database Key:
    656: .  -eps_evsl_damping <n> - set the type of damping

    658:    Notes:
    659:    Damping is applied when building the polynomial to be used when solving the
    660:    eigenproblem, and also during estimation of DOS with the KPM method.

    662:    Level: intermediate

    664: .seealso: EPSEVSLGetDamping(), EPSEVSLSetDOSParameters()
    665: @*/
    666: PetscErrorCode EPSEVSLSetDamping(EPS eps,EPSEVSLDamping damping)
    667: {
    668:   PetscFunctionBegin;
    671:   PetscTryMethod(eps,"EPSEVSLSetDamping_C",(EPS,EPSEVSLDamping),(eps,damping));
    672:   PetscFunctionReturn(PETSC_SUCCESS);
    673: }

    675: static PetscErrorCode EPSEVSLGetDamping_EVSL(EPS eps,EPSEVSLDamping *damping)
    676: {
    677:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    679:   PetscFunctionBegin;
    680:   *damping = ctx->damping;
    681:   PetscFunctionReturn(PETSC_SUCCESS);
    682: }

    684: /*@
    685:    EPSEVSLGetDamping - Gets the type of damping.

    687:    Not Collective

    689:    Input Parameter:
    690: .  eps - the eigensolver context

    692:    Output Parameter:
    693: .  damping - the type of damping

    695:    Level: intermediate

    697: .seealso: EPSEVSLSetDamping()
    698: @*/
    699: PetscErrorCode EPSEVSLGetDamping(EPS eps,EPSEVSLDamping *damping)
    700: {
    701:   PetscFunctionBegin;
    703:   PetscAssertPointer(damping,2);
    704:   PetscUseMethod(eps,"EPSEVSLGetDamping_C",(EPS,EPSEVSLDamping*),(eps,damping));
    705:   PetscFunctionReturn(PETSC_SUCCESS);
    706: }

    708: static PetscErrorCode EPSView_EVSL(EPS eps,PetscViewer viewer)
    709: {
    710:   PetscBool      isascii;
    711:   EPS_EVSL       *ctx = (EPS_EVSL*)eps->data;

    713:   PetscFunctionBegin;
    714:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isascii));
    715:   if (isascii) {
    716:     PetscCall(PetscViewerASCIIPrintf(viewer,"  numerical range = [%g,%g]\n",(double)ctx->lmin,(double)ctx->lmax));
    717:     PetscCall(PetscViewerASCIIPrintf(viewer,"  number of slices = %" PetscInt_FMT "\n",ctx->nslices));
    718:     PetscCall(PetscViewerASCIIPrintf(viewer,"  type of damping = %s\n",EPSEVSLDampings[ctx->damping]));
    719:     PetscCall(PetscViewerASCIIPrintf(viewer,"  computing DOS with %s: nvec=%" PetscInt_FMT ", ",EPSEVSLDOSMethods[ctx->dos],ctx->nvec));
    720:     PetscCall(PetscViewerASCIIUseTabs(viewer,PETSC_FALSE));
    721:     switch (ctx->dos) {
    722:       case EPS_EVSL_DOS_KPM:
    723:         PetscCall(PetscViewerASCIIPrintf(viewer,"degree=%" PetscInt_FMT "\n",ctx->deg));
    724:         break;
    725:       case EPS_EVSL_DOS_LANCZOS:
    726:         PetscCall(PetscViewerASCIIPrintf(viewer,"steps=%" PetscInt_FMT ", npoints=%" PetscInt_FMT "\n",ctx->steps,ctx->npoints));
    727:         break;
    728:     }
    729:     PetscCall(PetscViewerASCIIUseTabs(viewer,PETSC_TRUE));
    730:     PetscCall(PetscViewerASCIIPrintf(viewer,"  polynomial parameters: max degree = %" PetscInt_FMT ", threshold = %g\n",ctx->max_deg,(double)ctx->thresh));
    731:   }
    732:   PetscFunctionReturn(PETSC_SUCCESS);
    733: }

    735: static PetscErrorCode EPSSetFromOptions_EVSL(EPS eps,PetscOptionItems *PetscOptionsObject)
    736: {
    737:   PetscReal        array[2]={0,0},th;
    738:   PetscInt         k,i1,i2,i3,i4;
    739:   PetscBool        flg,flg1;
    740:   EPSEVSLDOSMethod dos;
    741:   EPSEVSLDamping   damping;
    742:   EPS_EVSL         *ctx = (EPS_EVSL*)eps->data;

    744:   PetscFunctionBegin;
    745:   PetscOptionsHeadBegin(PetscOptionsObject,"EPS EVSL Options");

    747:     k = 2;
    748:     PetscCall(PetscOptionsRealArray("-eps_evsl_range","Interval containing all eigenvalues (two real values separated with a comma without spaces)","EPSEVSLSetRange",array,&k,&flg));
    749:     if (flg) {
    750:       PetscCheck(k>1,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_SIZ,"Must pass two values in -eps_evsl_range (comma-separated without spaces)");
    751:       PetscCall(EPSEVSLSetRange(eps,array[0],array[1]));
    752:     }

    754:     PetscCall(PetscOptionsInt("-eps_evsl_slices","Number of slices","EPSEVSLSetSlices",ctx->nslices,&i1,&flg));
    755:     if (flg) PetscCall(EPSEVSLSetSlices(eps,i1));

    757:     PetscCall(PetscOptionsEnum("-eps_evsl_damping","Type of damping","EPSEVSLSetDamping",EPSEVSLDampings,(PetscEnum)ctx->damping,(PetscEnum*)&damping,&flg));
    758:     if (flg) PetscCall(EPSEVSLSetDamping(eps,damping));

    760:     PetscCall(EPSEVSLGetDOSParameters(eps,&dos,&i1,&i2,&i3,&i4));
    761:     PetscCall(PetscOptionsEnum("-eps_evsl_dos_method","Method to compute the DOS","EPSEVSLSetDOSParameters",EPSEVSLDOSMethods,(PetscEnum)ctx->dos,(PetscEnum*)&dos,&flg));
    762:     PetscCall(PetscOptionsInt("-eps_evsl_dos_nvec","Number of sample vectors for DOS","EPSEVSLSetDOSParameters",i1,&i1,&flg1));
    763:     if (flg1) flg = PETSC_TRUE;
    764:     PetscCall(PetscOptionsInt("-eps_evsl_dos_degree","Polynomial degree used for DOS","EPSEVSLSetDOSParameters",i2,&i2,&flg1));
    765:     if (flg1) flg = PETSC_TRUE;
    766:     PetscCall(PetscOptionsInt("-eps_evsl_dos_steps","Number of Lanczos steps in DOS","EPSEVSLSetDOSParameters",i3,&i3,&flg1));
    767:     if (flg1) flg = PETSC_TRUE;
    768:     PetscCall(PetscOptionsInt("-eps_evsl_dos_npoints","Number of sample points used for DOS","EPSEVSLSetDOSParameters",i4,&i4,&flg1));
    769:     if (flg || flg1) PetscCall(EPSEVSLSetDOSParameters(eps,dos,i1,i2,i3,i4));

    771:     PetscCall(EPSEVSLGetPolParameters(eps,&i1,&th));
    772:     PetscCall(PetscOptionsInt("-eps_evsl_pol_max_deg","Maximum degree allowed for the polynomial","EPSEVSLSetPolParameters",i1,&i1,&flg));
    773:     PetscCall(PetscOptionsReal("-eps_evsl_pol_threshold","Threshold for accepting polynomial","EPSEVSLSetPolParameters",th,&th,&flg1));
    774:     if (flg || flg1) PetscCall(EPSEVSLSetPolParameters(eps,i1,th));

    776:   PetscOptionsHeadEnd();
    777:   PetscFunctionReturn(PETSC_SUCCESS);
    778: }

    780: static PetscErrorCode EPSDestroy_EVSL(EPS eps)
    781: {
    782:   EPS_EVSL       *ctx = (EPS_EVSL*)eps->data;

    784:   PetscFunctionBegin;
    785:   if (ctx->initialized) EVSLFinish();
    786:   PetscCall(PetscLayoutDestroy(&ctx->map));
    787:   PetscCall(PetscFree(ctx->sli));
    788:   PetscCall(PetscFree(eps->data));
    789:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetRange_C",NULL));
    790:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetRange_C",NULL));
    791:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetSlices_C",NULL));
    792:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetSlices_C",NULL));
    793:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetDOSParameters_C",NULL));
    794:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetDOSParameters_C",NULL));
    795:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetPolParameters_C",NULL));
    796:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetPolParameters_C",NULL));
    797:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetDamping_C",NULL));
    798:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetDamping_C",NULL));
    799:   PetscFunctionReturn(PETSC_SUCCESS);
    800: }

    802: static PetscErrorCode EPSReset_EVSL(EPS eps)
    803: {
    804:   EPS_EVSL       *ctx = (EPS_EVSL*)eps->data;

    806:   PetscFunctionBegin;
    807:   PetscCall(MatDestroy(&ctx->A));
    808:   PetscCall(VecDestroy(&ctx->x));
    809:   PetscCall(VecDestroy(&ctx->y));
    810:   PetscFunctionReturn(PETSC_SUCCESS);
    811: }

    813: SLEPC_EXTERN PetscErrorCode EPSCreate_EVSL(EPS eps)
    814: {
    815:   EPS_EVSL       *ctx;

    817:   PetscFunctionBegin;
    818:   PetscCall(PetscNew(&ctx));
    819:   eps->data = (void*)ctx;

    821:   ctx->nslices = 0;
    822:   ctx->lmin    = PETSC_MIN_REAL;
    823:   ctx->lmax    = PETSC_MAX_REAL;
    824:   ctx->dos     = EPS_EVSL_DOS_KPM;
    825:   ctx->nvec    = 80;
    826:   ctx->deg     = 300;
    827:   ctx->steps   = 40;
    828:   ctx->npoints = 200;
    829:   ctx->max_deg = 10000;
    830:   ctx->thresh  = 0.8;
    831:   ctx->damping = EPS_EVSL_DAMPING_SIGMA;

    833:   eps->categ = EPS_CATEGORY_OTHER;

    835:   eps->ops->solve          = EPSSolve_EVSL;
    836:   eps->ops->setup          = EPSSetUp_EVSL;
    837:   eps->ops->setupsort      = EPSSetUpSort_Basic;
    838:   eps->ops->setfromoptions = EPSSetFromOptions_EVSL;
    839:   eps->ops->destroy        = EPSDestroy_EVSL;
    840:   eps->ops->reset          = EPSReset_EVSL;
    841:   eps->ops->view           = EPSView_EVSL;
    842:   eps->ops->backtransform  = EPSBackTransform_Default;
    843:   eps->ops->setdefaultst   = EPSSetDefaultST_NoFactor;

    845:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetRange_C",EPSEVSLSetRange_EVSL));
    846:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetRange_C",EPSEVSLGetRange_EVSL));
    847:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetSlices_C",EPSEVSLSetSlices_EVSL));
    848:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetSlices_C",EPSEVSLGetSlices_EVSL));
    849:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetDOSParameters_C",EPSEVSLSetDOSParameters_EVSL));
    850:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetDOSParameters_C",EPSEVSLGetDOSParameters_EVSL));
    851:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetPolParameters_C",EPSEVSLSetPolParameters_EVSL));
    852:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetPolParameters_C",EPSEVSLGetPolParameters_EVSL));
    853:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetDamping_C",EPSEVSLSetDamping_EVSL));
    854:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetDamping_C",EPSEVSLGetDamping_EVSL));
    855:   PetscFunctionReturn(PETSC_SUCCESS);
    856: }