Date: 2024-09-25T09:33:16+00:00

Actual source code: evsl.c
slepc-3.21.2 2024-09-25
Report Typos and Errors

      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:   PetscCall(PetscObjectTypeCompare((PetscObject)eps->st,STSHIFT,&isshift));
     75:   PetscCheck(isshift,PetscObjectComm((PetscObject)eps),PETSC_ERR_SUP,"This solver does not support spectral transformations");

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    273: /*@
    274:    EPSEVSLSetSlices - Set the number of slices in which the interval must be
    275:    subdivided.

    277:    Logically Collective

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

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

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

    291:    Level: intermediate

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

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

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

    313: /*@
    314:    EPSEVSLGetSlices - Gets the number of slices in which the interval must be
    315:    subdivided.

    317:    Not Collective

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

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

    325:    Level: intermediate

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

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

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

    352: /*@
    353:    EPSEVSLSetRange - Defines the numerical range (or field of values) of the problem,
    354:    that is, the interval containing all eigenvalues.

    356:    Logically Collective

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

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

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

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

    374:    Level: intermediate

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

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

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

    398: /*@
    399:    EPSEVSLGetRange - Gets the interval containing all eigenvalues.

    401:    Not Collective

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

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

    410:    Level: intermediate

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

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

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

    458: /*@
    459:    EPSEVSLSetDOSParameters - Defines the parameters used for computing the
    460:    density of states (DOS) in the EVSL solver.

    462:    Logically Collective

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

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

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

    485:    Level: intermediate

    487: .seealso: EPSEVSLGetDOSParameters()
    488: @*/
    489: PetscErrorCode EPSEVSLSetDOSParameters(EPS eps,EPSEVSLDOSMethod dos,PetscInt nvec,PetscInt deg,PetscInt steps,PetscInt npoints)
    490: {
    491:   PetscFunctionBegin;
    498:   PetscTryMethod(eps,"EPSEVSLSetDOSParameters_C",(EPS,EPSEVSLDOSMethod,PetscInt,PetscInt,PetscInt,PetscInt),(eps,dos,nvec,deg,steps,npoints));
    499:   PetscFunctionReturn(PETSC_SUCCESS);
    500: }

    502: static PetscErrorCode EPSEVSLGetDOSParameters_EVSL(EPS eps,EPSEVSLDOSMethod *dos,PetscInt *nvec,PetscInt *deg,PetscInt *steps,PetscInt *npoints)
    503: {
    504:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    506:   PetscFunctionBegin;
    507:   if (dos)     *dos     = ctx->dos;
    508:   if (nvec)    *nvec    = ctx->nvec;
    509:   if (deg)     *deg     = ctx->deg;
    510:   if (steps)   *steps   = ctx->steps;
    511:   if (npoints) *npoints = ctx->npoints;
    512:   PetscFunctionReturn(PETSC_SUCCESS);
    513: }

    515: /*@
    516:    EPSEVSLGetDOSParameters - Gets the parameters used for computing the
    517:    density of states (DOS) in the EVSL solver.

    519:    Not Collective

    521:    Input Parameter:
    522: .  eps - the eigensolver context

    524:    Output Parameters:
    525: +  dos     - DOS method, either KPM or Lanczos
    526: .  nvec    - number of sample vectors
    527: .  deg     - polynomial degree (KPM only)
    528: .  steps   - number of Lanczos steps (Lanczos only)
    529: -  npoints - number of sample points (Lanczos only)

    531:    Level: intermediate

    533: .seealso: EPSEVSLSetDOSParameters()
    534: @*/
    535: PetscErrorCode EPSEVSLGetDOSParameters(EPS eps,EPSEVSLDOSMethod *dos,PetscInt *nvec,PetscInt *deg,PetscInt *steps,PetscInt *npoints)
    536: {
    537:   PetscFunctionBegin;
    539:   PetscUseMethod(eps,"EPSEVSLGetDOSParameters_C",(EPS,EPSEVSLDOSMethod*,PetscInt*,PetscInt*,PetscInt*,PetscInt*),(eps,dos,nvec,deg,steps,npoints));
    540:   PetscFunctionReturn(PETSC_SUCCESS);
    541: }

    543: static PetscErrorCode EPSEVSLSetPolParameters_EVSL(EPS eps,PetscInt max_deg,PetscReal thresh)
    544: {
    545:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    547:   PetscFunctionBegin;
    548:   if (max_deg == PETSC_DECIDE || max_deg == PETSC_DEFAULT) ctx->max_deg = 10000;
    549:   else {
    550:     PetscCheck(max_deg>2,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"The max_deg argument must be > 2");
    551:     ctx->max_deg = max_deg;
    552:   }
    553:   if (thresh == (PetscReal)PETSC_DECIDE || thresh == (PetscReal)PETSC_DEFAULT) ctx->thresh = 0.8;
    554:   else {
    555:     PetscCheck(thresh>0.0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"The thresh argument must be > 0.0");
    556:     ctx->thresh = thresh;
    557:   }
    558:   eps->state = EPS_STATE_INITIAL;
    559:   PetscFunctionReturn(PETSC_SUCCESS);
    560: }

    562: /*@
    563:    EPSEVSLSetPolParameters - Defines the parameters used for building the
    564:    building the polynomial in the EVSL solver.

    566:    Logically Collective

    568:    Input Parameters:
    569: +  eps     - the eigensolver context
    570: .  max_deg - maximum degree allowed for the polynomial
    571: -  thresh  - threshold for accepting polynomial

    573:    Options Database Keys:
    574: +  -eps_evsl_pol_max_deg <d> - set maximum polynomial degree
    575: -  -eps_evsl_pol_thresh <t> - set the threshold

    577:    Level: intermediate

    579: .seealso: EPSEVSLGetPolParameters()
    580: @*/
    581: PetscErrorCode EPSEVSLSetPolParameters(EPS eps,PetscInt max_deg,PetscReal thresh)
    582: {
    583:   PetscFunctionBegin;
    587:   PetscTryMethod(eps,"EPSEVSLSetPolParameters_C",(EPS,PetscInt,PetscReal),(eps,max_deg,thresh));
    588:   PetscFunctionReturn(PETSC_SUCCESS);
    589: }

    591: static PetscErrorCode EPSEVSLGetPolParameters_EVSL(EPS eps,PetscInt *max_deg,PetscReal *thresh)
    592: {
    593:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    595:   PetscFunctionBegin;
    596:   if (max_deg) *max_deg = ctx->max_deg;
    597:   if (thresh)  *thresh  = ctx->thresh;
    598:   PetscFunctionReturn(PETSC_SUCCESS);
    599: }

    601: /*@
    602:    EPSEVSLGetPolParameters - Gets the parameters used for building the
    603:    polynomial in the EVSL solver.

    605:    Not Collective

    607:    Input Parameter:
    608: .  eps - the eigensolver context

    610:    Output Parameters:
    611: +  max_deg - the maximum degree of the polynomial
    612: -  thresh  - the threshold

    614:    Level: intermediate

    616: .seealso: EPSEVSLSetPolParameters()
    617: @*/
    618: PetscErrorCode EPSEVSLGetPolParameters(EPS eps,PetscInt *max_deg,PetscReal *thresh)
    619: {
    620:   PetscFunctionBegin;
    622:   PetscUseMethod(eps,"EPSEVSLGetPolParameters_C",(EPS,PetscInt*,PetscReal*),(eps,max_deg,thresh));
    623:   PetscFunctionReturn(PETSC_SUCCESS);
    624: }

    626: static PetscErrorCode EPSEVSLSetDamping_EVSL(EPS eps,EPSEVSLDamping damping)
    627: {
    628:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    630:   PetscFunctionBegin;
    631:   if (ctx->damping != damping) {
    632:     ctx->damping = damping;
    633:     eps->state   = EPS_STATE_INITIAL;
    634:   }
    635:   PetscFunctionReturn(PETSC_SUCCESS);
    636: }

    638: /*@
    639:    EPSEVSLSetDamping - Set the type of damping to be used in EVSL.

    641:    Logically Collective

    643:    Input Parameters:
    644: +  eps     - the eigensolver context
    645: -  damping - the type of damping

    647:    Options Database Key:
    648: .  -eps_evsl_damping <n> - set the type of damping

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

    654:    Level: intermediate

    656: .seealso: EPSEVSLGetDamping(), EPSEVSLSetDOSParameters()
    657: @*/
    658: PetscErrorCode EPSEVSLSetDamping(EPS eps,EPSEVSLDamping damping)
    659: {
    660:   PetscFunctionBegin;
    663:   PetscTryMethod(eps,"EPSEVSLSetDamping_C",(EPS,EPSEVSLDamping),(eps,damping));
    664:   PetscFunctionReturn(PETSC_SUCCESS);
    665: }

    667: static PetscErrorCode EPSEVSLGetDamping_EVSL(EPS eps,EPSEVSLDamping *damping)
    668: {
    669:   EPS_EVSL *ctx = (EPS_EVSL*)eps->data;

    671:   PetscFunctionBegin;
    672:   *damping = ctx->damping;
    673:   PetscFunctionReturn(PETSC_SUCCESS);
    674: }

    676: /*@
    677:    EPSEVSLGetDamping - Gets the type of damping.

    679:    Not Collective

    681:    Input Parameter:
    682: .  eps - the eigensolver context

    684:    Output Parameter:
    685: .  damping - the type of damping

    687:    Level: intermediate

    689: .seealso: EPSEVSLSetDamping()
    690: @*/
    691: PetscErrorCode EPSEVSLGetDamping(EPS eps,EPSEVSLDamping *damping)
    692: {
    693:   PetscFunctionBegin;
    695:   PetscAssertPointer(damping,2);
    696:   PetscUseMethod(eps,"EPSEVSLGetDamping_C",(EPS,EPSEVSLDamping*),(eps,damping));
    697:   PetscFunctionReturn(PETSC_SUCCESS);
    698: }

    700: static PetscErrorCode EPSView_EVSL(EPS eps,PetscViewer viewer)
    701: {
    702:   PetscBool      isascii;
    703:   EPS_EVSL       *ctx = (EPS_EVSL*)eps->data;

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

    727: static PetscErrorCode EPSSetFromOptions_EVSL(EPS eps,PetscOptionItems *PetscOptionsObject)
    728: {
    729:   PetscReal        array[2]={0,0},th;
    730:   PetscInt         k,i1,i2,i3,i4;
    731:   PetscBool        flg,flg1;
    732:   EPSEVSLDOSMethod dos;
    733:   EPSEVSLDamping   damping;
    734:   EPS_EVSL         *ctx = (EPS_EVSL*)eps->data;

    736:   PetscFunctionBegin;
    737:   PetscOptionsHeadBegin(PetscOptionsObject,"EPS EVSL Options");

    739:     k = 2;
    740:     PetscCall(PetscOptionsRealArray("-eps_evsl_range","Interval containing all eigenvalues (two real values separated with a comma without spaces)","EPSEVSLSetRange",array,&k,&flg));
    741:     if (flg) {
    742:       PetscCheck(k>1,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_SIZ,"Must pass two values in -eps_evsl_range (comma-separated without spaces)");
    743:       PetscCall(EPSEVSLSetRange(eps,array[0],array[1]));
    744:     }

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

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

    752:     PetscCall(EPSEVSLGetDOSParameters(eps,&dos,&i1,&i2,&i3,&i4));
    753:     PetscCall(PetscOptionsEnum("-eps_evsl_dos_method","Method to compute the DOS","EPSEVSLSetDOSParameters",EPSEVSLDOSMethods,(PetscEnum)ctx->dos,(PetscEnum*)&dos,&flg));
    754:     PetscCall(PetscOptionsInt("-eps_evsl_dos_nvec","Number of sample vectors for DOS","EPSEVSLSetDOSParameters",i1,&i1,&flg1));
    755:     if (flg1) flg = PETSC_TRUE;
    756:     PetscCall(PetscOptionsInt("-eps_evsl_dos_degree","Polynomial degree used for DOS","EPSEVSLSetDOSParameters",i2,&i2,&flg1));
    757:     if (flg1) flg = PETSC_TRUE;
    758:     PetscCall(PetscOptionsInt("-eps_evsl_dos_steps","Number of Lanczos steps in DOS","EPSEVSLSetDOSParameters",i3,&i3,&flg1));
    759:     if (flg1) flg = PETSC_TRUE;
    760:     PetscCall(PetscOptionsInt("-eps_evsl_dos_npoints","Number of sample points used for DOS","EPSEVSLSetDOSParameters",i4,&i4,&flg1));
    761:     if (flg || flg1) PetscCall(EPSEVSLSetDOSParameters(eps,dos,i1,i2,i3,i4));

    763:     PetscCall(EPSEVSLGetPolParameters(eps,&i1,&th));
    764:     PetscCall(PetscOptionsInt("-eps_evsl_pol_max_deg","Maximum degree allowed for the polynomial","EPSEVSLSetPolParameters",i1,&i1,&flg));
    765:     PetscCall(PetscOptionsReal("-eps_evsl_pol_threshold","Threshold for accepting polynomial","EPSEVSLSetPolParameters",th,&th,&flg1));
    766:     if (flg || flg1) PetscCall(EPSEVSLSetPolParameters(eps,i1,th));

    768:   PetscOptionsHeadEnd();
    769:   PetscFunctionReturn(PETSC_SUCCESS);
    770: }

    772: static PetscErrorCode EPSDestroy_EVSL(EPS eps)
    773: {
    774:   EPS_EVSL       *ctx = (EPS_EVSL*)eps->data;

    776:   PetscFunctionBegin;
    777:   if (ctx->initialized) EVSLFinish();
    778:   PetscCall(PetscLayoutDestroy(&ctx->map));
    779:   PetscCall(PetscFree(ctx->sli));
    780:   PetscCall(PetscFree(eps->data));
    781:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetRange_C",NULL));
    782:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetRange_C",NULL));
    783:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetSlices_C",NULL));
    784:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetSlices_C",NULL));
    785:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetDOSParameters_C",NULL));
    786:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetDOSParameters_C",NULL));
    787:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetPolParameters_C",NULL));
    788:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetPolParameters_C",NULL));
    789:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetDamping_C",NULL));
    790:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetDamping_C",NULL));
    791:   PetscFunctionReturn(PETSC_SUCCESS);
    792: }

    794: static PetscErrorCode EPSReset_EVSL(EPS eps)
    795: {
    796:   EPS_EVSL       *ctx = (EPS_EVSL*)eps->data;

    798:   PetscFunctionBegin;
    799:   PetscCall(MatDestroy(&ctx->A));
    800:   PetscCall(VecDestroy(&ctx->x));
    801:   PetscCall(VecDestroy(&ctx->y));
    802:   PetscFunctionReturn(PETSC_SUCCESS);
    803: }

    805: SLEPC_EXTERN PetscErrorCode EPSCreate_EVSL(EPS eps)
    806: {
    807:   EPS_EVSL       *ctx;

    809:   PetscFunctionBegin;
    810:   PetscCall(PetscNew(&ctx));
    811:   eps->data = (void*)ctx;

    813:   ctx->nslices = 0;
    814:   ctx->lmin    = PETSC_MIN_REAL;
    815:   ctx->lmax    = PETSC_MAX_REAL;
    816:   ctx->dos     = EPS_EVSL_DOS_KPM;
    817:   ctx->nvec    = 80;
    818:   ctx->deg     = 300;
    819:   ctx->steps   = 40;
    820:   ctx->npoints = 200;
    821:   ctx->max_deg = 10000;
    822:   ctx->thresh  = 0.8;
    823:   ctx->damping = EPS_EVSL_DAMPING_SIGMA;

    825:   eps->categ = EPS_CATEGORY_OTHER;

    827:   eps->ops->solve          = EPSSolve_EVSL;
    828:   eps->ops->setup          = EPSSetUp_EVSL;
    829:   eps->ops->setupsort      = EPSSetUpSort_Basic;
    830:   eps->ops->setfromoptions = EPSSetFromOptions_EVSL;
    831:   eps->ops->destroy        = EPSDestroy_EVSL;
    832:   eps->ops->reset          = EPSReset_EVSL;
    833:   eps->ops->view           = EPSView_EVSL;
    834:   eps->ops->backtransform  = EPSBackTransform_Default;
    835:   eps->ops->setdefaultst   = EPSSetDefaultST_NoFactor;

    837:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetRange_C",EPSEVSLSetRange_EVSL));
    838:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetRange_C",EPSEVSLGetRange_EVSL));
    839:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetSlices_C",EPSEVSLSetSlices_EVSL));
    840:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetSlices_C",EPSEVSLGetSlices_EVSL));
    841:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetDOSParameters_C",EPSEVSLSetDOSParameters_EVSL));
    842:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetDOSParameters_C",EPSEVSLGetDOSParameters_EVSL));
    843:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetPolParameters_C",EPSEVSLSetPolParameters_EVSL));
    844:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetPolParameters_C",EPSEVSLGetPolParameters_EVSL));
    845:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLSetDamping_C",EPSEVSLSetDamping_EVSL));
    846:   PetscCall(PetscObjectComposeFunction((PetscObject)eps,"EPSEVSLGetDamping_C",EPSEVSLGetDamping_EVSL));
    847:   PetscFunctionReturn(PETSC_SUCCESS);
    848: }