Date: 2024-09-25T09:34:09+00:00

Actual source code: cross.c
slepc-3.21.2 2024-09-25
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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:    SLEPc singular value solver: "cross"

     13:    Method: Uses a Hermitian eigensolver for A^T*A
     14: */

     16: #include <slepc/private/svdimpl.h>

     18: typedef struct {
     19:   PetscBool explicitmatrix;
     20:   EPS       eps;
     21:   PetscBool usereps;
     22:   Mat       C,D;
     23: } SVD_CROSS;

     25: typedef struct {
     26:   Mat       A,AT;
     27:   Vec       w,diag,omega;
     28:   PetscBool swapped;
     29: } SVD_CROSS_SHELL;

     31: static PetscErrorCode MatMult_Cross(Mat B,Vec x,Vec y)
     32: {
     33:   SVD_CROSS_SHELL *ctx;

     35:   PetscFunctionBegin;
     36:   PetscCall(MatShellGetContext(B,&ctx));
     37:   PetscCall(MatMult(ctx->A,x,ctx->w));
     38:   if (ctx->omega && !ctx->swapped) PetscCall(VecPointwiseMult(ctx->w,ctx->w,ctx->omega));
     39:   PetscCall(MatMult(ctx->AT,ctx->w,y));
     40:   PetscFunctionReturn(PETSC_SUCCESS);
     41: }

     43: static PetscErrorCode MatGetDiagonal_Cross(Mat B,Vec d)
     44: {
     45:   SVD_CROSS_SHELL   *ctx;
     46:   PetscMPIInt       len;
     47:   PetscInt          N,n,i,j,start,end,ncols;
     48:   PetscScalar       *work1,*work2,*diag;
     49:   const PetscInt    *cols;
     50:   const PetscScalar *vals;

     52:   PetscFunctionBegin;
     53:   PetscCall(MatShellGetContext(B,&ctx));
     54:   if (!ctx->diag) {
     55:     /* compute diagonal from rows and store in ctx->diag */
     56:     PetscCall(VecDuplicate(d,&ctx->diag));
     57:     PetscCall(MatGetSize(ctx->A,NULL,&N));
     58:     PetscCall(MatGetLocalSize(ctx->A,NULL,&n));
     59:     PetscCall(PetscCalloc2(N,&work1,N,&work2));
     60:     if (ctx->swapped) {
     61:       PetscCall(MatGetOwnershipRange(ctx->AT,&start,&end));
     62:       for (i=start;i<end;i++) {
     63:         PetscCall(MatGetRow(ctx->AT,i,&ncols,NULL,&vals));
     64:         for (j=0;j<ncols;j++) work1[i] += vals[j]*vals[j];
     65:         PetscCall(MatRestoreRow(ctx->AT,i,&ncols,NULL,&vals));
     66:       }
     67:     } else {
     68:       PetscCall(MatGetOwnershipRange(ctx->A,&start,&end));
     69:       for (i=start;i<end;i++) {
     70:         PetscCall(MatGetRow(ctx->A,i,&ncols,&cols,&vals));
     71:         for (j=0;j<ncols;j++) work1[cols[j]] += vals[j]*vals[j];
     72:         PetscCall(MatRestoreRow(ctx->A,i,&ncols,&cols,&vals));
     73:       }
     74:     }
     75:     PetscCall(PetscMPIIntCast(N,&len));
     76:     PetscCall(MPIU_Allreduce(work1,work2,len,MPIU_SCALAR,MPIU_SUM,PetscObjectComm((PetscObject)B)));
     77:     PetscCall(VecGetOwnershipRange(ctx->diag,&start,&end));
     78:     PetscCall(VecGetArrayWrite(ctx->diag,&diag));
     79:     for (i=start;i<end;i++) diag[i-start] = work2[i];
     80:     PetscCall(VecRestoreArrayWrite(ctx->diag,&diag));
     81:     PetscCall(PetscFree2(work1,work2));
     82:   }
     83:   PetscCall(VecCopy(ctx->diag,d));
     84:   PetscFunctionReturn(PETSC_SUCCESS);
     85: }

     87: static PetscErrorCode MatDestroy_Cross(Mat B)
     88: {
     89:   SVD_CROSS_SHELL *ctx;

     91:   PetscFunctionBegin;
     92:   PetscCall(MatShellGetContext(B,&ctx));
     93:   PetscCall(VecDestroy(&ctx->w));
     94:   PetscCall(VecDestroy(&ctx->diag));
     95:   PetscCall(PetscFree(ctx));
     96:   PetscFunctionReturn(PETSC_SUCCESS);
     97: }

     99: static PetscErrorCode SVDCrossGetProductMat(SVD svd,Mat A,Mat AT,Mat *C)
    100: {
    101:   SVD_CROSS       *cross = (SVD_CROSS*)svd->data;
    102:   SVD_CROSS_SHELL *ctx;
    103:   PetscInt        n;
    104:   VecType         vtype;
    105:   Mat             B;

    107:   PetscFunctionBegin;
    108:   if (cross->explicitmatrix) {
    109:     if (!svd->ishyperbolic || svd->swapped) B = (!svd->expltrans && svd->swapped)? AT: A;
    110:     else {  /* duplicate A and scale by signature */
    111:       PetscCall(MatDuplicate(A,MAT_COPY_VALUES,&B));
    112:       PetscCall(MatDiagonalScale(B,svd->omega,NULL));
    113:     }
    114:     if (svd->expltrans) {  /* explicit transpose */
    115:       PetscCall(MatProductCreate(AT,B,NULL,C));
    116:       PetscCall(MatProductSetType(*C,MATPRODUCT_AB));
    117:     } else {  /* implicit transpose */
    118: #if defined(PETSC_USE_COMPLEX)
    119:       SETERRQ(PetscObjectComm((PetscObject)svd),PETSC_ERR_SUP,"Must use explicit transpose with complex scalars");
    120: #else
    121:       if (!svd->swapped) {
    122:         PetscCall(MatProductCreate(A,B,NULL,C));
    123:         PetscCall(MatProductSetType(*C,MATPRODUCT_AtB));
    124:       } else {
    125:         PetscCall(MatProductCreate(B,AT,NULL,C));
    126:         PetscCall(MatProductSetType(*C,MATPRODUCT_ABt));
    127:       }
    128: #endif
    129:     }
    130:     PetscCall(MatProductSetFromOptions(*C));
    131:     PetscCall(MatProductSymbolic(*C));
    132:     PetscCall(MatProductNumeric(*C));
    133:     if (svd->ishyperbolic && !svd->swapped) PetscCall(MatDestroy(&B));
    134:   } else {
    135:     PetscCall(PetscNew(&ctx));
    136:     ctx->A       = A;
    137:     ctx->AT      = AT;
    138:     ctx->omega   = svd->omega;
    139:     ctx->swapped = svd->swapped;
    140:     PetscCall(MatCreateVecs(A,NULL,&ctx->w));
    141:     PetscCall(MatGetLocalSize(A,NULL,&n));
    142:     PetscCall(MatCreateShell(PetscObjectComm((PetscObject)svd),n,n,PETSC_DETERMINE,PETSC_DETERMINE,(void*)ctx,C));
    143:     PetscCall(MatShellSetOperation(*C,MATOP_MULT,(void(*)(void))MatMult_Cross));
    144:     if (!svd->ishyperbolic || svd->swapped) PetscCall(MatShellSetOperation(*C,MATOP_GET_DIAGONAL,(void(*)(void))MatGetDiagonal_Cross));
    145:     PetscCall(MatShellSetOperation(*C,MATOP_DESTROY,(void(*)(void))MatDestroy_Cross));
    146:     PetscCall(MatGetVecType(A,&vtype));
    147:     PetscCall(MatSetVecType(*C,vtype));
    148:   }
    149:   PetscFunctionReturn(PETSC_SUCCESS);
    150: }

    152: /* Convergence test relative to the norm of R (used in GSVD only) */
    153: static PetscErrorCode EPSConv_Cross(EPS eps,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
    154: {
    155:   SVD svd = (SVD)ctx;

    157:   PetscFunctionBegin;
    158:   *errest = res/PetscMax(svd->nrma,svd->nrmb);
    159:   PetscFunctionReturn(PETSC_SUCCESS);
    160: }

    162: static PetscErrorCode SVDSetUp_Cross(SVD svd)
    163: {
    164:   SVD_CROSS      *cross = (SVD_CROSS*)svd->data;
    165:   ST             st;
    166:   PetscBool      trackall,issinv,isks;
    167:   EPSProblemType ptype;
    168:   EPSWhich       which;
    169:   Mat            Omega;
    170:   MatType        Atype;
    171:   PetscInt       n,N;

    173:   PetscFunctionBegin;
    174:   if (!cross->eps) PetscCall(SVDCrossGetEPS(svd,&cross->eps));
    175:   PetscCall(MatDestroy(&cross->C));
    176:   PetscCall(MatDestroy(&cross->D));
    177:   PetscCall(SVDCrossGetProductMat(svd,svd->A,svd->AT,&cross->C));
    178:   if (svd->isgeneralized) {
    179:     PetscCall(SVDCrossGetProductMat(svd,svd->B,svd->BT,&cross->D));
    180:     PetscCall(EPSSetOperators(cross->eps,cross->C,cross->D));
    181:     PetscCall(EPSGetProblemType(cross->eps,&ptype));
    182:     if (!ptype) PetscCall(EPSSetProblemType(cross->eps,EPS_GHEP));
    183:   } else if (svd->ishyperbolic && svd->swapped) {
    184:     PetscCall(MatGetType(svd->OP,&Atype));
    185:     PetscCall(MatGetSize(svd->A,NULL,&N));
    186:     PetscCall(MatGetLocalSize(svd->A,NULL,&n));
    187:     PetscCall(MatCreate(PetscObjectComm((PetscObject)svd),&Omega));
    188:     PetscCall(MatSetSizes(Omega,n,n,N,N));
    189:     PetscCall(MatSetType(Omega,Atype));
    190:     PetscCall(MatDiagonalSet(Omega,svd->omega,INSERT_VALUES));
    191:     PetscCall(EPSSetOperators(cross->eps,cross->C,Omega));
    192:     PetscCall(EPSSetProblemType(cross->eps,EPS_GHIEP));
    193:     PetscCall(MatDestroy(&Omega));
    194:   } else {
    195:     PetscCall(EPSSetOperators(cross->eps,cross->C,NULL));
    196:     PetscCall(EPSSetProblemType(cross->eps,EPS_HEP));
    197:   }
    198:   if (!cross->usereps) {
    199:     PetscCall(EPSGetST(cross->eps,&st));
    200:     PetscCall(PetscObjectTypeCompare((PetscObject)st,STSINVERT,&issinv));
    201:     PetscCall(PetscObjectTypeCompare((PetscObject)cross->eps,EPSKRYLOVSCHUR,&isks));
    202:     if (svd->isgeneralized && svd->which==SVD_SMALLEST) {
    203:       if (cross->explicitmatrix && isks && !issinv) {  /* default to shift-and-invert */
    204:         PetscCall(STSetType(st,STSINVERT));
    205:         PetscCall(EPSSetTarget(cross->eps,0.0));
    206:         which = EPS_TARGET_REAL;
    207:       } else which = issinv?EPS_TARGET_REAL:EPS_SMALLEST_REAL;
    208:     } else {
    209:       if (issinv) which = EPS_TARGET_MAGNITUDE;
    210:       else if (svd->ishyperbolic) which = svd->which==SVD_LARGEST?EPS_LARGEST_MAGNITUDE:EPS_SMALLEST_MAGNITUDE;
    211:       else which = svd->which==SVD_LARGEST?EPS_LARGEST_REAL:EPS_SMALLEST_REAL;
    212:     }
    213:     PetscCall(EPSSetWhichEigenpairs(cross->eps,which));
    214:     PetscCall(EPSSetDimensions(cross->eps,svd->nsv,svd->ncv,svd->mpd));
    215:     PetscCall(EPSSetTolerances(cross->eps,svd->tol==(PetscReal)PETSC_DEFAULT?SLEPC_DEFAULT_TOL/10.0:svd->tol,svd->max_it));
    216:     switch (svd->conv) {
    217:     case SVD_CONV_ABS:
    218:       PetscCall(EPSSetConvergenceTest(cross->eps,EPS_CONV_ABS));break;
    219:     case SVD_CONV_REL:
    220:       PetscCall(EPSSetConvergenceTest(cross->eps,EPS_CONV_REL));break;
    221:     case SVD_CONV_NORM:
    222:       if (svd->isgeneralized) {
    223:         if (!svd->nrma) PetscCall(MatNorm(svd->OP,NORM_INFINITY,&svd->nrma));
    224:         if (!svd->nrmb) PetscCall(MatNorm(svd->OPb,NORM_INFINITY,&svd->nrmb));
    225:         PetscCall(EPSSetConvergenceTestFunction(cross->eps,EPSConv_Cross,svd,NULL));
    226:       } else {
    227:         PetscCall(EPSSetConvergenceTest(cross->eps,EPS_CONV_NORM));break;
    228:       }
    229:       break;
    230:     case SVD_CONV_MAXIT:
    231:       SETERRQ(PetscObjectComm((PetscObject)svd),PETSC_ERR_SUP,"Maxit convergence test not supported in this solver");
    232:     case SVD_CONV_USER:
    233:       SETERRQ(PetscObjectComm((PetscObject)svd),PETSC_ERR_SUP,"User-defined convergence test not supported in this solver");
    234:     }
    235:   }
    236:   SVDCheckUnsupported(svd,SVD_FEATURE_STOPPING);
    237:   /* Transfer the trackall option from svd to eps */
    238:   PetscCall(SVDGetTrackAll(svd,&trackall));
    239:   PetscCall(EPSSetTrackAll(cross->eps,trackall));
    240:   /* Transfer the initial space from svd to eps */
    241:   if (svd->nini<0) {
    242:     PetscCall(EPSSetInitialSpace(cross->eps,-svd->nini,svd->IS));
    243:     PetscCall(SlepcBasisDestroy_Private(&svd->nini,&svd->IS));
    244:   }
    245:   PetscCall(EPSSetUp(cross->eps));
    246:   PetscCall(EPSGetDimensions(cross->eps,NULL,&svd->ncv,&svd->mpd));
    247:   PetscCall(EPSGetTolerances(cross->eps,NULL,&svd->max_it));
    248:   if (svd->tol==(PetscReal)PETSC_DEFAULT) svd->tol = SLEPC_DEFAULT_TOL;

    250:   svd->leftbasis = PETSC_FALSE;
    251:   PetscCall(SVDAllocateSolution(svd,0));
    252:   PetscFunctionReturn(PETSC_SUCCESS);
    253: }

    255: static PetscErrorCode SVDSolve_Cross(SVD svd)
    256: {
    257:   SVD_CROSS      *cross = (SVD_CROSS*)svd->data;
    258:   PetscInt       i;
    259:   PetscScalar    lambda;
    260:   PetscReal      sigma;

    262:   PetscFunctionBegin;
    263:   PetscCall(EPSSolve(cross->eps));
    264:   PetscCall(EPSGetConverged(cross->eps,&svd->nconv));
    265:   PetscCall(EPSGetIterationNumber(cross->eps,&svd->its));
    266:   PetscCall(EPSGetConvergedReason(cross->eps,(EPSConvergedReason*)&svd->reason));
    267:   for (i=0;i<svd->nconv;i++) {
    268:     PetscCall(EPSGetEigenvalue(cross->eps,i,&lambda,NULL));
    269:     sigma = PetscRealPart(lambda);
    270:     if (svd->ishyperbolic) svd->sigma[i] = PetscSqrtReal(PetscAbsReal(sigma));
    271:     else {
    272:       PetscCheck(sigma>-10*PETSC_MACHINE_EPSILON,PetscObjectComm((PetscObject)svd),PETSC_ERR_FP,"Negative eigenvalue computed by EPS: %g",(double)sigma);
    273:       if (sigma<0.0) {
    274:         PetscCall(PetscInfo(svd,"Negative eigenvalue computed by EPS: %g, resetting to 0\n",(double)sigma));
    275:         sigma = 0.0;
    276:       }
    277:       svd->sigma[i] = PetscSqrtReal(sigma);
    278:     }
    279:   }
    280:   PetscFunctionReturn(PETSC_SUCCESS);
    281: }

    283: static PetscErrorCode SVDComputeVectors_Cross(SVD svd)
    284: {
    285:   SVD_CROSS         *cross = (SVD_CROSS*)svd->data;
    286:   PetscInt          i,mloc,ploc;
    287:   Vec               u,v,x,uv,w,omega2=NULL;
    288:   Mat               Omega;
    289:   PetscScalar       *dst,alpha,lambda,*varray;
    290:   const PetscScalar *src;
    291:   PetscReal         nrm;

    293:   PetscFunctionBegin;
    294:   if (svd->isgeneralized) {
    295:     PetscCall(MatCreateVecs(svd->A,NULL,&u));
    296:     PetscCall(VecGetLocalSize(u,&mloc));
    297:     PetscCall(MatCreateVecs(svd->B,NULL,&v));
    298:     PetscCall(VecGetLocalSize(v,&ploc));
    299:     for (i=0;i<svd->nconv;i++) {
    300:       PetscCall(BVGetColumn(svd->V,i,&x));
    301:       PetscCall(EPSGetEigenpair(cross->eps,i,&lambda,NULL,x,NULL));
    302:       PetscCall(MatMult(svd->A,x,u));     /* u_i*c_i/alpha = A*x_i */
    303:       PetscCall(VecNormalize(u,NULL));
    304:       PetscCall(MatMult(svd->B,x,v));     /* v_i*s_i/alpha = B*x_i */
    305:       PetscCall(VecNormalize(v,&nrm));    /* ||v||_2 = s_i/alpha   */
    306:       alpha = 1.0/(PetscSqrtReal(1.0+PetscRealPart(lambda))*nrm);    /* alpha=s_i/||v||_2 */
    307:       PetscCall(VecScale(x,alpha));
    308:       PetscCall(BVRestoreColumn(svd->V,i,&x));
    309:       /* copy [u;v] to U[i] */
    310:       PetscCall(BVGetColumn(svd->U,i,&uv));
    311:       PetscCall(VecGetArrayWrite(uv,&dst));
    312:       PetscCall(VecGetArrayRead(u,&src));
    313:       PetscCall(PetscArraycpy(dst,src,mloc));
    314:       PetscCall(VecRestoreArrayRead(u,&src));
    315:       PetscCall(VecGetArrayRead(v,&src));
    316:       PetscCall(PetscArraycpy(dst+mloc,src,ploc));
    317:       PetscCall(VecRestoreArrayRead(v,&src));
    318:       PetscCall(VecRestoreArrayWrite(uv,&dst));
    319:       PetscCall(BVRestoreColumn(svd->U,i,&uv));
    320:     }
    321:     PetscCall(VecDestroy(&v));
    322:     PetscCall(VecDestroy(&u));
    323:   } else if (svd->ishyperbolic && svd->swapped) {  /* was solved as GHIEP, set u=Omega*u and normalize */
    324:     PetscCall(EPSGetOperators(cross->eps,NULL,&Omega));
    325:     PetscCall(MatCreateVecs(Omega,&w,NULL));
    326:     PetscCall(VecCreateSeq(PETSC_COMM_SELF,svd->ncv,&omega2));
    327:     PetscCall(VecGetArrayWrite(omega2,&varray));
    328:     for (i=0;i<svd->nconv;i++) {
    329:       PetscCall(BVGetColumn(svd->V,i,&v));
    330:       PetscCall(EPSGetEigenvector(cross->eps,i,v,NULL));
    331:       PetscCall(MatMult(Omega,v,w));
    332:       PetscCall(VecDot(v,w,&alpha));
    333:       svd->sign[i] = PetscSign(PetscRealPart(alpha));
    334:       varray[i] = svd->sign[i];
    335:       alpha = 1.0/PetscSqrtScalar(PetscAbsScalar(alpha));
    336:       PetscCall(VecScale(w,alpha));
    337:       PetscCall(VecCopy(w,v));
    338:       PetscCall(BVRestoreColumn(svd->V,i,&v));
    339:     }
    340:     PetscCall(BVSetSignature(svd->V,omega2));
    341:     PetscCall(VecRestoreArrayWrite(omega2,&varray));
    342:     PetscCall(VecDestroy(&omega2));
    343:     PetscCall(VecDestroy(&w));
    344:     PetscCall(SVDComputeVectors_Left(svd));
    345:   } else {
    346:     for (i=0;i<svd->nconv;i++) {
    347:       PetscCall(BVGetColumn(svd->V,i,&v));
    348:       PetscCall(EPSGetEigenvector(cross->eps,i,v,NULL));
    349:       PetscCall(BVRestoreColumn(svd->V,i,&v));
    350:     }
    351:     PetscCall(SVDComputeVectors_Left(svd));
    352:   }
    353:   PetscFunctionReturn(PETSC_SUCCESS);
    354: }

    356: static PetscErrorCode EPSMonitor_Cross(EPS eps,PetscInt its,PetscInt nconv,PetscScalar *eigr,PetscScalar *eigi,PetscReal *errest,PetscInt nest,void *ctx)
    357: {
    358:   PetscInt       i;
    359:   SVD            svd = (SVD)ctx;
    360:   PetscScalar    er,ei;
    361:   ST             st;

    363:   PetscFunctionBegin;
    364:   PetscCall(EPSGetST(eps,&st));
    365:   for (i=0;i<PetscMin(nest,svd->ncv);i++) {
    366:     er = eigr[i]; ei = eigi[i];
    367:     PetscCall(STBackTransform(st,1,&er,&ei));
    368:     svd->sigma[i] = PetscSqrtReal(PetscAbsReal(PetscRealPart(er)));
    369:     svd->errest[i] = errest[i];
    370:   }
    371:   PetscCall(SVDMonitor(svd,its,nconv,svd->sigma,svd->errest,nest));
    372:   PetscFunctionReturn(PETSC_SUCCESS);
    373: }

    375: static PetscErrorCode SVDSetFromOptions_Cross(SVD svd,PetscOptionItems *PetscOptionsObject)
    376: {
    377:   PetscBool      set,val;
    378:   SVD_CROSS      *cross = (SVD_CROSS*)svd->data;
    379:   ST             st;

    381:   PetscFunctionBegin;
    382:   PetscOptionsHeadBegin(PetscOptionsObject,"SVD Cross Options");

    384:     PetscCall(PetscOptionsBool("-svd_cross_explicitmatrix","Use cross explicit matrix","SVDCrossSetExplicitMatrix",cross->explicitmatrix,&val,&set));
    385:     if (set) PetscCall(SVDCrossSetExplicitMatrix(svd,val));

    387:   PetscOptionsHeadEnd();

    389:   if (!cross->eps) PetscCall(SVDCrossGetEPS(svd,&cross->eps));
    390:   if (!cross->explicitmatrix && !cross->usereps) {
    391:     /* use as default an ST with shell matrix and Jacobi */
    392:     PetscCall(EPSGetST(cross->eps,&st));
    393:     PetscCall(STSetMatMode(st,ST_MATMODE_SHELL));
    394:   }
    395:   PetscCall(EPSSetFromOptions(cross->eps));
    396:   PetscFunctionReturn(PETSC_SUCCESS);
    397: }

    399: static PetscErrorCode SVDCrossSetExplicitMatrix_Cross(SVD svd,PetscBool explicitmatrix)
    400: {
    401:   SVD_CROSS *cross = (SVD_CROSS*)svd->data;

    403:   PetscFunctionBegin;
    404:   if (cross->explicitmatrix != explicitmatrix) {
    405:     cross->explicitmatrix = explicitmatrix;
    406:     svd->state = SVD_STATE_INITIAL;
    407:   }
    408:   PetscFunctionReturn(PETSC_SUCCESS);
    409: }

    411: /*@
    412:    SVDCrossSetExplicitMatrix - Indicate if the eigensolver operator A^T*A must
    413:    be computed explicitly.

    415:    Logically Collective

    417:    Input Parameters:
    418: +  svd         - singular value solver
    419: -  explicitmat - boolean flag indicating if A^T*A is built explicitly

    421:    Options Database Key:
    422: .  -svd_cross_explicitmatrix <boolean> - Indicates the boolean flag

    424:    Level: advanced

    426: .seealso: SVDCrossGetExplicitMatrix()
    427: @*/
    428: PetscErrorCode SVDCrossSetExplicitMatrix(SVD svd,PetscBool explicitmat)
    429: {
    430:   PetscFunctionBegin;
    433:   PetscTryMethod(svd,"SVDCrossSetExplicitMatrix_C",(SVD,PetscBool),(svd,explicitmat));
    434:   PetscFunctionReturn(PETSC_SUCCESS);
    435: }

    437: static PetscErrorCode SVDCrossGetExplicitMatrix_Cross(SVD svd,PetscBool *explicitmat)
    438: {
    439:   SVD_CROSS *cross = (SVD_CROSS*)svd->data;

    441:   PetscFunctionBegin;
    442:   *explicitmat = cross->explicitmatrix;
    443:   PetscFunctionReturn(PETSC_SUCCESS);
    444: }

    446: /*@
    447:    SVDCrossGetExplicitMatrix - Returns the flag indicating if A^T*A is built explicitly.

    449:    Not Collective

    451:    Input Parameter:
    452: .  svd  - singular value solver

    454:    Output Parameter:
    455: .  explicitmat - the mode flag

    457:    Level: advanced

    459: .seealso: SVDCrossSetExplicitMatrix()
    460: @*/
    461: PetscErrorCode SVDCrossGetExplicitMatrix(SVD svd,PetscBool *explicitmat)
    462: {
    463:   PetscFunctionBegin;
    465:   PetscAssertPointer(explicitmat,2);
    466:   PetscUseMethod(svd,"SVDCrossGetExplicitMatrix_C",(SVD,PetscBool*),(svd,explicitmat));
    467:   PetscFunctionReturn(PETSC_SUCCESS);
    468: }

    470: static PetscErrorCode SVDCrossSetEPS_Cross(SVD svd,EPS eps)
    471: {
    472:   SVD_CROSS      *cross = (SVD_CROSS*)svd->data;

    474:   PetscFunctionBegin;
    475:   PetscCall(PetscObjectReference((PetscObject)eps));
    476:   PetscCall(EPSDestroy(&cross->eps));
    477:   cross->eps     = eps;
    478:   cross->usereps = PETSC_TRUE;
    479:   svd->state     = SVD_STATE_INITIAL;
    480:   PetscFunctionReturn(PETSC_SUCCESS);
    481: }

    483: /*@
    484:    SVDCrossSetEPS - Associate an eigensolver object (EPS) to the
    485:    singular value solver.

    487:    Collective

    489:    Input Parameters:
    490: +  svd - singular value solver
    491: -  eps - the eigensolver object

    493:    Level: advanced

    495: .seealso: SVDCrossGetEPS()
    496: @*/
    497: PetscErrorCode SVDCrossSetEPS(SVD svd,EPS eps)
    498: {
    499:   PetscFunctionBegin;
    502:   PetscCheckSameComm(svd,1,eps,2);
    503:   PetscTryMethod(svd,"SVDCrossSetEPS_C",(SVD,EPS),(svd,eps));
    504:   PetscFunctionReturn(PETSC_SUCCESS);
    505: }

    507: static PetscErrorCode SVDCrossGetEPS_Cross(SVD svd,EPS *eps)
    508: {
    509:   SVD_CROSS      *cross = (SVD_CROSS*)svd->data;

    511:   PetscFunctionBegin;
    512:   if (!cross->eps) {
    513:     PetscCall(EPSCreate(PetscObjectComm((PetscObject)svd),&cross->eps));
    514:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)cross->eps,(PetscObject)svd,1));
    515:     PetscCall(EPSSetOptionsPrefix(cross->eps,((PetscObject)svd)->prefix));
    516:     PetscCall(EPSAppendOptionsPrefix(cross->eps,"svd_cross_"));
    517:     PetscCall(PetscObjectSetOptions((PetscObject)cross->eps,((PetscObject)svd)->options));
    518:     PetscCall(EPSSetWhichEigenpairs(cross->eps,EPS_LARGEST_REAL));
    519:     PetscCall(EPSMonitorSet(cross->eps,EPSMonitor_Cross,svd,NULL));
    520:   }
    521:   *eps = cross->eps;
    522:   PetscFunctionReturn(PETSC_SUCCESS);
    523: }

    525: /*@
    526:    SVDCrossGetEPS - Retrieve the eigensolver object (EPS) associated
    527:    to the singular value solver.

    529:    Collective

    531:    Input Parameter:
    532: .  svd - singular value solver

    534:    Output Parameter:
    535: .  eps - the eigensolver object

    537:    Level: advanced

    539: .seealso: SVDCrossSetEPS()
    540: @*/
    541: PetscErrorCode SVDCrossGetEPS(SVD svd,EPS *eps)
    542: {
    543:   PetscFunctionBegin;
    545:   PetscAssertPointer(eps,2);
    546:   PetscUseMethod(svd,"SVDCrossGetEPS_C",(SVD,EPS*),(svd,eps));
    547:   PetscFunctionReturn(PETSC_SUCCESS);
    548: }

    550: static PetscErrorCode SVDView_Cross(SVD svd,PetscViewer viewer)
    551: {
    552:   SVD_CROSS      *cross = (SVD_CROSS*)svd->data;
    553:   PetscBool      isascii;

    555:   PetscFunctionBegin;
    556:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isascii));
    557:   if (isascii) {
    558:     if (!cross->eps) PetscCall(SVDCrossGetEPS(svd,&cross->eps));
    559:     PetscCall(PetscViewerASCIIPrintf(viewer,"  %s matrix\n",cross->explicitmatrix?"explicit":"implicit"));
    560:     PetscCall(PetscViewerASCIIPushTab(viewer));
    561:     PetscCall(EPSView(cross->eps,viewer));
    562:     PetscCall(PetscViewerASCIIPopTab(viewer));
    563:   }
    564:   PetscFunctionReturn(PETSC_SUCCESS);
    565: }

    567: static PetscErrorCode SVDReset_Cross(SVD svd)
    568: {
    569:   SVD_CROSS      *cross = (SVD_CROSS*)svd->data;

    571:   PetscFunctionBegin;
    572:   PetscCall(EPSReset(cross->eps));
    573:   PetscCall(MatDestroy(&cross->C));
    574:   PetscCall(MatDestroy(&cross->D));
    575:   PetscFunctionReturn(PETSC_SUCCESS);
    576: }

    578: static PetscErrorCode SVDDestroy_Cross(SVD svd)
    579: {
    580:   SVD_CROSS      *cross = (SVD_CROSS*)svd->data;

    582:   PetscFunctionBegin;
    583:   PetscCall(EPSDestroy(&cross->eps));
    584:   PetscCall(PetscFree(svd->data));
    585:   PetscCall(PetscObjectComposeFunction((PetscObject)svd,"SVDCrossSetEPS_C",NULL));
    586:   PetscCall(PetscObjectComposeFunction((PetscObject)svd,"SVDCrossGetEPS_C",NULL));
    587:   PetscCall(PetscObjectComposeFunction((PetscObject)svd,"SVDCrossSetExplicitMatrix_C",NULL));
    588:   PetscCall(PetscObjectComposeFunction((PetscObject)svd,"SVDCrossGetExplicitMatrix_C",NULL));
    589:   PetscFunctionReturn(PETSC_SUCCESS);
    590: }

    592: SLEPC_EXTERN PetscErrorCode SVDCreate_Cross(SVD svd)
    593: {
    594:   SVD_CROSS      *cross;

    596:   PetscFunctionBegin;
    597:   PetscCall(PetscNew(&cross));
    598:   svd->data = (void*)cross;

    600:   svd->ops->solve          = SVDSolve_Cross;
    601:   svd->ops->solveg         = SVDSolve_Cross;
    602:   svd->ops->solveh         = SVDSolve_Cross;
    603:   svd->ops->setup          = SVDSetUp_Cross;
    604:   svd->ops->setfromoptions = SVDSetFromOptions_Cross;
    605:   svd->ops->destroy        = SVDDestroy_Cross;
    606:   svd->ops->reset          = SVDReset_Cross;
    607:   svd->ops->view           = SVDView_Cross;
    608:   svd->ops->computevectors = SVDComputeVectors_Cross;
    609:   PetscCall(PetscObjectComposeFunction((PetscObject)svd,"SVDCrossSetEPS_C",SVDCrossSetEPS_Cross));
    610:   PetscCall(PetscObjectComposeFunction((PetscObject)svd,"SVDCrossGetEPS_C",SVDCrossGetEPS_Cross));
    611:   PetscCall(PetscObjectComposeFunction((PetscObject)svd,"SVDCrossSetExplicitMatrix_C",SVDCrossSetExplicitMatrix_Cross));
    612:   PetscCall(PetscObjectComposeFunction((PetscObject)svd,"SVDCrossGetExplicitMatrix_C",SVDCrossGetExplicitMatrix_Cross));
    613:   PetscFunctionReturn(PETSC_SUCCESS);
    614: }