Date: 2026-03-31T13:23:29+00:00

Actual source code: test17.c

      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: */

     11: static char help[] = "Test interface functions of spectrum-slicing Krylov-Schur.\n\n"
     12:   "This is based on ex12.c. The command line options are:\n"
     13:   "  -n <n>, where <n> = number of grid subdivisions in x dimension.\n"
     14:   "  -m <m>, where <m> = number of grid subdivisions in y dimension.\n\n";

     16: #include <slepceps.h>

     18: int main(int argc,char **argv)
     19: {
     20:   Mat            A,B;         /* matrices */
     21:   Mat            As,Bs;       /* matrices distributed in subcommunicators */
     22:   Mat            Au;          /* matrix used to modify A on subcommunicators */
     23:   EPS            eps;         /* eigenproblem solver context */
     24:   ST             st;          /* spectral transformation context */
     25:   KSP            ksp;
     26:   PC             pc;
     27:   Vec            v;
     28:   PetscMPIInt    size,rank;
     29:   PetscInt       N,n=35,m,Istart,Iend,II,nev,ncv,mpd,i,j,k,*inertias,npart,nval,nloc,nlocs,mlocs;
     30:   PetscBool      flag,showinertia=PETSC_TRUE,lock,detect;
     31:   PetscReal      int0,int1,*shifts,keep,*subint,*evals;
     32:   PetscScalar    lambda;
     33:   char           vlist[4000];

     35:   PetscFunctionBeginUser;
     36:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
     37:   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD,&size));
     38:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD,&rank));

     40:   PetscCall(PetscOptionsGetBool(NULL,NULL,"-showinertia",&showinertia,NULL));
     41:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
     42:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag));
     43:   if (!flag) m=n;
     44:   N = n*m;
     45:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nSpectrum-slicing test, N=%" PetscInt_FMT " (%" PetscInt_FMT "x%" PetscInt_FMT " grid)\n\n",N,n,m));

     47:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     48:      Compute the matrices that define the eigensystem, Ax=kBx
     49:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     51:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
     52:   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,N,N));
     53:   PetscCall(MatSetFromOptions(A));

     55:   PetscCall(MatCreate(PETSC_COMM_WORLD,&B));
     56:   PetscCall(MatSetSizes(B,PETSC_DECIDE,PETSC_DECIDE,N,N));
     57:   PetscCall(MatSetFromOptions(B));

     59:   PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
     60:   for (II=Istart;II<Iend;II++) {
     61:     i = II/n; j = II-i*n;
     62:     if (i>0) PetscCall(MatSetValue(A,II,II-n,-1.0,INSERT_VALUES));
     63:     if (i<m-1) PetscCall(MatSetValue(A,II,II+n,-1.0,INSERT_VALUES));
     64:     if (j>0) PetscCall(MatSetValue(A,II,II-1,-1.0,INSERT_VALUES));
     65:     if (j<n-1) PetscCall(MatSetValue(A,II,II+1,-1.0,INSERT_VALUES));
     66:     PetscCall(MatSetValue(A,II,II,4.0,INSERT_VALUES));
     67:     PetscCall(MatSetValue(B,II,II,2.0,INSERT_VALUES));
     68:   }
     69:   if (Istart==0) {
     70:     PetscCall(MatSetValue(B,0,0,6.0,INSERT_VALUES));
     71:     PetscCall(MatSetValue(B,0,1,-1.0,INSERT_VALUES));
     72:     PetscCall(MatSetValue(B,1,0,-1.0,INSERT_VALUES));
     73:     PetscCall(MatSetValue(B,1,1,1.0,INSERT_VALUES));
     74:   }

     76:   PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
     77:   PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));
     78:   PetscCall(MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY));
     79:   PetscCall(MatAssemblyEnd(B,MAT_FINAL_ASSEMBLY));

     81:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     82:                 Create the eigensolver and set various options
     83:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     85:   PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
     86:   PetscCall(EPSSetOperators(eps,A,B));
     87:   PetscCall(EPSSetProblemType(eps,EPS_GHEP));
     88:   PetscCall(EPSSetType(eps,EPSKRYLOVSCHUR));

     90:   /*
     91:      Set interval and other settings for spectrum slicing
     92:   */
     93:   PetscCall(EPSSetWhichEigenpairs(eps,EPS_ALL));
     94:   int0 = 1.1; int1 = 1.3;
     95:   PetscCall(EPSSetInterval(eps,int0,int1));
     96:   PetscCall(EPSGetST(eps,&st));
     97:   PetscCall(STSetType(st,STSINVERT));
     98:   if (size>1) PetscCall(EPSKrylovSchurSetPartitions(eps,size));
     99:   PetscCall(EPSKrylovSchurGetKSP(eps,&ksp));
    100:   PetscCall(KSPGetPC(ksp,&pc));
    101:   PetscCall(KSPSetType(ksp,KSPPREONLY));
    102:   PetscCall(PCSetType(pc,PCCHOLESKY));

    104:   /*
    105:      Test interface functions of Krylov-Schur solver
    106:   */
    107:   PetscCall(EPSKrylovSchurGetRestart(eps,&keep));
    108:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Restart parameter before changing = %g",(double)keep));
    109:   PetscCall(EPSKrylovSchurSetRestart(eps,0.4));
    110:   PetscCall(EPSKrylovSchurGetRestart(eps,&keep));
    111:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," ... changed to %g\n",(double)keep));

    113:   PetscCall(EPSKrylovSchurGetDetectZeros(eps,&detect));
    114:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Detect zeros before changing = %d",(int)detect));
    115:   PetscCall(EPSKrylovSchurSetDetectZeros(eps,PETSC_TRUE));
    116:   PetscCall(EPSKrylovSchurGetDetectZeros(eps,&detect));
    117:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," ... changed to %d\n",(int)detect));

    119:   PetscCall(EPSKrylovSchurGetLocking(eps,&lock));
    120:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Locking flag before changing = %d",(int)lock));
    121:   PetscCall(EPSKrylovSchurSetLocking(eps,PETSC_FALSE));
    122:   PetscCall(EPSKrylovSchurGetLocking(eps,&lock));
    123:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," ... changed to %d\n",(int)lock));

    125:   PetscCall(EPSKrylovSchurGetDimensions(eps,&nev,&ncv,&mpd));
    126:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Sub-solve dimensions before changing = [%" PetscInt_FMT ",%" PetscInt_FMT ",%" PetscInt_FMT "]",nev,ncv,mpd));
    127:   PetscCall(EPSKrylovSchurSetDimensions(eps,30,60,60));
    128:   PetscCall(EPSKrylovSchurGetDimensions(eps,&nev,&ncv,&mpd));
    129:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," ... changed to [%" PetscInt_FMT ",%" PetscInt_FMT ",%" PetscInt_FMT "]\n",nev,ncv,mpd));

    131:   if (size>1) {
    132:     PetscCall(EPSKrylovSchurGetPartitions(eps,&npart));
    133:     PetscCall(PetscPrintf(PETSC_COMM_WORLD," Using %" PetscInt_FMT " partitions\n",npart));

    135:     PetscCall(PetscMalloc1(npart+1,&subint));
    136:     subint[0] = int0;
    137:     subint[npart] = int1;
    138:     for (i=1;i<npart;i++) subint[i] = int0+i*(int1-int0)/npart;
    139:     PetscCall(EPSKrylovSchurSetSubintervals(eps,subint));
    140:     PetscCall(PetscFree(subint));
    141:     PetscCall(EPSKrylovSchurGetSubintervals(eps,&subint));
    142:     PetscCall(PetscPrintf(PETSC_COMM_WORLD," Using sub-interval separations = "));
    143:     for (i=1;i<npart;i++) PetscCall(PetscPrintf(PETSC_COMM_WORLD," %g",(double)subint[i]));
    144:     PetscCall(PetscFree(subint));
    145:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\n"));
    146:   }

    148:   PetscCall(EPSSetFromOptions(eps));

    150:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    151:            Compute all eigenvalues in interval and display info
    152:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    154:   PetscCall(EPSSetUp(eps));
    155:   PetscCall(EPSKrylovSchurGetInertias(eps,&k,&shifts,&inertias));
    156:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Inertias after EPSSetUp:\n"));
    157:   for (i=0;i<k;i++) PetscCall(PetscPrintf(PETSC_COMM_WORLD," .. %g (%" PetscInt_FMT ")\n",(double)shifts[i],inertias[i]));
    158:   PetscCall(PetscFree(shifts));
    159:   PetscCall(PetscFree(inertias));

    161:   PetscCall(EPSSolve(eps));
    162:   PetscCall(EPSGetDimensions(eps,&nev,NULL,NULL));
    163:   PetscCall(EPSGetInterval(eps,&int0,&int1));
    164:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Found %" PetscInt_FMT " eigenvalues in interval [%g,%g]\n",nev,(double)int0,(double)int1));

    166:   if (showinertia) {
    167:     PetscCall(EPSKrylovSchurGetInertias(eps,&k,&shifts,&inertias));
    168:     PetscCall(PetscPrintf(PETSC_COMM_WORLD," Used %" PetscInt_FMT " shifts (inertia):\n",k));
    169:     for (i=0;i<k;i++) PetscCall(PetscPrintf(PETSC_COMM_WORLD," .. %g (%" PetscInt_FMT ")\n",(double)shifts[i],inertias[i]));
    170:     PetscCall(PetscFree(shifts));
    171:     PetscCall(PetscFree(inertias));
    172:   }

    174:   PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));

    176:   if (size>1) {
    177:     PetscCall(EPSKrylovSchurGetSubcommInfo(eps,&k,&nval,&v));
    178:     PetscCall(PetscMalloc1(nval,&evals));
    179:     for (i=0;i<nval;i++) {
    180:       PetscCall(EPSKrylovSchurGetSubcommPairs(eps,i,&lambda,v));
    181:       evals[i] = PetscRealPart(lambda);
    182:     }
    183:     PetscCall(PetscFormatRealArray(vlist,sizeof(vlist),"%f",nval,evals));
    184:     PetscCall(PetscSynchronizedPrintf(PETSC_COMM_WORLD," Process %d has worked in sub-interval %" PetscInt_FMT ", containing %" PetscInt_FMT " eigenvalues: %s\n",(int)rank,k,nval,vlist));
    185:     PetscCall(PetscSynchronizedFlush(PETSC_COMM_WORLD,PETSC_STDOUT));
    186:     PetscCall(VecDestroy(&v));
    187:     PetscCall(PetscFree(evals));

    189:     PetscCall(EPSKrylovSchurGetSubcommMats(eps,&As,&Bs));
    190:     PetscCall(MatGetLocalSize(A,&nloc,NULL));
    191:     PetscCall(MatGetLocalSize(As,&nlocs,&mlocs));
    192:     PetscCall(PetscSynchronizedPrintf(PETSC_COMM_WORLD," Process %d owns %" PetscInt_FMT " rows of the global matrices, and %" PetscInt_FMT " rows in the subcommunicator\n",(int)rank,nloc,nlocs));
    193:     PetscCall(PetscSynchronizedFlush(PETSC_COMM_WORLD,PETSC_STDOUT));

    195:     /* modify A on subcommunicators */
    196:     PetscCall(MatCreate(PetscObjectComm((PetscObject)As),&Au));
    197:     PetscCall(MatSetSizes(Au,nlocs,mlocs,N,N));
    198:     PetscCall(MatSetFromOptions(Au));
    199:     PetscCall(MatGetOwnershipRange(Au,&Istart,&Iend));
    200:     for (II=Istart;II<Iend;II++) PetscCall(MatSetValue(Au,II,II,0.5,INSERT_VALUES));
    201:     PetscCall(MatAssemblyBegin(Au,MAT_FINAL_ASSEMBLY));
    202:     PetscCall(MatAssemblyEnd(Au,MAT_FINAL_ASSEMBLY));
    203:     PetscCall(PetscPrintf(PETSC_COMM_WORLD," Updating internal matrices\n"));
    204:     PetscCall(EPSKrylovSchurUpdateSubcommMats(eps,1.1,-5.0,Au,1.0,0.0,NULL,DIFFERENT_NONZERO_PATTERN,PETSC_TRUE));
    205:     PetscCall(MatDestroy(&Au));
    206:     PetscCall(EPSSolve(eps));
    207:     PetscCall(EPSGetDimensions(eps,&nev,NULL,NULL));
    208:     PetscCall(EPSGetInterval(eps,&int0,&int1));
    209:     PetscCall(PetscPrintf(PETSC_COMM_WORLD," After update, found %" PetscInt_FMT " eigenvalues in interval [%g,%g]\n",nev,(double)int0,(double)int1));
    210:   }
    211:   PetscCall(EPSDestroy(&eps));
    212:   PetscCall(MatDestroy(&A));
    213:   PetscCall(MatDestroy(&B));
    214:   PetscCall(SlepcFinalize());
    215:   return 0;
    216: }

    218: /*TEST

    220:    test:
    221:       suffix: 1
    222:       nsize: 2
    223:       args: -showinertia 0 -log_exclude eps,st,rg,bv,ds
    224:       requires: !single

    226:    test:
    227:       suffix: 2
    228:       nsize: 1
    229:       args: -showinertia 0 -log_exclude eps,st,rg,bv,ds
    230:       requires: !single

    232: TEST*/