Date: 2026-01-20T11:35:45+00:00

Actual source code: ex7.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[] = "Solves a generalized eigensystem Ax=kBx with matrices loaded from a file.\n\n"
     12:   "The command line options are:\n"
     13:   "  -f1 <filename> -f2 <filename>, PETSc binary files containing A and B.\n"
     14:   "  -evecs <filename>, output file to save computed eigenvectors.\n"
     15:   "  -ninitial <nini>, number of user-provided initial guesses.\n"
     16:   "  -finitial <filename>, binary file containing <nini> vectors.\n"
     17:   "  -nconstr <ncon>, number of user-provided constraints.\n"
     18:   "  -fconstr <filename>, binary file containing <ncon> vectors.\n\n";

     20: #include <slepceps.h>

     22: int main(int argc,char **argv)
     23: {
     24:   Mat            A,B;             /* matrices */
     25:   EPS            eps;             /* eigenproblem solver context */
     26:   ST             st;
     27:   KSP            ksp;
     28:   EPSType        type;
     29:   PetscReal      tol;
     30:   Vec            xr,xi,*Iv,*Cv;
     31:   PetscInt       nev,maxit,i,its,lits,nconv,nini=0,ncon=0;
     32:   char           filename[PETSC_MAX_PATH_LEN];
     33:   PetscViewer    viewer;
     34:   PetscBool      flg,evecs,ishermitian,terse;

     36:   PetscFunctionBeginUser;
     37:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));

     39:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     40:         Load the matrices that define the eigensystem, Ax=kBx
     41:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     43:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nGeneralized eigenproblem stored in file.\n\n"));
     44:   PetscCall(PetscOptionsGetString(NULL,NULL,"-f1",filename,sizeof(filename),&flg));
     45:   PetscCheck(flg,PETSC_COMM_WORLD,PETSC_ERR_USER_INPUT,"Must indicate a file name for matrix A with the -f1 option");

     47: #if defined(PETSC_USE_COMPLEX)
     48:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Reading COMPLEX matrices from binary files...\n"));
     49: #else
     50:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Reading REAL matrices from binary files...\n"));
     51: #endif
     52:   PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer));
     53:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
     54:   PetscCall(MatSetFromOptions(A));
     55:   PetscCall(MatLoad(A,viewer));
     56:   PetscCall(PetscViewerDestroy(&viewer));

     58:   PetscCall(PetscOptionsGetString(NULL,NULL,"-f2",filename,sizeof(filename),&flg));
     59:   if (flg) {
     60:     PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer));
     61:     PetscCall(MatCreate(PETSC_COMM_WORLD,&B));
     62:     PetscCall(MatSetFromOptions(B));
     63:     PetscCall(MatLoad(B,viewer));
     64:     PetscCall(PetscViewerDestroy(&viewer));
     65:   } else {
     66:     PetscCall(PetscPrintf(PETSC_COMM_WORLD," Matrix B was not provided, setting B=I\n\n"));
     67:     B = NULL;
     68:   }

     70:   PetscCall(MatCreateVecs(A,NULL,&xr));
     71:   PetscCall(MatCreateVecs(A,NULL,&xi));

     73:   /*
     74:      Read user constraints if available
     75:   */
     76:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-nconstr",&ncon,&flg));
     77:   if (flg) {
     78:     PetscCheck(ncon>0,PETSC_COMM_WORLD,PETSC_ERR_USER_INPUT,"The number of constraints must be >0");
     79:     PetscCall(PetscOptionsGetString(NULL,NULL,"-fconstr",filename,sizeof(filename),&flg));
     80:     PetscCheck(flg,PETSC_COMM_WORLD,PETSC_ERR_USER_INPUT,"Must specify the name of the file storing the constraints");
     81:     PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer));
     82:     PetscCall(VecDuplicateVecs(xr,ncon,&Cv));
     83:     for (i=0;i<ncon;i++) PetscCall(VecLoad(Cv[i],viewer));
     84:     PetscCall(PetscViewerDestroy(&viewer));
     85:   }

     87:   /*
     88:      Read initial guesses if available
     89:   */
     90:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-ninitial",&nini,&flg));
     91:   if (flg) {
     92:     PetscCheck(nini>0,PETSC_COMM_WORLD,PETSC_ERR_USER_INPUT,"The number of initial vectors must be >0");
     93:     PetscCall(PetscOptionsGetString(NULL,NULL,"-finitial",filename,sizeof(filename),&flg));
     94:     PetscCheck(flg,PETSC_COMM_WORLD,PETSC_ERR_USER_INPUT,"Must specify the name of the file containing the initial vectors");
     95:     PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer));
     96:     PetscCall(VecDuplicateVecs(xr,nini,&Iv));
     97:     for (i=0;i<nini;i++) PetscCall(VecLoad(Iv[i],viewer));
     98:     PetscCall(PetscViewerDestroy(&viewer));
     99:   }

    101:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    102:                 Create the eigensolver and set various options
    103:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    105:   /*
    106:      Create eigensolver context
    107:   */
    108:   PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));

    110:   /*
    111:      Set operators. In this case, it is a generalized eigenvalue problem
    112:   */
    113:   PetscCall(EPSSetOperators(eps,A,B));

    115:   /*
    116:      If the user provided initial guesses or constraints, pass them here
    117:   */
    118:   PetscCall(EPSSetInitialSpace(eps,nini,Iv));
    119:   PetscCall(EPSSetDeflationSpace(eps,ncon,Cv));

    121:   /*
    122:      Set solver parameters at runtime
    123:   */
    124:   PetscCall(EPSSetFromOptions(eps));

    126:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    127:                       Solve the eigensystem
    128:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    130:   PetscCall(EPSSolve(eps));

    132:   /*
    133:      Optional: Get some information from the solver and display it
    134:   */
    135:   PetscCall(EPSGetIterationNumber(eps,&its));
    136:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Number of iterations of the method: %" PetscInt_FMT "\n",its));
    137:   PetscCall(EPSGetST(eps,&st));
    138:   PetscCall(STGetKSP(st,&ksp));
    139:   PetscCall(KSPGetTotalIterations(ksp,&lits));
    140:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Number of linear iterations of the method: %" PetscInt_FMT "\n",lits));
    141:   PetscCall(EPSGetType(eps,&type));
    142:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type));
    143:   PetscCall(EPSGetDimensions(eps,&nev,NULL,NULL));
    144:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %" PetscInt_FMT "\n",nev));
    145:   PetscCall(EPSGetTolerances(eps,&tol,&maxit));
    146:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Stopping condition: tol=%.4g, maxit=%" PetscInt_FMT "\n",(double)tol,maxit));

    148:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    149:                     Display solution and clean up
    150:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    152:   /*
    153:      Show detailed info unless -terse option is given by user
    154:    */
    155:   PetscCall(PetscOptionsHasName(NULL,NULL,"-terse",&terse));
    156:   if (terse) PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));
    157:   else {
    158:     PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL));
    159:     PetscCall(EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD));
    160:     PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD));
    161:     PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
    162:   }

    164:   /*
    165:      Save eigenvectors, if requested
    166:   */
    167:   PetscCall(PetscOptionsGetString(NULL,NULL,"-evecs",filename,sizeof(filename),&evecs));
    168:   PetscCall(EPSGetConverged(eps,&nconv));
    169:   if (nconv>0 && evecs) {
    170:     PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_WRITE,&viewer));
    171:     PetscCall(EPSIsHermitian(eps,&ishermitian));
    172:     for (i=0;i<nconv;i++) {
    173:       PetscCall(EPSGetEigenvector(eps,i,xr,xi));
    174:       PetscCall(VecView(xr,viewer));
    175: #if !defined(PETSC_USE_COMPLEX)
    176:       if (!ishermitian) PetscCall(VecView(xi,viewer));
    177: #endif
    178:     }
    179:     PetscCall(PetscViewerDestroy(&viewer));
    180:   }

    182:   /*
    183:      Free work space
    184:   */
    185:   PetscCall(EPSDestroy(&eps));
    186:   PetscCall(MatDestroy(&A));
    187:   PetscCall(MatDestroy(&B));
    188:   PetscCall(VecDestroy(&xr));
    189:   PetscCall(VecDestroy(&xi));
    190:   if (nini > 0) PetscCall(VecDestroyVecs(nini,&Iv));
    191:   if (ncon > 0) PetscCall(VecDestroyVecs(ncon,&Cv));
    192:   PetscCall(SlepcFinalize());
    193:   return 0;
    194: }

    196: /*TEST

    198:    test:
    199:       suffix: 1
    200:       args: -f1 ${SLEPC_DIR}/share/slepc/datafiles/matrices/bfw62a.petsc -f2 ${SLEPC_DIR}/share/slepc/datafiles/matrices/bfw62b.petsc -eps_nev 4 -terse
    201:       requires: double !complex !defined(PETSC_USE_64BIT_INDICES)

    203:    test:
    204:       suffix: ciss_1
    205:       args: -f1 ${DATAFILESPATH}/matrices/complex/mhd1280a.petsc -f2 ${DATAFILESPATH}/matrices/complex/mhd1280b.petsc -eps_type ciss -eps_ciss_usest 0 -eps_ciss_quadrule chebyshev -rg_type ring -rg_ring_center 0 -rg_ring_radius .49 -rg_ring_width 0.2 -rg_ring_startangle .25 -rg_ring_endangle .49 -terse -eps_max_it 1
    206:       requires: double complex datafilespath !defined(PETSC_USE_64BIT_INDICES)
    207:       timeoutfactor: 2

    209:    test:
    210:       suffix: 3 # test problem (A,A)
    211:       args: -f1 ${SLEPC_DIR}/share/slepc/datafiles/matrices/bfw62a.petsc -f2 ${SLEPC_DIR}/share/slepc/datafiles/matrices/bfw62a.petsc -eps_nev 4 -terse
    212:       requires: double !complex !defined(PETSC_USE_64BIT_INDICES)

    214: TEST*/