Date: 2023-11-27T17:19:08+00:00

Actual source code: ex38.c
slepc-3.20.1 2023-11-27
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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: */

     11: static char help[] = "Spectrum slicing on quadratic symmetric eigenproblem.\n\n"
     12:   "The command line options are:\n"
     13:   "  -n <n> ... dimension of the matrices.\n\n";

     15: #include <slepcpep.h>

     17: int main(int argc,char **argv)
     18: {
     19:   Mat            M,C,K,A[3]; /* problem matrices */
     20:   PEP            pep;        /* polynomial eigenproblem solver context */
     21:   ST             st;         /* spectral transformation context */
     22:   KSP            ksp;
     23:   PC             pc;
     24:   PEPType        type;
     25:   PetscBool      show=PETSC_FALSE,terse;
     26:   PetscInt       n=100,Istart,Iend,nev,i,*inertias,ns;
     27:   PetscReal      mu=1,tau=10,kappa=5,inta,intb,*shifts;

     29:   PetscFunctionBeginUser;
     30:   PetscCall(SlepcInitialize(&argc,&argv,(char*)0,help));

     32:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
     33:   PetscCall(PetscOptionsGetBool(NULL,NULL,"-show_inertias",&show,NULL));
     34:   PetscCall(PetscOptionsHasName(NULL,NULL,"-terse",&terse));
     35:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nSpectrum slicing on PEP, n=%" PetscInt_FMT "\n\n",n));

     37:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     38:      Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
     39:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     41:   /* K is a tridiagonal */
     42:   PetscCall(MatCreate(PETSC_COMM_WORLD,&K));
     43:   PetscCall(MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,n,n));
     44:   PetscCall(MatSetFromOptions(K));
     45:   PetscCall(MatSetUp(K));

     47:   PetscCall(MatGetOwnershipRange(K,&Istart,&Iend));
     48:   for (i=Istart;i<Iend;i++) {
     49:     if (i>0) PetscCall(MatSetValue(K,i,i-1,-kappa,INSERT_VALUES));
     50:     PetscCall(MatSetValue(K,i,i,kappa*3.0,INSERT_VALUES));
     51:     if (i<n-1) PetscCall(MatSetValue(K,i,i+1,-kappa,INSERT_VALUES));
     52:   }

     54:   PetscCall(MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY));
     55:   PetscCall(MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY));

     57:   /* C is a tridiagonal */
     58:   PetscCall(MatCreate(PETSC_COMM_WORLD,&C));
     59:   PetscCall(MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n));
     60:   PetscCall(MatSetFromOptions(C));
     61:   PetscCall(MatSetUp(C));

     63:   PetscCall(MatGetOwnershipRange(C,&Istart,&Iend));
     64:   for (i=Istart;i<Iend;i++) {
     65:     if (i>0) PetscCall(MatSetValue(C,i,i-1,-tau,INSERT_VALUES));
     66:     PetscCall(MatSetValue(C,i,i,tau*3.0,INSERT_VALUES));
     67:     if (i<n-1) PetscCall(MatSetValue(C,i,i+1,-tau,INSERT_VALUES));
     68:   }

     70:   PetscCall(MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY));
     71:   PetscCall(MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY));

     73:   /* M is a diagonal matrix */
     74:   PetscCall(MatCreate(PETSC_COMM_WORLD,&M));
     75:   PetscCall(MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n));
     76:   PetscCall(MatSetFromOptions(M));
     77:   PetscCall(MatSetUp(M));
     78:   PetscCall(MatGetOwnershipRange(M,&Istart,&Iend));
     79:   for (i=Istart;i<Iend;i++) PetscCall(MatSetValue(M,i,i,mu,INSERT_VALUES));
     80:   PetscCall(MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY));
     81:   PetscCall(MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY));

     83:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     84:                 Create the eigensolver and solve the problem
     85:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     87:   /*
     88:      Create eigensolver context
     89:   */
     90:   PetscCall(PEPCreate(PETSC_COMM_WORLD,&pep));

     92:   /*
     93:      Set operators and set problem type
     94:   */
     95:   A[0] = K; A[1] = C; A[2] = M;
     96:   PetscCall(PEPSetOperators(pep,3,A));
     97:   PetscCall(PEPSetProblemType(pep,PEP_HYPERBOLIC));

     99:   /*
    100:      Set interval for spectrum slicing
    101:   */
    102:   inta = -11.3;
    103:   intb = -9.5;
    104:   PetscCall(PEPSetInterval(pep,inta,intb));
    105:   PetscCall(PEPSetWhichEigenpairs(pep,PEP_ALL));

    107:   /*
    108:      Spectrum slicing requires STOAR
    109:   */
    110:   PetscCall(PEPSetType(pep,PEPSTOAR));

    112:   /*
    113:      Set shift-and-invert with Cholesky; select MUMPS if available
    114:   */
    115:   PetscCall(PEPGetST(pep,&st));
    116:   PetscCall(STSetType(st,STSINVERT));

    118:   PetscCall(STGetKSP(st,&ksp));
    119:   PetscCall(KSPSetType(ksp,KSPPREONLY));
    120:   PetscCall(KSPGetPC(ksp,&pc));
    121:   PetscCall(PCSetType(pc,PCCHOLESKY));

    123:   /*
    124:      Use MUMPS if available.
    125:      Note that in complex scalars we cannot use MUMPS for spectrum slicing,
    126:      because MatGetInertia() is not available in that case.
    127:   */
    128: #if defined(PETSC_HAVE_MUMPS) && !defined(PETSC_USE_COMPLEX)
    129:   PetscCall(PEPSTOARSetDetectZeros(pep,PETSC_TRUE));  /* enforce zero detection */
    130:   PetscCall(PCFactorSetMatSolverType(pc,MATSOLVERMUMPS));
    131:   /*
    132:      Add several MUMPS options (see ex43.c for a better way of setting them in program):
    133:      '-st_mat_mumps_icntl_13 1': turn off ScaLAPACK for matrix inertia
    134:      '-st_mat_mumps_icntl_24 1': detect null pivots in factorization (for the case that a shift is equal to an eigenvalue)
    135:      '-st_mat_mumps_cntl_3 <tol>': a tolerance used for null pivot detection (must be larger than machine epsilon)

    137:      Note: depending on the interval, it may be necessary also to increase the workspace:
    138:      '-st_mat_mumps_icntl_14 <percentage>': increase workspace with a percentage (50, 100 or more)
    139:   */
    140:   PetscCall(PetscOptionsInsertString(NULL,"-st_mat_mumps_icntl_13 1 -st_mat_mumps_icntl_24 1 -st_mat_mumps_cntl_3 1e-12"));
    141: #endif

    143:   /*
    144:      Set solver parameters at runtime
    145:   */
    146:   PetscCall(PEPSetFromOptions(pep));

    148:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    149:                       Solve the eigensystem
    150:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
    151:   PetscCall(PEPSetUp(pep));
    152:   if (show) {
    153:     PetscCall(PEPSTOARGetInertias(pep,&ns,&shifts,&inertias));
    154:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Subintervals (after setup):\n"));
    155:     for (i=0;i<ns;i++) PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Shift %g  Inertia %" PetscInt_FMT " \n",(double)shifts[i],inertias[i]));
    156:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\n"));
    157:     PetscCall(PetscFree(shifts));
    158:     PetscCall(PetscFree(inertias));
    159:   }
    160:   PetscCall(PEPSolve(pep));
    161:   if (show && !terse) {
    162:     PetscCall(PEPSTOARGetInertias(pep,&ns,&shifts,&inertias));
    163:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"All shifts (after solve):\n"));
    164:     for (i=0;i<ns;i++) PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Shift %g  Inertia %" PetscInt_FMT " \n",(double)shifts[i],inertias[i]));
    165:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\n"));
    166:     PetscCall(PetscFree(shifts));
    167:     PetscCall(PetscFree(inertias));
    168:   }

    170:   /*
    171:      Show eigenvalues in interval and print solution
    172:   */
    173:   PetscCall(PEPGetType(pep,&type));
    174:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type));
    175:   PetscCall(PEPGetDimensions(pep,&nev,NULL,NULL));
    176:   PetscCall(PEPGetInterval(pep,&inta,&intb));
    177:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," %" PetscInt_FMT " eigenvalues found in [%g, %g]\n",nev,(double)inta,(double)intb));

    179:   /*
    180:      Show detailed info unless -terse option is given by user
    181:    */
    182:   if (terse) PetscCall(PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL));
    183:   else {
    184:     PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL));
    185:     PetscCall(PEPConvergedReasonView(pep,PETSC_VIEWER_STDOUT_WORLD));
    186:     PetscCall(PEPErrorView(pep,PEP_ERROR_BACKWARD,PETSC_VIEWER_STDOUT_WORLD));
    187:     PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
    188:   }

    190:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    191:                     Clean up
    192:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
    193:   PetscCall(PEPDestroy(&pep));
    194:   PetscCall(MatDestroy(&M));
    195:   PetscCall(MatDestroy(&C));
    196:   PetscCall(MatDestroy(&K));
    197:   PetscCall(SlepcFinalize());
    198:   return 0;
    199: }

    201: /*TEST

    203:    testset:
    204:       requires: !single
    205:       args: -show_inertias -terse
    206:       output_file: output/ex38_1.out
    207:       test:
    208:          suffix: 1
    209:          requires: !complex
    210:       test:
    211:          suffix: 1_complex
    212:          requires: complex !mumps

    214:    test:
    215:       suffix: 2
    216:       args: -pep_interval 0,2

    218: TEST*/