Date: 2022-10-01T06:40:27+00:00

Actual source code: test13.c
slepc-3.18.0 2022-10-01
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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[] = "Solve a quadratic problem with CISS.\n\n"
     12:   "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 <slepcpep.h>

     18: int main(int argc,char **argv)
     19: {
     20:   Mat               M,C,K,A[3];
     21:   PEP               pep;
     22:   RG                rg;
     23:   KSP               *ksp;
     24:   PC                pc;
     25:   PEPCISSExtraction ext;
     26:   PetscInt          N,n=10,m,Istart,Iend,II,i,j,nsolve;
     27:   PetscBool         flg;

     30:   SlepcInitialize(&argc,&argv,(char*)0,help);
     31:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     32:   PetscOptionsGetInt(NULL,NULL,"-m",&m,&flg);
     33:   if (!flg) m=n;
     34:   N = n*m;
     35:   PetscPrintf(PETSC_COMM_WORLD,"\nQuadratic Eigenproblem, N=%" PetscInt_FMT " (%" PetscInt_FMT "x%" PetscInt_FMT " grid)\n\n",N,n,m);

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

     41:   /* K is the 2-D Laplacian */
     42:   MatCreate(PETSC_COMM_WORLD,&K);
     43:   MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,N,N);
     44:   MatSetFromOptions(K);
     45:   MatSetUp(K);
     46:   MatGetOwnershipRange(K,&Istart,&Iend);
     47:   for (II=Istart;II<Iend;II++) {
     48:     i = II/n; j = II-i*n;
     49:     if (i>0) MatSetValue(K,II,II-n,-1.0,INSERT_VALUES);
     50:     if (i<m-1) MatSetValue(K,II,II+n,-1.0,INSERT_VALUES);
     51:     if (j>0) MatSetValue(K,II,II-1,-1.0,INSERT_VALUES);
     52:     if (j<n-1) MatSetValue(K,II,II+1,-1.0,INSERT_VALUES);
     53:     MatSetValue(K,II,II,4.0,INSERT_VALUES);
     54:   }
     55:   MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY);
     56:   MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY);

     58:   /* C is the 1-D Laplacian on horizontal lines */
     59:   MatCreate(PETSC_COMM_WORLD,&C);
     60:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,N,N);
     61:   MatSetFromOptions(C);
     62:   MatSetUp(C);
     63:   MatGetOwnershipRange(C,&Istart,&Iend);
     64:   for (II=Istart;II<Iend;II++) {
     65:     i = II/n; j = II-i*n;
     66:     if (j>0) MatSetValue(C,II,II-1,-1.0,INSERT_VALUES);
     67:     if (j<n-1) MatSetValue(C,II,II+1,-1.0,INSERT_VALUES);
     68:     MatSetValue(C,II,II,2.0,INSERT_VALUES);
     69:   }
     70:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
     71:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

     73:   /* M is a diagonal matrix */
     74:   MatCreate(PETSC_COMM_WORLD,&M);
     75:   MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,N,N);
     76:   MatSetFromOptions(M);
     77:   MatSetUp(M);
     78:   MatGetOwnershipRange(M,&Istart,&Iend);
     79:   for (II=Istart;II<Iend;II++) MatSetValue(M,II,II,(PetscReal)(II+1),INSERT_VALUES);
     80:   MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
     81:   MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);

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

     87:   PEPCreate(PETSC_COMM_WORLD,&pep);
     88:   A[0] = K; A[1] = C; A[2] = M;
     89:   PEPSetOperators(pep,3,A);
     90:   PEPSetProblemType(pep,PEP_GENERAL);

     92:   /* customize polynomial eigensolver; set runtime options */
     93:   PEPSetType(pep,PEPCISS);
     94:   PEPGetRG(pep,&rg);
     95:   RGSetType(rg,RGELLIPSE);
     96:   RGEllipseSetParameters(rg,PetscCMPLX(-0.1,0.3),0.1,0.25);
     97:   PEPCISSSetSizes(pep,24,PETSC_DEFAULT,PETSC_DEFAULT,1,PETSC_DEFAULT,PETSC_TRUE);
     98:   PEPCISSGetKSPs(pep,&nsolve,&ksp);
     99:   for (i=0;i<nsolve;i++) {
    100:     KSPSetTolerances(ksp[i],1e-12,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);
    101:     KSPSetType(ksp[i],KSPPREONLY);
    102:     KSPGetPC(ksp[i],&pc);
    103:     PCSetType(pc,PCLU);
    104:   }
    105:   PEPSetFromOptions(pep);

    107:   /* solve */
    108:   PetscObjectTypeCompare((PetscObject)pep,PEPCISS,&flg);
    109:   if (flg) {
    110:     PEPCISSGetExtraction(pep,&ext);
    111:     PetscPrintf(PETSC_COMM_WORLD," Running CISS with %" PetscInt_FMT " KSP solvers (%s extraction)\n",nsolve,PEPCISSExtractions[ext]);
    112:   }
    113:   PEPSolve(pep);

    115:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    116:                     Display solution and clean up
    117:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    119:   PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL);
    120:   PEPDestroy(&pep);
    121:   MatDestroy(&M);
    122:   MatDestroy(&C);
    123:   MatDestroy(&K);
    124:   SlepcFinalize();
    125:   return 0;
    126: }

    128: /*TEST

    130:    build:
    131:       requires: complex

    133:    test:
    134:       suffix: 1
    135:       requires: complex

    137: TEST*/