Date: 2024-10-28T09:14:05+00:00

Actual source code: test13.c
slepc-3.22.1 2024-10-28
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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;

     29:   PetscFunctionBeginUser;
     30:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
     31:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
     32:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-m",&m,&flg));
     33:   if (!flg) m=n;
     34:   N = n*m;
     35:   PetscCall(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:   PetscCall(MatCreate(PETSC_COMM_WORLD,&K));
     43:   PetscCall(MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,N,N));
     44:   PetscCall(MatSetFromOptions(K));
     45:   PetscCall(MatGetOwnershipRange(K,&Istart,&Iend));
     46:   for (II=Istart;II<Iend;II++) {
     47:     i = II/n; j = II-i*n;
     48:     if (i>0) PetscCall(MatSetValue(K,II,II-n,-1.0,INSERT_VALUES));
     49:     if (i<m-1) PetscCall(MatSetValue(K,II,II+n,-1.0,INSERT_VALUES));
     50:     if (j>0) PetscCall(MatSetValue(K,II,II-1,-1.0,INSERT_VALUES));
     51:     if (j<n-1) PetscCall(MatSetValue(K,II,II+1,-1.0,INSERT_VALUES));
     52:     PetscCall(MatSetValue(K,II,II,4.0,INSERT_VALUES));
     53:   }
     54:   PetscCall(MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY));
     55:   PetscCall(MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY));

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

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

     80:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     81:              Create the eigensolver and solve the eigensystem
     82:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     84:   PetscCall(PEPCreate(PETSC_COMM_WORLD,&pep));
     85:   A[0] = K; A[1] = C; A[2] = M;
     86:   PetscCall(PEPSetOperators(pep,3,A));
     87:   PetscCall(PEPSetProblemType(pep,PEP_GENERAL));

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

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

    112:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    113:                     Display solution and clean up
    114:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    116:   PetscCall(PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL));
    117:   PetscCall(PEPDestroy(&pep));
    118:   PetscCall(MatDestroy(&M));
    119:   PetscCall(MatDestroy(&C));
    120:   PetscCall(MatDestroy(&K));
    121:   PetscCall(SlepcFinalize());
    122:   return 0;
    123: }

    125: /*TEST

    127:    build:
    128:       requires: complex

    130:    test:
    131:       suffix: 1
    132:       requires: complex

    134: TEST*/