Date: 2024-12-02T08:57:11+00:00

Actual source code: ex49.c
slepc-3.22.2 2024-12-02
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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[] = "User-defined split preconditioner when solving a generalized eigenproblem.\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 <slepceps.h>

     18: int main(int argc,char **argv)
     19: {
     20:   Mat            A,B,A0,B0,mats[2]; /* problem matrices and sparser approximations */
     21:   EPS            eps;               /* eigenproblem solver context */
     22:   ST             st;
     23:   PetscInt       N,n=24,m,Istart,Iend,II,i,j;
     24:   PetscBool      flag,terse;

     26:   PetscFunctionBeginUser;
     27:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));

     29:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
     30:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag));
     31:   if (!flag) m=n;
     32:   N = n*m;
     33:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nGHEP with split preconditioner, N=%" PetscInt_FMT " (%" PetscInt_FMT "x%" PetscInt_FMT " grid)\n\n",N,n,m));

     35:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     36:           Compute the problem matrices A and B
     37:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     39:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
     40:   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,N,N));
     41:   PetscCall(MatSetFromOptions(A));

     43:   PetscCall(MatCreate(PETSC_COMM_WORLD,&B));
     44:   PetscCall(MatSetSizes(B,PETSC_DECIDE,PETSC_DECIDE,N,N));
     45:   PetscCall(MatSetFromOptions(B));

     47:   PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
     48:   for (II=Istart;II<Iend;II++) {
     49:     i = II/n; j = II-i*n;
     50:     if (i>0) PetscCall(MatSetValue(A,II,II-n,-0.2,INSERT_VALUES));
     51:     if (i<m-1) PetscCall(MatSetValue(A,II,II+n,-0.2,INSERT_VALUES));
     52:     if (j>0) PetscCall(MatSetValue(A,II,II-1,-3.0,INSERT_VALUES));
     53:     if (j<n-1) PetscCall(MatSetValue(A,II,II+1,-3.0,INSERT_VALUES));
     54:     PetscCall(MatSetValue(A,II,II,7.0,INSERT_VALUES));
     55:     PetscCall(MatSetValue(B,II,II,2.0,INSERT_VALUES));
     56:   }
     57:   if (Istart==0) {
     58:     PetscCall(MatSetValue(B,0,0,6.0,INSERT_VALUES));
     59:     PetscCall(MatSetValue(B,0,1,-1.0,INSERT_VALUES));
     60:     PetscCall(MatSetValue(B,1,0,-1.0,INSERT_VALUES));
     61:     PetscCall(MatSetValue(B,1,1,1.0,INSERT_VALUES));
     62:   }
     63:   PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
     64:   PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));
     65:   PetscCall(MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY));
     66:   PetscCall(MatAssemblyEnd(B,MAT_FINAL_ASSEMBLY));

     68:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     69:           Compute sparser approximations A0 and B0
     70:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     72:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A0));
     73:   PetscCall(MatSetSizes(A0,PETSC_DECIDE,PETSC_DECIDE,N,N));
     74:   PetscCall(MatSetFromOptions(A0));

     76:   PetscCall(MatCreate(PETSC_COMM_WORLD,&B0));
     77:   PetscCall(MatSetSizes(B0,PETSC_DECIDE,PETSC_DECIDE,N,N));
     78:   PetscCall(MatSetFromOptions(B0));

     80:   PetscCall(MatGetOwnershipRange(A0,&Istart,&Iend));
     81:   for (II=Istart;II<Iend;II++) {
     82:     i = II/n; j = II-i*n;
     83:     if (j>0) PetscCall(MatSetValue(A0,II,II-1,-3.0,INSERT_VALUES));
     84:     if (j<n-1) PetscCall(MatSetValue(A0,II,II+1,-3.0,INSERT_VALUES));
     85:     PetscCall(MatSetValue(A0,II,II,7.0,INSERT_VALUES));
     86:     PetscCall(MatSetValue(B0,II,II,2.0,INSERT_VALUES));
     87:   }
     88:   if (Istart==0) {
     89:     PetscCall(MatSetValue(B0,0,0,6.0,INSERT_VALUES));
     90:     PetscCall(MatSetValue(B0,1,1,1.0,INSERT_VALUES));
     91:   }
     92:   PetscCall(MatAssemblyBegin(A0,MAT_FINAL_ASSEMBLY));
     93:   PetscCall(MatAssemblyEnd(A0,MAT_FINAL_ASSEMBLY));
     94:   PetscCall(MatAssemblyBegin(B0,MAT_FINAL_ASSEMBLY));
     95:   PetscCall(MatAssemblyEnd(B0,MAT_FINAL_ASSEMBLY));

     97:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     98:                 Create the eigensolver and set various options
     99:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    101:   PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
    102:   PetscCall(EPSSetOperators(eps,A,B));
    103:   PetscCall(EPSSetProblemType(eps,EPS_GHEP));
    104:   PetscCall(EPSGetST(eps,&st));
    105:   PetscCall(STSetType(st,STSINVERT));
    106:   mats[0] = A0; mats[1] = B0;
    107:   PetscCall(STSetSplitPreconditioner(st,2,mats,SUBSET_NONZERO_PATTERN));
    108:   PetscCall(EPSSetTarget(eps,0.0));
    109:   PetscCall(EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE));
    110:   PetscCall(EPSSetFromOptions(eps));

    112:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    113:                  Solve the eigensystem and display solution
    114:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    116:   PetscCall(EPSSolve(eps));

    118:   /* show detailed info unless -terse option is given by user */
    119:   PetscCall(PetscOptionsHasName(NULL,NULL,"-terse",&terse));
    120:   if (terse) PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));
    121:   else {
    122:     PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL));
    123:     PetscCall(EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD));
    124:     PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD));
    125:     PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
    126:   }
    127:   PetscCall(EPSDestroy(&eps));
    128:   PetscCall(MatDestroy(&A));
    129:   PetscCall(MatDestroy(&B));
    130:   PetscCall(MatDestroy(&A0));
    131:   PetscCall(MatDestroy(&B0));
    132:   PetscCall(SlepcFinalize());
    133:   return 0;
    134: }

    136: /*TEST

    138:    testset:
    139:       args: -eps_nev 4 -terse
    140:       output_file: output/ex49_1.out
    141:       requires: !single
    142:       test:
    143:          suffix: 1
    144:       test:
    145:          suffix: 1_jd
    146:          args: -eps_type jd -st_type precond
    147:       test:
    148:          suffix: 1_lobpcg
    149:          args: -eps_type lobpcg -st_type precond -eps_smallest_real -st_shift 0.2

    151:    testset:
    152:       args: -eps_type ciss -eps_all -rg_type ellipse -rg_ellipse_center 0 -rg_ellipse_radius 0.34 -rg_ellipse_vscale .2 -st_ksp_type gmres -terse
    153:       output_file: output/ex49_2.out
    154:       test:
    155:          suffix: 2
    156:       test:
    157:          suffix: 2_nost
    158:          args: -eps_ciss_usest 0
    159:          requires: !single
    160:       test:
    161:          suffix: 2_par
    162:          nsize: 2
    163:          args: -eps_ciss_partitions 2
    164:          requires: !single

    166: TEST*/