Date: 2022-03-31T15:29:17+00:00

Actual source code: ex49.c
slepc-3.17.0 2022-03-31
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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:   SlepcInitialize(&argc,&argv,(char*)0,help);

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

     34:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     35:           Compute the problem matrices A and B
     36:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

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

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

     69:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     70:           Compute sparser approximations A0 and B0
     71:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     73:   MatCreate(PETSC_COMM_WORLD,&A0);
     74:   MatSetSizes(A0,PETSC_DECIDE,PETSC_DECIDE,N,N);
     75:   MatSetFromOptions(A0);
     76:   MatSetUp(A0);

     78:   MatCreate(PETSC_COMM_WORLD,&B0);
     79:   MatSetSizes(B0,PETSC_DECIDE,PETSC_DECIDE,N,N);
     80:   MatSetFromOptions(B0);
     81:   MatSetUp(B0);

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

    100:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    101:                 Create the eigensolver and set various options
    102:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

    115:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    116:                  Solve the eigensystem and display solution
    117:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    119:   EPSSolve(eps);

    121:   /* show detailed info unless -terse option is given by user */
    122:   PetscOptionsHasName(NULL,NULL,"-terse",&terse);
    123:   if (terse) EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
    124:   else {
    125:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
    126:     EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD);
    127:     EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
    128:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
    129:   }
    130:   EPSDestroy(&eps);
    131:   MatDestroy(&A);
    132:   MatDestroy(&B);
    133:   MatDestroy(&A0);
    134:   MatDestroy(&B0);
    135:   SlepcFinalize();
    136:   return 0;
    137: }

    139: /*TEST

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

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

    169: TEST*/