Date: 2022-08-09T09:05:39+00:00

Actual source code: test38.c
slepc-3.17.2 2022-08-09
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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[] = "Test EPSLYAPII interface functions.\n\n"
     12:   "Based on ex2.\n"
     13:   "The command line options are:\n"
     14:   "  -n <n>, where <n> = number of grid subdivisions in x dimension.\n"
     15:   "  -m <m>, where <m> = number of grid subdivisions in y dimension.\n"
     16:   "  -shift <sigma>, where <sigma> = shift of origin.\n\n";

     18: #include <slepceps.h>

     20: int main(int argc,char **argv)
     21: {
     22:   Mat            A;
     23:   EPS            eps;
     24:   PetscInt       N,n=10,m,Istart,Iend,II,i,j,rkl,rkc;
     25:   PetscBool      flag,terse;
     26:   PetscReal      sigma=8.0;

     28:   SlepcInitialize(&argc,&argv,(char*)0,help);
     29:   PetscOptionsGetReal(NULL,NULL,"-shift",&sigma,NULL);
     30:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     31:   PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag);
     32:   if (!flag) m=n;
     33:   N = n*m;
     34:   PetscPrintf(PETSC_COMM_WORLD,"\nShifted 2-D Laplacian Eigenproblem, N=%" PetscInt_FMT " (%" PetscInt_FMT "x%" PetscInt_FMT " grid) sigma=%.1f\n\n",N,n,m,(double)sigma);

     36:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     37:                     Create the 2-D Laplacian
     38:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

     56:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     57:                 Create the eigensolver and set various options
     58:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     60:   EPSCreate(PETSC_COMM_WORLD,&eps);
     61:   EPSSetOperators(eps,A,NULL);
     62:   EPSSetProblemType(eps,EPS_HEP);
     63:   EPSSetWhichEigenpairs(eps,EPS_LARGEST_REAL);
     64:   EPSSetType(eps,EPSLYAPII);
     65:   EPSSetFromOptions(eps);

     67:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     68:                 Solve the problem and display the solution
     69:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     71:   EPSSolve(eps);

     73:   /* print solver information */
     74:   PetscObjectTypeCompare((PetscObject)eps,EPSLYAPII,&flag);
     75:   if (flag) {
     76:     EPSLyapIIGetRanks(eps,&rkc,&rkl);
     77:     PetscPrintf(PETSC_COMM_WORLD," EPSLYAPII ranks: for Lyapunov solver=%" PetscInt_FMT ", after compression=%" PetscInt_FMT "\n\n",rkl,rkc);
     78:   }

     80:   PetscOptionsHasName(NULL,NULL,"-terse",&terse);
     81:   if (terse) EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
     82:   else {
     83:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
     84:     EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD);
     85:     EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
     86:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
     87:   }

     89:   EPSDestroy(&eps);
     90:   MatDestroy(&A);
     91:   SlepcFinalize();
     92:   return 0;
     93: }

     95: /*TEST

     97:    test:
     98:       args: -eps_view -terse
     99:       filter: grep -v tolerance | sed -e "s/symmetric/hermitian/"

    101: TEST*/