Date: 2022-10-01T06:40:04+00:00

Actual source code: ex4.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[] = "Solves a standard eigensystem Ax=kx with the matrix loaded from a file.\n"
     12:   "This example works for both real and complex numbers.\n\n"
     13:   "The command line options are:\n"
     14:   "  -file <filename>, where <filename> = matrix file in PETSc binary form.\n\n";

     16: #include <slepceps.h>

     18: int main(int argc,char **argv)
     19: {
     20:   Mat            A;               /* operator matrix */
     21:   EPS            eps;             /* eigenproblem solver context */
     22:   EPSType        type;
     23:   PetscReal      tol;
     24:   PetscInt       nev,maxit,its;
     25:   char           filename[PETSC_MAX_PATH_LEN];
     26:   PetscViewer    viewer;
     27:   PetscBool      flg,terse;

     30:   SlepcInitialize(&argc,&argv,(char*)0,help);

     32:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     33:         Load the operator matrix that defines the eigensystem, Ax=kx
     34:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     36:   PetscPrintf(PETSC_COMM_WORLD,"\nEigenproblem stored in file.\n\n");
     37:   PetscOptionsGetString(NULL,NULL,"-file",filename,sizeof(filename),&flg);

     40: #if defined(PETSC_USE_COMPLEX)
     41:   PetscPrintf(PETSC_COMM_WORLD," Reading COMPLEX matrix from a binary file...\n");
     42: #else
     43:   PetscPrintf(PETSC_COMM_WORLD," Reading REAL matrix from a binary file...\n");
     44: #endif
     45:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer);
     46:   MatCreate(PETSC_COMM_WORLD,&A);
     47:   MatSetFromOptions(A);
     48:   MatLoad(A,viewer);
     49:   PetscViewerDestroy(&viewer);

     51:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     52:                 Create the eigensolver and set various options
     53:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     55:   /*
     56:      Create eigensolver context
     57:   */
     58:   EPSCreate(PETSC_COMM_WORLD,&eps);

     60:   /*
     61:      Set operators. In this case, it is a standard eigenvalue problem
     62:   */
     63:   EPSSetOperators(eps,A,NULL);

     65:   /*
     66:      Set solver parameters at runtime
     67:   */
     68:   EPSSetFromOptions(eps);

     70:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     71:                       Solve the eigensystem
     72:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     74:   EPSSolve(eps);
     75:   EPSGetIterationNumber(eps,&its);
     76:   PetscPrintf(PETSC_COMM_WORLD," Number of iterations of the method: %" PetscInt_FMT "\n",its);

     78:   /*
     79:      Optional: Get some information from the solver and display it
     80:   */
     81:   EPSGetType(eps,&type);
     82:   PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type);
     83:   EPSGetDimensions(eps,&nev,NULL,NULL);
     84:   PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %" PetscInt_FMT "\n",nev);
     85:   EPSGetTolerances(eps,&tol,&maxit);
     86:   PetscPrintf(PETSC_COMM_WORLD," Stopping condition: tol=%.4g, maxit=%" PetscInt_FMT "\n",(double)tol,maxit);

     88:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     89:                     Display solution and clean up
     90:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     92:   /* show detailed info unless -terse option is given by user */
     93:   PetscOptionsHasName(NULL,NULL,"-terse",&terse);
     94:   if (terse) EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
     95:   else {
     96:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
     97:     EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD);
     98:     EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
     99:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
    100:   }
    101:   EPSDestroy(&eps);
    102:   MatDestroy(&A);
    103:   SlepcFinalize();
    104:   return 0;
    105: }

    107: /*TEST

    109:    test:
    110:       suffix: 1
    111:       args: -file ${SLEPC_DIR}/share/slepc/datafiles/matrices/rdb200.petsc -eps_nev 4 -terse
    112:       requires: double !complex !defined(PETSC_USE_64BIT_INDICES)

    114:    testset:
    115:       args: -file ${DATAFILESPATH}/matrices/complex/qc324.petsc -eps_type ciss -terse
    116:       requires: double complex datafilespath !defined(PETSC_USE_64BIT_INDICES)
    117:       test:
    118:          suffix: ciss_1
    119:          args: -rg_type ellipse -rg_ellipse_center -.012-.08i -rg_ellipse_radius .05
    120:       test:
    121:          suffix: ciss_2
    122:          args: -rg_type interval -rg_interval_endpoints -0.062,.038,-.13,-.03 -eps_max_it 1

    124: TEST*/