Date: 2026-01-20T11:35:25+00:00

Actual source code: test5.c

      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 DSGHIEP.\n\n";

     13: #include <slepcds.h>

     15: int main(int argc,char **argv)
     16: {
     17:   DS             ds;
     18:   SlepcSC        sc;
     19:   PetscReal      re,im;
     20:   PetscScalar    *A,*B,*Q,*eigr,*eigi,d;
     21:   PetscInt       i,j,n=10,ld;
     22:   PetscViewer    viewer;
     23:   PetscBool      verbose,extrarow;

     25:   PetscFunctionBeginUser;
     26:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
     27:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
     28:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Solve a Dense System of type GHIEP - dimension %" PetscInt_FMT ".\n",n));
     29:   PetscCall(PetscOptionsHasName(NULL,NULL,"-verbose",&verbose));
     30:   PetscCall(PetscOptionsHasName(NULL,NULL,"-extrarow",&extrarow));

     32:   /* Create DS object */
     33:   PetscCall(DSCreate(PETSC_COMM_WORLD,&ds));
     34:   PetscCall(DSSetType(ds,DSGHIEP));
     35:   PetscCall(DSSetFromOptions(ds));
     36:   ld = n+2;  /* test leading dimension larger than n */
     37:   PetscCall(DSAllocate(ds,ld));
     38:   PetscCall(DSSetDimensions(ds,n,0,0));
     39:   PetscCall(DSSetExtraRow(ds,extrarow));

     41:   /* Set up viewer */
     42:   PetscCall(PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer));
     43:   PetscCall(PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL));
     44:   PetscCall(DSView(ds,viewer));
     45:   PetscCall(PetscViewerPopFormat(viewer));
     46:   if (verbose) PetscCall(PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB));

     48:   /* Fill with a symmetric Toeplitz matrix */
     49:   PetscCall(DSGetArray(ds,DS_MAT_A,&A));
     50:   PetscCall(DSGetArray(ds,DS_MAT_B,&B));
     51:   for (i=0;i<n;i++) A[i+i*ld]=2.0;
     52:   for (j=1;j<3;j++) {
     53:     for (i=0;i<n-j;i++) { A[i+(i+j)*ld]=1.0; A[(i+j)+i*ld]=1.0; }
     54:   }
     55:   for (j=1;j<3;j++) { A[0+j*ld]=-1.0*(j+2); A[j+0*ld]=-1.0*(j+2); }
     56:   if (extrarow) A[n+(n-1)*ld]=-1.0;
     57:   /* Signature matrix */
     58:   for (i=0;i<n;i++) B[i+i*ld]=1.0;
     59:   B[0] = -1.0;
     60:   B[n-1+(n-1)*ld] = -1.0;
     61:   PetscCall(DSRestoreArray(ds,DS_MAT_A,&A));
     62:   PetscCall(DSRestoreArray(ds,DS_MAT_B,&B));
     63:   PetscCall(DSSetState(ds,DS_STATE_RAW));
     64:   if (verbose) {
     65:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n"));
     66:     PetscCall(DSView(ds,viewer));
     67:   }

     69:   /* Solve */
     70:   PetscCall(PetscCalloc2(n,&eigr,n,&eigi));
     71:   PetscCall(DSGetSlepcSC(ds,&sc));
     72:   sc->comparison    = SlepcCompareLargestMagnitude;
     73:   sc->comparisonctx = NULL;
     74:   sc->map           = NULL;
     75:   sc->mapobj        = NULL;
     76:   PetscCall(DSSolve(ds,eigr,eigi));
     77:   PetscCall(DSSort(ds,eigr,eigi,NULL,NULL,NULL));
     78:   if (extrarow) PetscCall(DSUpdateExtraRow(ds));

     80:   if (verbose) {
     81:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n"));
     82:     PetscCall(DSView(ds,viewer));
     83:   }

     85:   /* Print eigenvalues */
     86:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Computed eigenvalues =\n"));
     87:   for (i=0;i<n;i++) {
     88: #if defined(PETSC_USE_COMPLEX)
     89:     re = PetscRealPart(eigr[i]);
     90:     im = PetscImaginaryPart(eigr[i]);
     91: #else
     92:     re = eigr[i];
     93:     im = eigi[i];
     94: #endif
     95:     if (PetscAbs(im)<1e-10) PetscCall(PetscViewerASCIIPrintf(viewer,"  %.5f\n",(double)re));
     96:     else PetscCall(PetscViewerASCIIPrintf(viewer,"  %.5f%+.5fi\n",(double)re,(double)im));
     97:   }

     99:   if (extrarow) {
    100:     /* Check that extra row is correct */
    101:     PetscCall(DSGetArray(ds,DS_MAT_A,&A));
    102:     PetscCall(DSGetArray(ds,DS_MAT_Q,&Q));
    103:     d = 0.0;
    104:     for (i=0;i<n;i++) d += A[n+i*ld]+Q[n-1+i*ld];
    105:     if (PetscAbsScalar(d)>10*PETSC_MACHINE_EPSILON) PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Warning: there is a mismatch in the extra row of %g\n",(double)PetscAbsScalar(d)));
    106:     PetscCall(DSRestoreArray(ds,DS_MAT_A,&A));
    107:     PetscCall(DSRestoreArray(ds,DS_MAT_Q,&Q));
    108:   }
    109:   PetscCall(PetscFree2(eigr,eigi));
    110:   PetscCall(DSDestroy(&ds));
    111:   PetscCall(SlepcFinalize());
    112:   return 0;
    113: }

    115: /*TEST

    117:    testset:
    118:       args: -ds_method {{0 1 2}}
    119:       filter: grep -v "solving the problem" | sed -e "s/extrarow//"
    120:       output_file: output/test5_1.out
    121:       requires: !single
    122:       test:
    123:          suffix: 1
    124:       test:
    125:          suffix: 2
    126:          args: -extrarow

    128: TEST*/