Date: 2026-03-31T13:23:14+00:00

Actual source code: test17.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 DSPEP with complex eigenvalues.\n\n";

     13: #include <slepcds.h>

     15: int main(int argc,char **argv)
     16: {
     17:   DS             ds;
     18:   SlepcSC        sc;
     19:   Mat            X;
     20:   Vec            x0;
     21:   PetscScalar    *K,*M,*wr,*wi;
     22:   PetscReal      re,im,nrm;
     23:   PetscInt       i,n=10,d=2,ld;
     24:   PetscViewer    viewer;
     25:   PetscBool      verbose;

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

     33:   /* Create DS object */
     34:   PetscCall(DSCreate(PETSC_COMM_WORLD,&ds));
     35:   PetscCall(DSSetType(ds,DSPEP));
     36:   PetscCall(DSSetFromOptions(ds));
     37:   PetscCall(DSPEPSetDegree(ds,d));

     39:   /* Set dimensions */
     40:   ld = n+2;  /* test leading dimension larger than n */
     41:   PetscCall(DSAllocate(ds,ld));
     42:   PetscCall(DSSetDimensions(ds,n,0,0));

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

     51:   /* Fill matrices */
     52:   PetscCall(DSGetArray(ds,DS_MAT_E0,&K));
     53:   for (i=0;i<n;i++) K[i+i*ld] = 2.0;
     54:   for (i=1;i<n;i++) {
     55:     K[i+(i-1)*ld] = -1.0;
     56:     K[(i-1)+i*ld] = -1.0;
     57:   }
     58:   PetscCall(DSRestoreArray(ds,DS_MAT_E0,&K));
     59:   PetscCall(DSGetArray(ds,DS_MAT_E2,&M));
     60:   for (i=0;i<n;i++) M[i+i*ld] = 1.0;
     61:   PetscCall(DSRestoreArray(ds,DS_MAT_E2,&M));

     63:   if (verbose) {
     64:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n"));
     65:     PetscCall(DSView(ds,viewer));
     66:   }

     68:   /* Solve */
     69:   PetscCall(PetscMalloc2(d*n,&wr,d*n,&wi));
     70:   PetscCall(DSGetSlepcSC(ds,&sc));
     71:   sc->comparison    = SlepcCompareLargestImaginary;
     72:   sc->comparisonctx = NULL;
     73:   sc->map           = NULL;
     74:   sc->mapobj        = NULL;
     75:   PetscCall(DSSolve(ds,wr,wi));
     76:   PetscCall(DSSort(ds,wr,wi,NULL,NULL,NULL));
     77:   if (verbose) {
     78:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n"));
     79:     PetscCall(DSView(ds,viewer));
     80:   }

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

     96:   /* Eigenvectors */
     97:   PetscCall(DSVectors(ds,DS_MAT_X,NULL,NULL));  /* all eigenvectors */
     98:   PetscCall(DSGetMat(ds,DS_MAT_X,&X));
     99:   PetscCall(MatCreateVecs(X,NULL,&x0));
    100:   PetscCall(MatGetColumnVector(X,x0,1));
    101:   PetscCall(VecNorm(x0,NORM_2,&nrm));
    102:   PetscCall(DSRestoreMat(ds,DS_MAT_X,&X));
    103:   PetscCall(VecDestroy(&x0));
    104:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Norm of 2nd column of X = %.3f\n",(double)nrm));
    105:   if (verbose) {
    106:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"After vectors - - - - - - - - -\n"));
    107:     PetscCall(DSView(ds,viewer));
    108:   }

    110:   PetscCall(PetscFree2(wr,wi));
    111:   PetscCall(DSDestroy(&ds));
    112:   PetscCall(SlepcFinalize());
    113:   return 0;
    114: }

    116: /*TEST

    118:    test:
    119:       suffix: 1
    120:       args: -n 7
    121:       requires: !complex
    122:       filter: sed -e 's/-0.00000/0.00000/'

    124:    test:
    125:       suffix: 1_complex
    126:       args: -n 7
    127:       requires: complex
    128:       filter: sed -e 's/-0.00000/0.00000/'

    130: TEST*/