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 DSHEP with block size larger than one.\n\n";

 13: #include <slepcds.h>

 15: int main(int argc,char **argv)
 16: {
 17:   DS             ds;
 18:   SlepcSC        sc;
 19:   PetscScalar    *A,*eig;
 20:   PetscInt       i,j,n,ld,bs,maxbw=3,nblks=8;
 21:   PetscViewer    viewer;
 22:   PetscBool      verbose;

 24:   PetscFunctionBeginUser;
 25:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
 26:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-maxbw",&maxbw,NULL));
 27:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-nblks",&nblks,NULL));
 28:   n = maxbw*nblks;
 29:   bs = maxbw;
 30:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Solve a block HEP Dense System - dimension %" PetscInt_FMT " (bandwidth=%" PetscInt_FMT ", blocks=%" PetscInt_FMT ").\n",n,maxbw,nblks));
 31:   PetscCall(PetscOptionsHasName(NULL,NULL,"-verbose",&verbose));

 33:   /* Create DS object */
 34:   PetscCall(DSCreate(PETSC_COMM_WORLD,&ds));
 35:   PetscCall(DSSetType(ds,DSHEP));
 36:   PetscCall(DSSetMethod(ds,3));   /* Select block divide-and-conquer */
 37:   PetscCall(DSSetBlockSize(ds,bs));
 38:   PetscCall(DSSetFromOptions(ds));
 39:   ld = n;
 40:   PetscCall(DSAllocate(ds,ld));
 41:   PetscCall(DSSetDimensions(ds,n,0,0));

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

 50:   /* Fill with a symmetric band Toeplitz matrix */
 51:   PetscCall(DSGetArray(ds,DS_MAT_A,&A));
 52:   for (i=0;i<n;i++) A[i+i*ld]=2.0;
 53:   for (j=1;j<=bs;j++) {
 54:     for (i=0;i<n-j;i++) { A[i+(i+j)*ld]=1.0; A[(i+j)+i*ld]=1.0; }
 55:   }
 56:   PetscCall(DSRestoreArray(ds,DS_MAT_A,&A));
 57:   PetscCall(DSSetState(ds,DS_STATE_RAW));
 58:   if (verbose) {
 59:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n"));
 60:     PetscCall(DSView(ds,viewer));
 61:   }

 63:   /* Solve */
 64:   PetscCall(PetscMalloc1(n,&eig));
 65:   PetscCall(DSGetSlepcSC(ds,&sc));
 66:   sc->comparison    = SlepcCompareSmallestReal;
 67:   sc->comparisonctx = NULL;
 68:   sc->map           = NULL;
 69:   sc->mapobj        = NULL;
 70:   PetscCall(DSSolve(ds,eig,NULL));
 71:   PetscCall(DSSort(ds,eig,NULL,NULL,NULL,NULL));
 72:   if (verbose) {
 73:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n"));
 74:     PetscCall(DSView(ds,viewer));
 75:   }

 77:   /* Print eigenvalues */
 78:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Computed eigenvalues =\n"));
 79:   for (i=0;i<n;i++) PetscCall(PetscViewerASCIIPrintf(viewer,"  %.5f\n",(double)PetscRealPart(eig[i])));

 81:   PetscCall(PetscFree(eig));
 82:   PetscCall(DSDestroy(&ds));
 83:   PetscCall(SlepcFinalize());
 84:   return 0;
 85: }

 87: /*TEST

 89:    test:
 90:       suffix: 1
 91:       requires: !complex !single

 93:    test:
 94:       suffix: 2
 95:       args: -nblks 1
 96:       requires: !complex

 98: TEST*/