Actual source code: test13.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[] = "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;

 25:   SlepcInitialize(&argc,&argv,(char*)0,help);
 26:   PetscOptionsGetInt(NULL,NULL,"-maxbw",&maxbw,NULL);
 27:   PetscOptionsGetInt(NULL,NULL,"-nblks",&nblks,NULL);
 28:   n = maxbw*nblks;
 29:   bs = maxbw;
 30:   PetscPrintf(PETSC_COMM_WORLD,"Solve a block HEP Dense System - dimension %" PetscInt_FMT " (bandwidth=%" PetscInt_FMT ", blocks=%" PetscInt_FMT ").\n",n,maxbw,nblks);
 31:   PetscOptionsHasName(NULL,NULL,"-verbose",&verbose);

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

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

 50:   /* Fill with a symmetric band Toeplitz matrix */
 51:   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:   DSRestoreArray(ds,DS_MAT_A,&A);
 57:   DSSetState(ds,DS_STATE_RAW);
 58:   if (verbose) {
 59:     PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");
 60:     DSView(ds,viewer);
 61:   }

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

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

 81:   PetscFree(eig);
 82:   DSDestroy(&ds);
 83:   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*/