Actual source code: test13.c

slepc-3.17.0 2022-03-31
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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;

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

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

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

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

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

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

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

 86: /*TEST

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

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

 97: TEST*/