Beispiel #1
0
	bool CinderDSAPI::init()
	{
		if (mDSAPI == nullptr)
			mDSAPI = DSAPIRef(DSCreate(DS_DS4_PLATFORM), DSDestroy);

		return open();
	}
Beispiel #2
0
int main(int argc,char **argv)
{
  PetscErrorCode ierr;
  DS             ds;
  PetscScalar    *A;
  PetscInt       i,j,n=10,ld;
  PetscViewer    viewer;
  PetscBool      verbose;

  SlepcInitialize(&argc,&argv,(char*)0,help);
  ierr = PetscOptionsGetInt(NULL,"-n",&n,NULL);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Compute symmetric matrix exponential - dimension %D.\n",n);CHKERRQ(ierr);
  ierr = PetscOptionsHasName(NULL,"-verbose",&verbose);CHKERRQ(ierr);

  /* Create DS object */
  ierr = DSCreate(PETSC_COMM_WORLD,&ds);CHKERRQ(ierr);
  ierr = DSSetType(ds,DSHEP);CHKERRQ(ierr);
  ierr = DSSetFromOptions(ds);CHKERRQ(ierr);
  ld = n+2;  /* test leading dimension larger than n */
  ierr = DSAllocate(ds,ld);CHKERRQ(ierr);
  ierr = DSSetDimensions(ds,n,0,0,0);CHKERRQ(ierr);

  /* Set up viewer */
  ierr = PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);CHKERRQ(ierr);
  ierr = PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL);CHKERRQ(ierr);
  ierr = DSView(ds,viewer);CHKERRQ(ierr);
  ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);CHKERRQ(ierr);
  }

  /* Fill with a symmetric Toeplitz matrix */
  ierr = DSGetArray(ds,DS_MAT_A,&A);CHKERRQ(ierr);
  for (i=0;i<n;i++) A[i+i*ld]=2.0;
  for (j=1;j<3;j++) {
    for (i=0;i<n-j;i++) { A[i+(i+j)*ld]=1.0; A[(i+j)+i*ld]=1.0; }
  }
  ierr = DSRestoreArray(ds,DS_MAT_A,&A);CHKERRQ(ierr);
  ierr = DSSetState(ds,DS_STATE_RAW);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"Matrix A - - - - - - - -\n");CHKERRQ(ierr);
    ierr = DSView(ds,viewer);CHKERRQ(ierr);
  }

  /* Compute matrix exponential */
  ierr = DSComputeFunction(ds,SLEPC_FUNCTION_EXP);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"Computed f(A) - - - - - - -\n");CHKERRQ(ierr);
    ierr = DSViewMat(ds,viewer,DS_MAT_F);CHKERRQ(ierr);
  }

  ierr = DSDestroy(&ds);CHKERRQ(ierr);
  ierr = SlepcFinalize();
  return 0;
}
Beispiel #3
0
/*@C
   EPSGetDS - Obtain the direct solver object associated to the eigensolver object.

   Not Collective

   Input Parameters:
.  eps - eigensolver context obtained from EPSCreate()

   Output Parameter:
.  ds - direct solver context

   Level: advanced

.seealso: EPSSetDS()
@*/
PetscErrorCode EPSGetDS(EPS eps,DS *ds)
{
    PetscErrorCode ierr;

    PetscFunctionBegin;
    PetscValidHeaderSpecific(eps,EPS_CLASSID,1);
    PetscValidPointer(ds,2);
    if (!eps->ds) {
        ierr = DSCreate(PetscObjectComm((PetscObject)eps),&eps->ds);
        CHKERRQ(ierr);
        ierr = PetscLogObjectParent((PetscObject)eps,(PetscObject)eps->ds);
        CHKERRQ(ierr);
    }
    *ds = eps->ds;
    PetscFunctionReturn(0);
}
Beispiel #4
0
	bool CinderDSAPI::init(uint32_t pSerialNo)
	{
		if (mDSAPI == nullptr)
			mDSAPI = DSAPIRef(DSCreate(DS_DS4_PLATFORM, pSerialNo), DSDestroy);

		if (mDSAPI)
		{
			if (!mHasValidConfig)
				mHasValidConfig = mDSAPI->probeConfiguration();
			if (!mHasValidCalib)
				mHasValidCalib = mDSAPI->isCalibrationValid();

			mIsInit = mHasValidConfig&&mHasValidCalib;
		}
		return mIsInit;
	}
Beispiel #5
0
int main(int argc,char **argv)
{
  PetscErrorCode ierr;
  DS             ds;
  SlepcSC        sc;
  PetscScalar    *A,*B,*wr,*wi;
  PetscReal      re,im;
  PetscInt       i,j,n=10,ld;
  PetscViewer    viewer;
  PetscBool      verbose;

  SlepcInitialize(&argc,&argv,(char*)0,help);
  ierr = PetscOptionsGetInt(NULL,"-n",&n,NULL);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Solve a Dense System of type GNHEP - dimension %D.\n",n);CHKERRQ(ierr);
  ierr = PetscOptionsHasName(NULL,"-verbose",&verbose);CHKERRQ(ierr);

  /* Create DS object */
  ierr = DSCreate(PETSC_COMM_WORLD,&ds);CHKERRQ(ierr);
  ierr = DSSetType(ds,DSGNHEP);CHKERRQ(ierr);
  ierr = DSSetFromOptions(ds);CHKERRQ(ierr);
  ld = n+2;  /* test leading dimension larger than n */
  ierr = DSAllocate(ds,ld);CHKERRQ(ierr);
  ierr = DSSetDimensions(ds,n,0,0,0);CHKERRQ(ierr);

  /* Set up viewer */
  ierr = PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);CHKERRQ(ierr);
  ierr = PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL);CHKERRQ(ierr);
  ierr = DSView(ds,viewer);CHKERRQ(ierr);
  ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);CHKERRQ(ierr);
  }

  /* Fill A with Grcar matrix */
  ierr = DSGetArray(ds,DS_MAT_A,&A);CHKERRQ(ierr);
  ierr = PetscMemzero(A,sizeof(PetscScalar)*ld*n);CHKERRQ(ierr);
  for (i=1;i<n;i++) A[i+(i-1)*ld]=-1.0;
  for (j=0;j<4;j++) {
    for (i=0;i<n-j;i++) A[i+(i+j)*ld]=1.0;
  }
  ierr = DSRestoreArray(ds,DS_MAT_A,&A);CHKERRQ(ierr);
  /* Fill B with an identity matrix */
  ierr = DSGetArray(ds,DS_MAT_B,&B);CHKERRQ(ierr);
  ierr = PetscMemzero(B,sizeof(PetscScalar)*ld*n);CHKERRQ(ierr);
  for (i=0;i<n;i++) B[i+i*ld]=1.0;
  ierr = DSRestoreArray(ds,DS_MAT_B,&B);CHKERRQ(ierr);

  if (verbose) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");CHKERRQ(ierr);
    ierr = DSView(ds,viewer);CHKERRQ(ierr);
  }

  /* Solve */
  ierr = PetscMalloc2(n,&wr,n,&wi);CHKERRQ(ierr);
  ierr = DSGetSlepcSC(ds,&sc);CHKERRQ(ierr);
  sc->comparison    = SlepcCompareLargestMagnitude;
  sc->comparisonctx = NULL;
  sc->map           = NULL;
  sc->mapobj        = NULL;
  ierr = DSSolve(ds,wr,wi);CHKERRQ(ierr);
  ierr = DSSort(ds,wr,wi,NULL,NULL,NULL);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n");CHKERRQ(ierr);
    ierr = DSView(ds,viewer);CHKERRQ(ierr);
  }

  /* Print eigenvalues */
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Computed eigenvalues =\n",n);CHKERRQ(ierr);
  for (i=0;i<n;i++) {
#if defined(PETSC_USE_COMPLEX)
    re = PetscRealPart(wr[i]);
    im = PetscImaginaryPart(wr[i]);
#else
    re = wr[i];
    im = wi[i];
#endif
    if (PetscAbs(im)<1e-10) {
      ierr = PetscViewerASCIIPrintf(viewer,"  %.5f\n",(double)re);CHKERRQ(ierr);
    } else {
      ierr = PetscViewerASCIIPrintf(viewer,"  %.5f%+.5fi\n",(double)re,(double)im);CHKERRQ(ierr);
    }
  }

  ierr = PetscFree2(wr,wi);CHKERRQ(ierr);
  ierr = DSDestroy(&ds);CHKERRQ(ierr);
  ierr = SlepcFinalize();
  return 0;
}
Beispiel #6
0
int main(int argc,char **argv)
{
  PetscErrorCode ierr;
  DS             ds;
  FN             f1,f2,f3,funs[3];
  PetscScalar    *Id,*A,*B,*wr,*wi,coeffs[2];
  PetscReal      tau=0.001,h,a=20,xi,re,im;
  PetscInt       i,n=10,ld,nev;
  PetscViewer    viewer;
  PetscBool      verbose;

  SlepcInitialize(&argc,&argv,(char*)0,help);
  ierr = PetscOptionsGetInt(NULL,"-n",&n,NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetReal(NULL,"-tau",&tau,NULL);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Solve a Dense System of type NEP - dimension %D, tau=%g.\n",n,(double)tau);CHKERRQ(ierr);
  ierr = PetscOptionsHasName(NULL,"-verbose",&verbose);CHKERRQ(ierr);

  /* Create DS object */
  ierr = DSCreate(PETSC_COMM_WORLD,&ds);CHKERRQ(ierr);
  ierr = DSSetType(ds,DSNEP);CHKERRQ(ierr);
  ierr = DSSetFromOptions(ds);CHKERRQ(ierr);

  /* Set functions (prior to DSAllocate) */
  ierr = FNCreate(PETSC_COMM_WORLD,&f1);CHKERRQ(ierr);
  ierr = FNSetType(f1,FNRATIONAL);CHKERRQ(ierr);
  coeffs[0] = -1.0; coeffs[1] = 0.0;
  ierr = FNSetParameters(f1,2,coeffs,0,NULL);CHKERRQ(ierr);

  ierr = FNCreate(PETSC_COMM_WORLD,&f2);CHKERRQ(ierr);
  ierr = FNSetType(f2,FNRATIONAL);CHKERRQ(ierr);
  coeffs[0] = 1.0;
  ierr = FNSetParameters(f2,1,coeffs,0,NULL);CHKERRQ(ierr);

  ierr = FNCreate(PETSC_COMM_WORLD,&f3);CHKERRQ(ierr);
  ierr = FNSetType(f3,FNEXP);CHKERRQ(ierr);
  coeffs[0] = -tau;
  ierr = FNSetParameters(f3,1,coeffs,0,NULL);CHKERRQ(ierr);

  funs[0] = f1;
  funs[1] = f2;
  funs[2] = f3;
  ierr = DSSetFN(ds,3,funs);CHKERRQ(ierr);

  /* Set dimensions */
  ld = n+2;  /* test leading dimension larger than n */
  ierr = DSAllocate(ds,ld);CHKERRQ(ierr);
  ierr = DSSetDimensions(ds,n,0,0,0);CHKERRQ(ierr);

  /* Set up viewer */
  ierr = PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);CHKERRQ(ierr);
  ierr = PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL);CHKERRQ(ierr);
  ierr = DSView(ds,viewer);CHKERRQ(ierr);
  ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);CHKERRQ(ierr);
  }

  /* Fill matrices */
  ierr = DSGetArray(ds,DS_MAT_E0,&Id);CHKERRQ(ierr);
  for (i=0;i<n;i++) Id[i+i*ld]=1.0;
  ierr = DSRestoreArray(ds,DS_MAT_E0,&Id);CHKERRQ(ierr);
  h = PETSC_PI/(PetscReal)(n+1);
  ierr = DSGetArray(ds,DS_MAT_E1,&A);CHKERRQ(ierr);
  for (i=0;i<n;i++) A[i+i*ld]=-2.0/(h*h)+a;
  for (i=1;i<n;i++) {
    A[i+(i-1)*ld]=1.0/(h*h);
    A[(i-1)+i*ld]=1.0/(h*h);
  }
  ierr = DSRestoreArray(ds,DS_MAT_E1,&A);CHKERRQ(ierr);
  ierr = DSGetArray(ds,DS_MAT_E2,&B);CHKERRQ(ierr);
  for (i=0;i<n;i++) {
    xi = (i+1)*h;
    B[i+i*ld] = -4.1+xi*(1.0-PetscExpReal(xi-PETSC_PI));
  }
  ierr = DSRestoreArray(ds,DS_MAT_E2,&B);CHKERRQ(ierr);

  if (verbose) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");CHKERRQ(ierr);
    ierr = DSView(ds,viewer);CHKERRQ(ierr);
  }

  /* Solve */
  ierr = PetscMalloc2(n,&wr,n,&wi);CHKERRQ(ierr);
  ierr = DSSolve(ds,wr,wi);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n");CHKERRQ(ierr);
    ierr = DSView(ds,viewer);CHKERRQ(ierr);
  }

  /* Print first eigenvalue */
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Computed eigenvalue =\n",n);CHKERRQ(ierr);
  nev = 1;
  for (i=0;i<nev;i++) {
#if defined(PETSC_USE_COMPLEX)
    re = PetscRealPart(wr[i]);
    im = PetscImaginaryPart(wr[i]);
#else
    re = wr[i];
    im = wi[i];
#endif
    if (PetscAbs(im)<1e-10) {
      ierr = PetscViewerASCIIPrintf(viewer,"  %.5f\n",(double)re);CHKERRQ(ierr);
    } else {
      ierr = PetscViewerASCIIPrintf(viewer,"  %.5f%+.5fi\n",(double)re,(double)im);CHKERRQ(ierr);
    }
  }

  ierr = PetscFree2(wr,wi);CHKERRQ(ierr);
  ierr = FNDestroy(&f1);CHKERRQ(ierr);
  ierr = FNDestroy(&f2);CHKERRQ(ierr);
  ierr = FNDestroy(&f3);CHKERRQ(ierr);
  ierr = DSDestroy(&ds);CHKERRQ(ierr);
  ierr = SlepcFinalize();
  return 0;
}
Beispiel #7
0
int main(int argc,char **argv)
{
  PetscErrorCode ierr;
  DS             ds;
  SlepcSC        sc;
  PetscReal      *T,*s,re,im;
  PetscScalar    *eigr,*eigi;
  PetscInt       i,n=10,l=2,k=5,ld;
  PetscViewer    viewer;
  PetscBool      verbose;

  SlepcInitialize(&argc,&argv,(char*)0,help);
  ierr = PetscOptionsGetInt(NULL,"-n",&n,NULL);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Solve a Dense System of type GHIEP with compact storage - dimension %D.\n",n);CHKERRQ(ierr);
  ierr = PetscOptionsGetInt(NULL,"-l",&l,NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetInt(NULL,"-k",&k,NULL);CHKERRQ(ierr);
  if (l>n || k>n || l>k) SETERRQ(PETSC_COMM_WORLD,1,"Wrong value of dimensions");
  ierr = PetscOptionsHasName(NULL,"-verbose",&verbose);CHKERRQ(ierr);

  /* Create DS object */
  ierr = DSCreate(PETSC_COMM_WORLD,&ds);CHKERRQ(ierr);
  ierr = DSSetType(ds,DSGHIEP);CHKERRQ(ierr);
  ierr = DSSetFromOptions(ds);CHKERRQ(ierr);
  ld = n+2;  /* test leading dimension larger than n */
  ierr = DSAllocate(ds,ld);CHKERRQ(ierr);
  ierr = DSSetDimensions(ds,n,0,l,k);CHKERRQ(ierr);
  ierr = DSSetCompact(ds,PETSC_TRUE);CHKERRQ(ierr);

  /* Set up viewer */
  ierr = PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);CHKERRQ(ierr);
  ierr = PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL);CHKERRQ(ierr);
  ierr = DSView(ds,viewer);CHKERRQ(ierr);
  ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);CHKERRQ(ierr);
  }

  /* Fill arrow-tridiagonal matrix */
  ierr = DSGetArrayReal(ds,DS_MAT_T,&T);CHKERRQ(ierr);
  ierr = DSGetArrayReal(ds,DS_MAT_D,&s);CHKERRQ(ierr);
  for (i=0;i<n;i++) T[i] = (PetscReal)(i+1);
  for (i=k;i<n-1;i++) T[i+ld] = 1.0;
  for (i=l;i<k;i++) T[i+2*ld] = 1.0;
  T[2*ld+l+1] = -7; T[ld+k+1] = -7;
  /* Signature matrix */
  for (i=0;i<n;i++) s[i] = 1.0;
  s[l+1] = -1.0;
  s[k+1] = -1.0;
  ierr = DSRestoreArrayReal(ds,DS_MAT_T,&T);CHKERRQ(ierr);
  ierr = DSRestoreArrayReal(ds,DS_MAT_D,&s);CHKERRQ(ierr);
  if (l==0 && k==0) {
    ierr = DSSetState(ds,DS_STATE_INTERMEDIATE);CHKERRQ(ierr);
  } else {
    ierr = DSSetState(ds,DS_STATE_RAW);CHKERRQ(ierr);
  }
  if (verbose) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");CHKERRQ(ierr);
    ierr = DSView(ds,viewer);CHKERRQ(ierr);
  }

  /* Solve */
  ierr = PetscCalloc2(n,&eigr,n,&eigi);CHKERRQ(ierr);
  ierr = DSGetSlepcSC(ds,&sc);CHKERRQ(ierr);
  sc->comparison    = SlepcCompareLargestMagnitude;
  sc->comparisonctx = NULL;
  sc->map           = NULL;
  sc->mapobj        = NULL;
  ierr = DSSolve(ds,eigr,eigi);CHKERRQ(ierr);
  ierr = DSSort(ds,eigr,eigi,NULL,NULL,NULL);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n");CHKERRQ(ierr);
    ierr = DSView(ds,viewer);CHKERRQ(ierr);
  }

  /* Print eigenvalues */
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Computed eigenvalues =\n",n);CHKERRQ(ierr);
  for (i=0;i<n;i++) {
#if defined(PETSC_USE_COMPLEX)
    re = PetscRealPart(eigr[i]);
    im = PetscImaginaryPart(eigr[i]);
#else
    re = eigr[i];
    im = eigi[i];
#endif
    if (PetscAbs(im)<1e-10) {
      ierr = PetscViewerASCIIPrintf(viewer,"  %.5f\n",(double)re);CHKERRQ(ierr);
    } else {
      ierr = PetscViewerASCIIPrintf(viewer,"  %.5f%+.5fi\n",(double)re,(double)im);CHKERRQ(ierr);
    }
  }
  ierr = PetscFree2(eigr,eigi);CHKERRQ(ierr);
  ierr = DSDestroy(&ds);CHKERRQ(ierr);
  ierr = SlepcFinalize();
  return 0;
}
Beispiel #8
0
int main(int argc,char **argv)
{
  PetscErrorCode ierr;
  DS             ds;
  SlepcSC        sc;
  PetscScalar    *A,*eig;
  PetscInt       i,j,n,ld,bs,maxbw=3,nblks=8;
  PetscViewer    viewer;
  PetscBool      verbose;

  SlepcInitialize(&argc,&argv,(char*)0,help);
  ierr = PetscOptionsGetInt(NULL,"-maxbw",&maxbw,NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetInt(NULL,"-nblks",&nblks,NULL);CHKERRQ(ierr);
  n = maxbw*nblks;
  bs = maxbw;
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Solve a block HEP Dense System - dimension %D (bandwidth=%D, blocks=%D).\n",n,maxbw,nblks);CHKERRQ(ierr);
  ierr = PetscOptionsHasName(NULL,"-verbose",&verbose);CHKERRQ(ierr);

  /* Create DS object */
  ierr = DSCreate(PETSC_COMM_WORLD,&ds);CHKERRQ(ierr);
  ierr = DSSetType(ds,DSHEP);CHKERRQ(ierr);
  ierr = DSSetMethod(ds,3);CHKERRQ(ierr);   /* Select block divide-and-conquer */
  ierr = DSSetBlockSize(ds,bs);CHKERRQ(ierr);
  ierr = DSSetFromOptions(ds);CHKERRQ(ierr);
  ld = n;
  ierr = DSAllocate(ds,ld);CHKERRQ(ierr);
  ierr = DSSetDimensions(ds,n,0,0,0);CHKERRQ(ierr);

  /* Set up viewer */
  ierr = PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);CHKERRQ(ierr);
  ierr = PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL);CHKERRQ(ierr);
  ierr = DSView(ds,viewer);CHKERRQ(ierr);
  ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);CHKERRQ(ierr);
  }

  /* Fill with a symmetric band Toeplitz matrix */
  ierr = DSGetArray(ds,DS_MAT_A,&A);CHKERRQ(ierr);
  for (i=0;i<n;i++) A[i+i*ld]=2.0;
  for (j=1;j<=bs;j++) {
    for (i=0;i<n-j;i++) { A[i+(i+j)*ld]=1.0; A[(i+j)+i*ld]=1.0; }
  }
  ierr = DSRestoreArray(ds,DS_MAT_A,&A);CHKERRQ(ierr);
  ierr = DSSetState(ds,DS_STATE_RAW);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");CHKERRQ(ierr);
    ierr = DSView(ds,viewer);CHKERRQ(ierr);
  }

  /* Solve */
  ierr = PetscMalloc1(n,&eig);CHKERRQ(ierr);
  ierr = DSGetSlepcSC(ds,&sc);CHKERRQ(ierr);
  sc->comparison    = SlepcCompareSmallestReal;
  sc->comparisonctx = NULL;
  sc->map           = NULL;
  sc->mapobj        = NULL;
  ierr = DSSolve(ds,eig,NULL);CHKERRQ(ierr);
  ierr = DSSort(ds,eig,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n");CHKERRQ(ierr);
    ierr = DSView(ds,viewer);CHKERRQ(ierr);
  }

  /* Print eigenvalues */
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Computed eigenvalues =\n",n);CHKERRQ(ierr);
  for (i=0;i<n;i++) {
    ierr = PetscViewerASCIIPrintf(viewer,"  %.5f\n",(double)PetscRealPart(eig[i]));CHKERRQ(ierr);
  }

  ierr = PetscFree(eig);CHKERRQ(ierr);
  ierr = DSDestroy(&ds);CHKERRQ(ierr);
  ierr = SlepcFinalize();
  return 0;
}