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static char help[] = "Solves a problem associated to the Brusselator wave model in chemical reactions, illustrating the use of shell matrices.\n\n"
static char help[] = "Solves a problem associated to the Brusselator wave model in chemical reactions, illustrating the use of shell matrices.\n\n"
  "The command line options are:\n"
  "The command line options are:\n"
  "  -n <n>, where <n> = block dimension of the 2x2 block matrix.\n"
  "  -n <n>, where <n> = block dimension of the 2x2 block matrix.\n"
  "  -L <L>, where <L> = bifurcation parameter.\n"
  "  -L <L>, where <L> = bifurcation parameter.\n"
  "  -alpha <alpha>, -beta <beta>, -delta1 <delta1>,  -delta2 <delta2>,\n"
  "  -alpha <alpha>, -beta <beta>, -delta1 <delta1>,  -delta2 <delta2>,\n"
  "       where <alpha> <beta> <delta1> <delta2> = model parameters.\n\n";
  "       where <alpha> <beta> <delta1> <delta2> = model parameters.\n\n";
 
 
#include "slepceps.h"
#include "slepceps.h"
 
 
/*
/*
   This example computes the eigenvalues with largest real part of the
   This example computes the eigenvalues with largest real part of the
   following matrix
   following matrix
 
 
        A = [ tau1*T+(beta-1)*I     alpha^2*I
        A = [ tau1*T+(beta-1)*I     alpha^2*I
                  -beta*I        tau2*T-alpha^2*I ],
                  -beta*I        tau2*T-alpha^2*I ],
 
 
   where
   where
 
 
        T = tridiag{1,-2,1}
        T = tridiag{1,-2,1}
        h = 1/(n+1)
        h = 1/(n+1)
        tau1 = delta1/(h*L)^2
        tau1 = delta1/(h*L)^2
        tau2 = delta2/(h*L)^2
        tau2 = delta2/(h*L)^2
 */
 */
 
 
 
 
/*
/*
   Matrix operations
   Matrix operations
*/
*/
PetscErrorCode MatBrussel_Mult(Mat,Vec,Vec);
PetscErrorCode MatBrussel_Mult(Mat,Vec,Vec);
PetscErrorCode MatBrussel_Shift(PetscScalar*,Mat);
PetscErrorCode MatBrussel_Shift(PetscScalar*,Mat);
PetscErrorCode MatBrussel_GetDiagonal(Mat,Vec);
PetscErrorCode MatBrussel_GetDiagonal(Mat,Vec);
 
 
typedef struct {
typedef struct {
  Mat         T;
  Mat         T;
  Vec         x1, x2, y1, y2;
  Vec         x1, x2, y1, y2;
  PetscScalar alpha, beta, tau1, tau2, sigma;
  PetscScalar alpha, beta, tau1, tau2, sigma;
} CTX_BRUSSEL;
} CTX_BRUSSEL;
 
 
#undef __FUNCT__
#undef __FUNCT__
#define __FUNCT__ "main"
#define __FUNCT__ "main"
int main( int argc, char **argv )
int main( int argc, char **argv )
{
{
  Mat            A;               /* eigenvalue problem matrix */
  Mat            A;               /* eigenvalue problem matrix */
  EPS            eps;             /* eigenproblem solver context */
  EPS            eps;             /* eigenproblem solver context */
  EPSType        type;
  EPSType        type;
  PetscReal      error, tol, re, im;
  PetscReal      error, tol, re, im;
  PetscScalar    delta1, delta2, L, h, kr, ki, value[3];
  PetscScalar    delta1, delta2, L, h, kr, ki, value[3];
  PetscInt       N=30, n, i, col[3], Istart, Iend;
  PetscInt       N=30, n, i, col[3], Istart, Iend;
  int            nev, maxit, its, nconv;
  int            nev, maxit, its, nconv;
  PetscTruth     FirstBlock=PETSC_FALSE, LastBlock=PETSC_FALSE;
  PetscTruth     FirstBlock=PETSC_FALSE, LastBlock=PETSC_FALSE;
  PetscErrorCode ierr;
  PetscErrorCode ierr;
  CTX_BRUSSEL    *ctx;
  CTX_BRUSSEL    *ctx;
 
 
  SlepcInitialize(&argc,&argv,(char*)0,help);
  SlepcInitialize(&argc,&argv,(char*)0,help);
 
 
  ierr = PetscOptionsGetInt(PETSC_NULL,"-n",&N,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetInt(PETSC_NULL,"-n",&N,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD,"\nBrusselator wave model, n=%d\n\n",N);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD,"\nBrusselator wave model, n=%d\n\n",N);CHKERRQ(ierr);
 
 
  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
        Generate the matrix
        Generate the matrix
     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 
 
  /*
  /*
     Create shell matrix context and set default parameters
     Create shell matrix context and set default parameters
  */
  */
  ierr = PetscNew(CTX_BRUSSEL,&ctx);CHKERRQ(ierr);
  ierr = PetscNew(CTX_BRUSSEL,&ctx);CHKERRQ(ierr);
  ctx->alpha = 2.0;
  ctx->alpha = 2.0;
  ctx->beta  = 5.45;
  ctx->beta  = 5.45;
  delta1     = 0.008;
  delta1     = 0.008;
  delta2     = 0.004;
  delta2     = 0.004;
  L          = 0.51302;
  L          = 0.51302;
 
 
  /*
  /*
     Look the command line for user-provided parameters
     Look the command line for user-provided parameters
  */
  */
  ierr = PetscOptionsGetScalar(PETSC_NULL,"-L",&L,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetScalar(PETSC_NULL,"-L",&L,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetScalar(PETSC_NULL,"-alpha",&ctx->alpha,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetScalar(PETSC_NULL,"-alpha",&ctx->alpha,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetScalar(PETSC_NULL,"-beta",&ctx->beta,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetScalar(PETSC_NULL,"-beta",&ctx->beta,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetScalar(PETSC_NULL,"-delta1",&delta1,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetScalar(PETSC_NULL,"-delta1",&delta1,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetScalar(PETSC_NULL,"-delta2",&delta2,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetScalar(PETSC_NULL,"-delta2",&delta2,PETSC_NULL);CHKERRQ(ierr);
 
 
  /*
  /*
     Create matrix T
     Create matrix T
  */
  */
  ierr = MatCreate(PETSC_COMM_WORLD,&ctx->T);CHKERRQ(ierr);
  ierr = MatCreate(PETSC_COMM_WORLD,&ctx->T);CHKERRQ(ierr);
  ierr = MatSetSizes(ctx->T,PETSC_DECIDE,PETSC_DECIDE,N,N);CHKERRQ(ierr);
  ierr = MatSetSizes(ctx->T,PETSC_DECIDE,PETSC_DECIDE,N,N);CHKERRQ(ierr);
  ierr = MatSetFromOptions(ctx->T);CHKERRQ(ierr);
  ierr = MatSetFromOptions(ctx->T);CHKERRQ(ierr);
 
 
  ierr = MatGetOwnershipRange(ctx->T,&Istart,&Iend);CHKERRQ(ierr);
  ierr = MatGetOwnershipRange(ctx->T,&Istart,&Iend);CHKERRQ(ierr);
  if (Istart==0) FirstBlock=PETSC_TRUE;
  if (Istart==0) FirstBlock=PETSC_TRUE;
  if (Iend==N) LastBlock=PETSC_TRUE;
  if (Iend==N) LastBlock=PETSC_TRUE;
  value[0]=1.0; value[1]=-2.0; value[2]=1.0;
  value[0]=1.0; value[1]=-2.0; value[2]=1.0;
  for( i=(FirstBlock? Istart+1: Istart); i<(LastBlock? Iend-1: Iend); i++ ) {
  for( i=(FirstBlock? Istart+1: Istart); i<(LastBlock? Iend-1: Iend); i++ ) {
    col[0]=i-1; col[1]=i; col[2]=i+1;
    col[0]=i-1; col[1]=i; col[2]=i+1;
    ierr = MatSetValues(ctx->T,1,&i,3,col,value,INSERT_VALUES);CHKERRQ(ierr);
    ierr = MatSetValues(ctx->T,1,&i,3,col,value,INSERT_VALUES);CHKERRQ(ierr);
  }
  }
  if (LastBlock) {
  if (LastBlock) {
    i=N-1; col[0]=N-2; col[1]=N-1;
    i=N-1; col[0]=N-2; col[1]=N-1;
    ierr = MatSetValues(ctx->T,1,&i,2,col,value,INSERT_VALUES);CHKERRQ(ierr);
    ierr = MatSetValues(ctx->T,1,&i,2,col,value,INSERT_VALUES);CHKERRQ(ierr);
  }
  }
  if (FirstBlock) {
  if (FirstBlock) {
    i=0; col[0]=0; col[1]=1; value[0]=-2.0; value[1]=1.0;
    i=0; col[0]=0; col[1]=1; value[0]=-2.0; value[1]=1.0;
    ierr = MatSetValues(ctx->T,1,&i,2,col,value,INSERT_VALUES);CHKERRQ(ierr);
    ierr = MatSetValues(ctx->T,1,&i,2,col,value,INSERT_VALUES);CHKERRQ(ierr);
  }
  }
 
 
  ierr = MatAssemblyBegin(ctx->T,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
  ierr = MatAssemblyBegin(ctx->T,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
  ierr = MatAssemblyEnd(ctx->T,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
  ierr = MatAssemblyEnd(ctx->T,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
  ierr = MatGetLocalSize(ctx->T,&n,PETSC_NULL);CHKERRQ(ierr);
  ierr = MatGetLocalSize(ctx->T,&n,PETSC_NULL);CHKERRQ(ierr);
 
 
  /*
  /*
     Fill the remaining information in the shell matrix context
     Fill the remaining information in the shell matrix context
     and create auxiliary vectors
     and create auxiliary vectors
  */
  */
  h = 1.0 / (double)(N+1);
  h = 1.0 / (double)(N+1);
  ctx->tau1 = delta1 / ((h*L)*(h*L));
  ctx->tau1 = delta1 / ((h*L)*(h*L));
  ctx->tau2 = delta2 / ((h*L)*(h*L));
  ctx->tau2 = delta2 / ((h*L)*(h*L));
  ctx->sigma = 0.0;
  ctx->sigma = 0.0;
  ierr = VecCreateMPIWithArray(PETSC_COMM_WORLD,n,PETSC_DECIDE,PETSC_NULL,&ctx->x1);CHKERRQ(ierr);
  ierr = VecCreateMPIWithArray(PETSC_COMM_WORLD,n,PETSC_DECIDE,PETSC_NULL,&ctx->x1);CHKERRQ(ierr);
  ierr = VecCreateMPIWithArray(PETSC_COMM_WORLD,n,PETSC_DECIDE,PETSC_NULL,&ctx->x2);CHKERRQ(ierr);
  ierr = VecCreateMPIWithArray(PETSC_COMM_WORLD,n,PETSC_DECIDE,PETSC_NULL,&ctx->x2);CHKERRQ(ierr);
  ierr = VecCreateMPIWithArray(PETSC_COMM_WORLD,n,PETSC_DECIDE,PETSC_NULL,&ctx->y1);CHKERRQ(ierr);
  ierr = VecCreateMPIWithArray(PETSC_COMM_WORLD,n,PETSC_DECIDE,PETSC_NULL,&ctx->y1);CHKERRQ(ierr);
  ierr = VecCreateMPIWithArray(PETSC_COMM_WORLD,n,PETSC_DECIDE,PETSC_NULL,&ctx->y2);CHKERRQ(ierr);
  ierr = VecCreateMPIWithArray(PETSC_COMM_WORLD,n,PETSC_DECIDE,PETSC_NULL,&ctx->y2);CHKERRQ(ierr);
 
 
  /*
  /*
     Create the shell matrix
     Create the shell matrix
  */
  */
  ierr = MatCreateShell(PETSC_COMM_WORLD,2*n,2*n,2*N,2*N,(void*)ctx,&A);CHKERRQ(ierr);
  ierr = MatCreateShell(PETSC_COMM_WORLD,2*n,2*n,2*N,2*N,(void*)ctx,&A);CHKERRQ(ierr);
  ierr = MatShellSetOperation(A,MATOP_MULT,(void(*)())MatBrussel_Mult);CHKERRQ(ierr);
  ierr = MatShellSetOperation(A,MATOP_MULT,(void(*)())MatBrussel_Mult);CHKERRQ(ierr);
  ierr = MatShellSetOperation(A,MATOP_SHIFT,(void(*)())MatBrussel_Shift);CHKERRQ(ierr);
  ierr = MatShellSetOperation(A,MATOP_SHIFT,(void(*)())MatBrussel_Shift);CHKERRQ(ierr);
  ierr = MatShellSetOperation(A,MATOP_GET_DIAGONAL,(void(*)())MatBrussel_GetDiagonal);CHKERRQ(ierr);
  ierr = MatShellSetOperation(A,MATOP_GET_DIAGONAL,(void(*)())MatBrussel_GetDiagonal);CHKERRQ(ierr);
 
 
  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                Create the eigensolver and set various options
                Create the eigensolver and set various options
     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 
 
  /*
  /*
     Create eigensolver context
     Create eigensolver context
  */
  */
  ierr = EPSCreate(PETSC_COMM_WORLD,&eps);CHKERRQ(ierr);
  ierr = EPSCreate(PETSC_COMM_WORLD,&eps);CHKERRQ(ierr);
 
 
  /*
  /*
     Set operators. In this case, it is a standard eigenvalue problem
     Set operators. In this case, it is a standard eigenvalue problem
  */
  */
  ierr = EPSSetOperators(eps,A,PETSC_NULL);CHKERRQ(ierr);
  ierr = EPSSetOperators(eps,A,PETSC_NULL);CHKERRQ(ierr);
  ierr = EPSSetProblemType(eps,EPS_NHEP);CHKERRQ(ierr);
  ierr = EPSSetProblemType(eps,EPS_NHEP);CHKERRQ(ierr);
 
 
  /*
  /*
     Force to use ARPACK if it is installed and ask for the rightmost eigenvalues
     Force to use ARPACK if it is installed and ask for the rightmost eigenvalues
  */
  */
#if defined(SLEPC_HAVE_ARPACK)
#if defined(SLEPC_HAVE_ARPACK)
  ierr = EPSSetType(eps,EPSARPACK);CHKERRQ(ierr);
  ierr = EPSSetType(eps,EPSARPACK);CHKERRQ(ierr);
#else
#else
  ierr = EPSSetType(eps, EPSLAPACK);CHKERRQ(ierr);
  ierr = EPSSetType(eps, EPSLAPACK);CHKERRQ(ierr);
#endif
#endif
  ierr = EPSSetWhichEigenpairs(eps,EPS_LARGEST_REAL);CHKERRQ(ierr);
  ierr = EPSSetWhichEigenpairs(eps,EPS_LARGEST_REAL);CHKERRQ(ierr);
 
 
  /*
  /*
     Set other solver options at runtime
     Set other solver options at runtime
  */
  */
  ierr = EPSSetFromOptions(eps);CHKERRQ(ierr);
  ierr = EPSSetFromOptions(eps);CHKERRQ(ierr);
 
 
  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                      Solve the eigensystem
                      Solve the eigensystem
     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 
 
  ierr = EPSSolve(eps);CHKERRQ(ierr);
  ierr = EPSSolve(eps);CHKERRQ(ierr);
  ierr = EPSGetIterationNumber(eps, &its);CHKERRQ(ierr);
  ierr = EPSGetIterationNumber(eps, &its);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Number of iterations of the method: %d\n",its);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Number of iterations of the method: %d\n",its);CHKERRQ(ierr);
 
 
  /*
  /*
     Optional: Get some information from the solver and display it
     Optional: Get some information from the solver and display it
  */
  */
  ierr = EPSGetType(eps,&type);CHKERRQ(ierr);
  ierr = EPSGetType(eps,&type);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type);CHKERRQ(ierr);
  ierr = EPSGetDimensions(eps,&nev,PETSC_NULL);CHKERRQ(ierr);
  ierr = EPSGetDimensions(eps,&nev,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %d\n",nev);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %d\n",nev);CHKERRQ(ierr);
  ierr = EPSGetTolerances(eps,&tol,&maxit);CHKERRQ(ierr);
  ierr = EPSGetTolerances(eps,&tol,&maxit);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Stopping condition: tol=%.4g, maxit=%d\n",tol,maxit);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Stopping condition: tol=%.4g, maxit=%d\n",tol,maxit);CHKERRQ(ierr);
 
 
  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                    Display solution and clean up
                    Display solution and clean up
     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 
 
  /*
  /*
     Get number of converged eigenpairs
     Get number of converged eigenpairs
  */
  */
  ierr = EPSGetConverged(eps,&nconv);CHKERRQ(ierr);
  ierr = EPSGetConverged(eps,&nconv);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Number of converged approximate eigenpairs: %d\n\n",nconv);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Number of converged approximate eigenpairs: %d\n\n",nconv);CHKERRQ(ierr);
 
 
  if (nconv>0) {
  if (nconv>0) {
    /*
    /*
       Display eigenvalues and relative errors
       Display eigenvalues and relative errors
    */
    */
    ierr = PetscPrintf(PETSC_COMM_WORLD,
    ierr = PetscPrintf(PETSC_COMM_WORLD,
         "           k             ||Ax-kx||/||kx||\n"
         "           k             ||Ax-kx||/||kx||\n"
         "  --------------------- ------------------\n" );CHKERRQ(ierr);
         "  --------------------- ------------------\n" );CHKERRQ(ierr);
    for( i=0; i<nconv; i++ ) {
    for( i=0; i<nconv; i++ ) {
      /*
      /*
         Get converged eigenpairs: i-th eigenvalue is stored in kr (real part) and
         Get converged eigenpairs: i-th eigenvalue is stored in kr (real part) and
         ki (imaginary part)
         ki (imaginary part)
      */
      */
      ierr = EPSGetEigenpair(eps,i,&kr,&ki,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
      ierr = EPSGetEigenpair(eps,i,&kr,&ki,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
 
 
      /*
      /*
         Compute the relative error associated to each eigenpair
         Compute the relative error associated to each eigenpair
      */
      */
      ierr = EPSComputeRelativeError(eps,i,&error);CHKERRQ(ierr);
      ierr = EPSComputeRelativeError(eps,i,&error);CHKERRQ(ierr);
 
 
#if defined(PETSC_USE_COMPLEX)
#if defined(PETSC_USE_COMPLEX)
      re = PetscRealPart(kr);
      re = PetscRealPart(kr);
      im = PetscImaginaryPart(kr);
      im = PetscImaginaryPart(kr);
#else
#else
      re = kr;
      re = kr;
      im = ki;
      im = ki;
#endif
#endif
      if( im != 0.0 ) {
      if( im != 0.0 ) {
        ierr = PetscPrintf(PETSC_COMM_WORLD," % 6f %+6f i",re,im);CHKERRQ(ierr);
        ierr = PetscPrintf(PETSC_COMM_WORLD," % 6f %+6f i",re,im);CHKERRQ(ierr);
      } else {
      } else {
        ierr = PetscPrintf(PETSC_COMM_WORLD,"       % 6f      ",re); CHKERRQ(ierr);
        ierr = PetscPrintf(PETSC_COMM_WORLD,"       % 6f      ",re); CHKERRQ(ierr);
      }
      }
      ierr = PetscPrintf(PETSC_COMM_WORLD," % 12f\n",error);CHKERRQ(ierr);
      ierr = PetscPrintf(PETSC_COMM_WORLD," % 12g\n",error);CHKERRQ(ierr);
    }
    }
    ierr = PetscPrintf(PETSC_COMM_WORLD,"\n" );CHKERRQ(ierr);
    ierr = PetscPrintf(PETSC_COMM_WORLD,"\n" );CHKERRQ(ierr);
  }
  }
 
 
  /*
  /*
     Free work space
     Free work space
  */
  */
  ierr = EPSDestroy(eps);CHKERRQ(ierr);
  ierr = EPSDestroy(eps);CHKERRQ(ierr);
  ierr = MatDestroy(A);CHKERRQ(ierr);
  ierr = MatDestroy(A);CHKERRQ(ierr);
  ierr = MatDestroy(ctx->T);CHKERRQ(ierr);
  ierr = MatDestroy(ctx->T);CHKERRQ(ierr);
  ierr = VecDestroy(ctx->x1);CHKERRQ(ierr);
  ierr = VecDestroy(ctx->x1);CHKERRQ(ierr);
  ierr = VecDestroy(ctx->x2);CHKERRQ(ierr);
  ierr = VecDestroy(ctx->x2);CHKERRQ(ierr);
  ierr = VecDestroy(ctx->y1);CHKERRQ(ierr);
  ierr = VecDestroy(ctx->y1);CHKERRQ(ierr);
  ierr = VecDestroy(ctx->y2);CHKERRQ(ierr);
  ierr = VecDestroy(ctx->y2);CHKERRQ(ierr);
  ierr = PetscFree(ctx);CHKERRQ(ierr);
  ierr = PetscFree(ctx);CHKERRQ(ierr);
  ierr = SlepcFinalize();CHKERRQ(ierr);
  ierr = SlepcFinalize();CHKERRQ(ierr);
  return 0;
  return 0;
}
}
 
 
#undef __FUNCT__
#undef __FUNCT__
#define __FUNCT__ "MatBrussel_Mult"
#define __FUNCT__ "MatBrussel_Mult"
PetscErrorCode MatBrussel_Mult(Mat A,Vec x,Vec y)
PetscErrorCode MatBrussel_Mult(Mat A,Vec x,Vec y)
{
{
  PetscErrorCode ierr;
  PetscErrorCode ierr;
  PetscInt       n;
  PetscInt       n;
  PetscScalar    *px, *py;
  PetscScalar    *px, *py;
  CTX_BRUSSEL    *ctx;
  CTX_BRUSSEL    *ctx;
 
 
  PetscFunctionBegin;
  PetscFunctionBegin;
  ierr = MatShellGetContext(A,(void**)&ctx);CHKERRQ(ierr);
  ierr = MatShellGetContext(A,(void**)&ctx);CHKERRQ(ierr);
  ierr = MatGetLocalSize(ctx->T,&n,PETSC_NULL);CHKERRQ(ierr);
  ierr = MatGetLocalSize(ctx->T,&n,PETSC_NULL);CHKERRQ(ierr);
  ierr = VecGetArray(x,&px);CHKERRQ(ierr);
  ierr = VecGetArray(x,&px);CHKERRQ(ierr);
  ierr = VecGetArray(y,&py);CHKERRQ(ierr);
  ierr = VecGetArray(y,&py);CHKERRQ(ierr);
  ierr = VecPlaceArray(ctx->x1,px);CHKERRQ(ierr);
  ierr = VecPlaceArray(ctx->x1,px);CHKERRQ(ierr);
  ierr = VecPlaceArray(ctx->x2,px+n);CHKERRQ(ierr);
  ierr = VecPlaceArray(ctx->x2,px+n);CHKERRQ(ierr);
  ierr = VecPlaceArray(ctx->y1,py);CHKERRQ(ierr);
  ierr = VecPlaceArray(ctx->y1,py);CHKERRQ(ierr);
  ierr = VecPlaceArray(ctx->y2,py+n);CHKERRQ(ierr);
  ierr = VecPlaceArray(ctx->y2,py+n);CHKERRQ(ierr);
 
 
  ierr = MatMult(ctx->T,ctx->x1,ctx->y1);CHKERRQ(ierr);
  ierr = MatMult(ctx->T,ctx->x1,ctx->y1);CHKERRQ(ierr);
  ierr = VecScale(ctx->y1,ctx->tau1);CHKERRQ(ierr);
  ierr = VecScale(ctx->y1,ctx->tau1);CHKERRQ(ierr);
  ierr = VecAXPY(ctx->y1,ctx->beta - 1.0 + ctx->sigma,ctx->x1);CHKERRQ(ierr);
  ierr = VecAXPY(ctx->y1,ctx->beta - 1.0 + ctx->sigma,ctx->x1);CHKERRQ(ierr);
  ierr = VecAXPY(ctx->y1,ctx->alpha * ctx->alpha,ctx->x2);CHKERRQ(ierr);
  ierr = VecAXPY(ctx->y1,ctx->alpha * ctx->alpha,ctx->x2);CHKERRQ(ierr);
 
 
  ierr = MatMult(ctx->T,ctx->x2,ctx->y2);CHKERRQ(ierr);
  ierr = MatMult(ctx->T,ctx->x2,ctx->y2);CHKERRQ(ierr);
  ierr = VecScale(ctx->y2,ctx->tau2);CHKERRQ(ierr);
  ierr = VecScale(ctx->y2,ctx->tau2);CHKERRQ(ierr);
  ierr = VecAXPY(ctx->y2,-ctx->beta,ctx->x1);CHKERRQ(ierr);
  ierr = VecAXPY(ctx->y2,-ctx->beta,ctx->x1);CHKERRQ(ierr);
  ierr = VecAXPY(ctx->y2,-ctx->alpha * ctx->alpha + ctx->sigma,ctx->x2);CHKERRQ(ierr);
  ierr = VecAXPY(ctx->y2,-ctx->alpha * ctx->alpha + ctx->sigma,ctx->x2);CHKERRQ(ierr);
 
 
  ierr = VecRestoreArray(x,&px);CHKERRQ(ierr);
  ierr = VecRestoreArray(x,&px);CHKERRQ(ierr);
  ierr = VecRestoreArray(y,&py);CHKERRQ(ierr);
  ierr = VecRestoreArray(y,&py);CHKERRQ(ierr);
  ierr = VecResetArray(ctx->x1);CHKERRQ(ierr);
  ierr = VecResetArray(ctx->x1);CHKERRQ(ierr);
  ierr = VecResetArray(ctx->x2);CHKERRQ(ierr);
  ierr = VecResetArray(ctx->x2);CHKERRQ(ierr);
  ierr = VecResetArray(ctx->y1);CHKERRQ(ierr);
  ierr = VecResetArray(ctx->y1);CHKERRQ(ierr);
  ierr = VecResetArray(ctx->y2);CHKERRQ(ierr);
  ierr = VecResetArray(ctx->y2);CHKERRQ(ierr);
  PetscFunctionReturn(0);
  PetscFunctionReturn(0);
}
}
 
 
#undef __FUNCT__
#undef __FUNCT__
#define __FUNCT__ "MatBrussel_Shift"
#define __FUNCT__ "MatBrussel_Shift"
PetscErrorCode MatBrussel_Shift( PetscScalar* a, Mat Y )
PetscErrorCode MatBrussel_Shift( PetscScalar* a, Mat Y )
{
{
  CTX_BRUSSEL    *ctx;
  CTX_BRUSSEL    *ctx;
  PetscErrorCode ierr;
  PetscErrorCode ierr;
 
 
  PetscFunctionBegin;
  PetscFunctionBegin;
  ierr = MatShellGetContext( Y, (void**)&ctx ); CHKERRQ(ierr);
  ierr = MatShellGetContext( Y, (void**)&ctx ); CHKERRQ(ierr);
  ctx->sigma += *a;
  ctx->sigma += *a;
  PetscFunctionReturn(0);
  PetscFunctionReturn(0);
}
}
 
 
#undef __FUNCT__
#undef __FUNCT__
#define __FUNCT__ "MatBrussel_GetDiagonal"
#define __FUNCT__ "MatBrussel_GetDiagonal"
int MatBrussel_GetDiagonal(Mat A,Vec diag)
int MatBrussel_GetDiagonal(Mat A,Vec diag)
{
{
  Vec            d1, d2;
  Vec            d1, d2;
  PetscErrorCode ierr;
  PetscErrorCode ierr;
  PetscInt       n;
  PetscInt       n;
  PetscScalar    *pd;
  PetscScalar    *pd;
  MPI_Comm       comm;
  MPI_Comm       comm;
  CTX_BRUSSEL    *ctx;
  CTX_BRUSSEL    *ctx;
 
 
  PetscFunctionBegin;
  PetscFunctionBegin;
  ierr = MatShellGetContext(A,(void**)&ctx);CHKERRQ(ierr);
  ierr = MatShellGetContext(A,(void**)&ctx);CHKERRQ(ierr);
  ierr = PetscObjectGetComm((PetscObject)A,&comm);CHKERRQ(ierr);
  ierr = PetscObjectGetComm((PetscObject)A,&comm);CHKERRQ(ierr);
  ierr = MatGetLocalSize(ctx->T,&n,PETSC_NULL);CHKERRQ(ierr);
  ierr = MatGetLocalSize(ctx->T,&n,PETSC_NULL);CHKERRQ(ierr);
  ierr = VecGetArray(diag,&pd);CHKERRQ(ierr);
  ierr = VecGetArray(diag,&pd);CHKERRQ(ierr);
  ierr = VecCreateMPIWithArray(comm,n,PETSC_DECIDE,pd,&d1);CHKERRQ(ierr);
  ierr = VecCreateMPIWithArray(comm,n,PETSC_DECIDE,pd,&d1);CHKERRQ(ierr);
  ierr = VecCreateMPIWithArray(comm,n,PETSC_DECIDE,pd+n,&d2);CHKERRQ(ierr);
  ierr = VecCreateMPIWithArray(comm,n,PETSC_DECIDE,pd+n,&d2);CHKERRQ(ierr);
 
 
  ierr = VecSet(d1,-2.0*ctx->tau1 + ctx->beta - 1.0 + ctx->sigma);CHKERRQ(ierr);
  ierr = VecSet(d1,-2.0*ctx->tau1 + ctx->beta - 1.0 + ctx->sigma);CHKERRQ(ierr);
  ierr = VecSet(d2,-2.0*ctx->tau2 - ctx->alpha*ctx->alpha + ctx->sigma);CHKERRQ(ierr);
  ierr = VecSet(d2,-2.0*ctx->tau2 - ctx->alpha*ctx->alpha + ctx->sigma);CHKERRQ(ierr);
 
 
  ierr = VecDestroy(d1);CHKERRQ(ierr);
  ierr = VecDestroy(d1);CHKERRQ(ierr);
  ierr = VecDestroy(d2);CHKERRQ(ierr);
  ierr = VecDestroy(d2);CHKERRQ(ierr);
  ierr = VecRestoreArray(diag,&pd);CHKERRQ(ierr);
  ierr = VecRestoreArray(diag,&pd);CHKERRQ(ierr);
  PetscFunctionReturn(0);
  PetscFunctionReturn(0);
}
}