C++ CHKERRQ函数代码示例

PetscErrorCode  TSGLAdaptCreate(MPI_Comm comm,TSGLAdapt *inadapt)
{
  PetscErrorCode ierr;
  TSGLAdapt      adapt;

  PetscFunctionBegin;
  *inadapt = NULL;
  ierr     = PetscHeaderCreate(adapt,TSGLADAPT_CLASSID,"TSGLAdapt","General Linear adaptivity","TS",comm,TSGLAdaptDestroy,TSGLAdaptView);CHKERRQ(ierr);
  *inadapt = adapt;
  PetscFunctionReturn(0);
}

PetscErrorCode  PetscViewerFileSetName_ASCII(PetscViewer viewer,const char name[])
{
  PetscErrorCode    ierr;
  size_t            len;
  char              fname[PETSC_MAX_PATH_LEN],*gz;
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII*)viewer->data;
  PetscBool         isstderr,isstdout;
  PetscMPIInt       rank;

  PetscFunctionBegin;
  ierr = PetscViewerFileClose_ASCII(viewer);CHKERRQ(ierr);
  if (!name) PetscFunctionReturn(0);
  ierr = PetscStrallocpy(name,&vascii->filename);CHKERRQ(ierr);

  /* Is this file to be compressed */
  vascii->storecompressed = PETSC_FALSE;

  ierr = PetscStrstr(vascii->filename,".gz",&gz);CHKERRQ(ierr);
  if (gz) {
    ierr = PetscStrlen(gz,&len);CHKERRQ(ierr);
    if (len == 3) {
      *gz = 0;
      vascii->storecompressed = PETSC_TRUE;
    }
  }
  ierr = MPI_Comm_rank(PetscObjectComm((PetscObject)viewer),&rank);CHKERRQ(ierr);
  if (!rank) {
    ierr = PetscStrcmp(name,"stderr",&isstderr);CHKERRQ(ierr);
    ierr = PetscStrcmp(name,"stdout",&isstdout);CHKERRQ(ierr);
    /* empty filename means stdout */
    if (name[0] == 0)  isstdout = PETSC_TRUE;
    if (isstderr)      vascii->fd = PETSC_STDERR;
    else if (isstdout) vascii->fd = PETSC_STDOUT;
    else {


      ierr = PetscFixFilename(name,fname);CHKERRQ(ierr);
      switch (vascii->mode) {
      case FILE_MODE_READ:
        vascii->fd = fopen(fname,"r");
        break;
      case FILE_MODE_WRITE:
        vascii->fd = fopen(fname,"w");
        break;
      case FILE_MODE_APPEND:
        vascii->fd = fopen(fname,"a");
        break;
      case FILE_MODE_UPDATE:
        vascii->fd = fopen(fname,"r+");
        if (!vascii->fd) vascii->fd = fopen(fname,"w+");
        break;
      case FILE_MODE_APPEND_UPDATE:
        /* I really want a file which is opened at the end for updating,
           not a+, which opens at the beginning, but makes writes at the end.
        */
        vascii->fd = fopen(fname,"r+");
        if (!vascii->fd) vascii->fd = fopen(fname,"w+");
        else {
          ierr     = fseek(vascii->fd, 0, SEEK_END);CHKERRQ(ierr);
        }
        break;
      default:
        SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG, "Invalid file mode %d", vascii->mode);
      }
      if (!vascii->fd) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_FILE_OPEN,"Cannot open PetscViewer file: %s",fname);
    }
  }
#if defined(PETSC_USE_LOG)
  PetscLogObjectState((PetscObject)viewer,"File: %s",name);
#endif
  PetscFunctionReturn(0);
}

PetscErrorCode PetscViewerDestroy_ASCII_Subcomm(PetscViewer viewer)
{
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII*)viewer->data;
  PetscErrorCode    ierr;

  PetscFunctionBegin;
  ierr = PetscViewerRestoreSubcomm(vascii->subviewer,PetscObjectComm((PetscObject)viewer),&viewer);CHKERRQ(ierr);
  vascii->subviewer = NULL;
  PetscFunctionReturn(0);
}

EXTERN_C_END

#undef __FUNCT__
#define __FUNCT__ "PetscViewerRegisterAll"
/*@C
  PetscViewerRegisterAll - Registers all of the graphics methods in the PetscViewer package.

  Not Collective

   Level: developer

.seealso:  PetscViewerRegisterDestroy()
@*/
PetscErrorCode  PetscViewerRegisterAll(const char *path)
{
  PetscErrorCode ierr;

  PetscFunctionBegin;
  ierr = PetscViewerRegisterDynamic(PETSCVIEWERASCII,      path,"PetscViewerCreate_ASCII",      PetscViewerCreate_ASCII);CHKERRQ(ierr);
  ierr = PetscViewerRegisterDynamic(PETSCVIEWERBINARY,     path,"PetscViewerCreate_Binary",     PetscViewerCreate_Binary);CHKERRQ(ierr);
  ierr = PetscViewerRegisterDynamic(PETSCVIEWERSTRING,     path,"PetscViewerCreate_String",     PetscViewerCreate_String);CHKERRQ(ierr);
  ierr = PetscViewerRegisterDynamic(PETSCVIEWERDRAW,       path,"PetscViewerCreate_Draw",       PetscViewerCreate_Draw);CHKERRQ(ierr);
#if defined(PETSC_USE_SOCKET_VIEWER)
  ierr = PetscViewerRegisterDynamic(PETSCVIEWERSOCKET,     path,"PetscViewerCreate_Socket",     PetscViewerCreate_Socket);CHKERRQ(ierr);
#endif
#if defined(PETSC_HAVE_MATHEMATICA)
  ierr = PetscViewerRegisterDynamic(PETSCVIEWERMATHEMATICA,path,"PetscViewerCreate_Mathematica",PetscViewerCreate_Mathematica);CHKERRQ(ierr);
#endif
  ierr = PetscViewerRegisterDynamic(PETSCVIEWERVU,         path,"PetscViewerCreate_VU",         PetscViewerCreate_VU);CHKERRQ(ierr);
#if defined(PETSC_HAVE_HDF5)
  ierr = PetscViewerRegisterDynamic(PETSCVIEWERHDF5,       path,"PetscViewerCreate_HDF5",       PetscViewerCreate_HDF5);CHKERRQ(ierr);
#endif
#if defined(PETSC_HAVE_MATLAB_ENGINE)
  ierr = PetscViewerRegisterDynamic(PETSCVIEWERMATLAB,     path,"PetscViewerCreate_Matlab",     PetscViewerCreate_Matlab);CHKERRQ(ierr);
#endif
#if defined(PETSC_HAVE_AMS)
  ierr = PetscViewerRegisterDynamic(PETSCVIEWERAMS,        path,"PetscViewerCreate_AMS",        PetscViewerCreate_AMS);CHKERRQ(ierr);
#endif
  ierr = PetscViewerRegisterDynamic(PETSCVIEWERVTK,        path,"PetscViewerCreate_VTK",        PetscViewerCreate_VTK);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

/*@C
    PetscViewerASCIIPrintf - Prints to a file, only from the first
    processor in the PetscViewer

    Not Collective, but only first processor in set has any effect

    Input Parameters:
+    viewer - optained with PetscViewerASCIIOpen()
-    format - the usual printf() format string

    Level: developer

    Fortran Note:
    The call sequence is PetscViewerASCIIPrintf(PetscViewer, character(*), int ierr) from Fortran.
    That is, you can only pass a single character string from Fortran.

  Concepts: PetscViewerASCII^printing
  Concepts: printing^to file
  Concepts: printf

.seealso: PetscPrintf(), PetscSynchronizedPrintf(), PetscViewerASCIIOpen(),
          PetscViewerASCIIPushTab(), PetscViewerASCIIPopTab(), PetscViewerASCIISynchronizedPrintf(),
          PetscViewerCreate(), PetscViewerDestroy(), PetscViewerSetType(), PetscViewerASCIIGetPointer(), PetscViewerASCIISynchronizedAllow()
@*/
PetscErrorCode  PetscViewerASCIIPrintf(PetscViewer viewer,const char format[],...)
{
  PetscViewer_ASCII *ascii = (PetscViewer_ASCII*)viewer->data;
  PetscMPIInt       rank;
  PetscInt          tab,intab = ascii->tab;
  PetscErrorCode    ierr;
  FILE              *fd = ascii->fd;
  PetscBool         iascii,issingleton = PETSC_FALSE;
  int               err;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,1);
  PetscValidCharPointer(format,2);
  ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr);
  if (!iascii) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Not ASCII PetscViewer");
  if (ascii->bviewer) {
    viewer      = ascii->bviewer;
    ascii       = (PetscViewer_ASCII*)viewer->data;
    fd          = ascii->fd;
    issingleton = PETSC_TRUE;
  }

  ierr = MPI_Comm_rank(PetscObjectComm((PetscObject)viewer),&rank);CHKERRQ(ierr);
  if (!rank) {
    va_list Argp;
    tab = intab;
    while (tab--) {
      ierr = PetscFPrintf(PETSC_COMM_SELF,fd,"  ");CHKERRQ(ierr);
    }

    va_start(Argp,format);
    ierr = (*PetscVFPrintf)(fd,format,Argp);CHKERRQ(ierr);
    err  = fflush(fd);
    if (err) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SYS,"fflush() failed on file");
    if (petsc_history) {
      va_start(Argp,format);
      tab = intab;
      while (tab--) {
        ierr = PetscFPrintf(PETSC_COMM_SELF,petsc_history,"  ");CHKERRQ(ierr);
      }
      ierr = (*PetscVFPrintf)(petsc_history,format,Argp);CHKERRQ(ierr);
      err  = fflush(petsc_history);
      if (err) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SYS,"fflush() failed on file");
    }
    va_end(Argp);
  } else if (issingleton) {
    char        *string;
    va_list     Argp;
    size_t      fullLength;
    PrintfQueue next;

    ierr = PetscNew(&next);CHKERRQ(ierr);
    if (petsc_printfqueue) {
      petsc_printfqueue->next = next;
      petsc_printfqueue       = next;
    } else {
      petsc_printfqueuebase = petsc_printfqueue = next;
    }
    petsc_printfqueuelength++;
    next->size = QUEUESTRINGSIZE;
    ierr       = PetscCalloc1(next->size, &next->string);CHKERRQ(ierr);
    string     = next->string;
    tab        = intab;
    tab       *= 2;
    while (tab--) {
      *string++ = ' ';
    }
    va_start(Argp,format);
    ierr = PetscVSNPrintf(string,next->size-2*ascii->tab,format,&fullLength,Argp);CHKERRQ(ierr);
    va_end(Argp);
  }
  PetscFunctionReturn(0);
}

int main(int argc, char *argv[])
{
  PetscErrorCode ierr;
  DM             dau,dak,pack;
  const PetscInt *lxu;
  PetscInt       *lxk,m,sizes;
  User           user;
  SNES           snes;
  Vec            X,F,Xu,Xk,Fu,Fk;
  Mat            B;
  IS             *isg;
  PetscBool      view_draw,pass_dm;

  PetscInitialize(&argc,&argv,0,help);
  ierr = DMDACreate1d(PETSC_COMM_WORLD,DM_BOUNDARY_NONE,-10,1,1,NULL,&dau);CHKERRQ(ierr);
  ierr = DMSetOptionsPrefix(dau,"u_");CHKERRQ(ierr);
  ierr = DMSetFromOptions(dau);CHKERRQ(ierr);
  ierr = DMDAGetOwnershipRanges(dau,&lxu,0,0);CHKERRQ(ierr);
  ierr = DMDAGetInfo(dau,0, &m,0,0, &sizes,0,0, 0,0,0,0,0,0);CHKERRQ(ierr);
  ierr = PetscMalloc1(sizes,&lxk);CHKERRQ(ierr);
  ierr = PetscMemcpy(lxk,lxu,sizes*sizeof(*lxk));CHKERRQ(ierr);
  lxk[0]--;
  ierr = DMDACreate1d(PETSC_COMM_WORLD,DM_BOUNDARY_NONE,m-1,1,1,lxk,&dak);CHKERRQ(ierr);
  ierr = DMSetOptionsPrefix(dak,"k_");CHKERRQ(ierr);
  ierr = DMSetFromOptions(dak);CHKERRQ(ierr);
  ierr = PetscFree(lxk);CHKERRQ(ierr);

  ierr = DMCompositeCreate(PETSC_COMM_WORLD,&pack);CHKERRQ(ierr);
  ierr = DMSetOptionsPrefix(pack,"pack_");CHKERRQ(ierr);
  ierr = DMCompositeAddDM(pack,dau);CHKERRQ(ierr);
  ierr = DMCompositeAddDM(pack,dak);CHKERRQ(ierr);
  ierr = DMDASetFieldName(dau,0,"u");CHKERRQ(ierr);
  ierr = DMDASetFieldName(dak,0,"k");CHKERRQ(ierr);
  ierr = DMSetFromOptions(pack);CHKERRQ(ierr);

  ierr = DMCreateGlobalVector(pack,&X);CHKERRQ(ierr);
  ierr = VecDuplicate(X,&F);CHKERRQ(ierr);

  ierr = PetscNew(&user);CHKERRQ(ierr);

  user->pack = pack;

  ierr = DMCompositeGetGlobalISs(pack,&isg);CHKERRQ(ierr);
  ierr = DMCompositeGetLocalVectors(pack,&user->Uloc,&user->Kloc);CHKERRQ(ierr);
  ierr = DMCompositeScatter(pack,X,user->Uloc,user->Kloc);CHKERRQ(ierr);

  ierr = PetscOptionsBegin(PETSC_COMM_WORLD,NULL,"Coupled problem options","SNES");CHKERRQ(ierr);
  {
    user->ptype = 0; view_draw = PETSC_FALSE; pass_dm = PETSC_TRUE;

    ierr = PetscOptionsInt("-problem_type","0: solve for u only, 1: solve for k only, 2: solve for both",0,user->ptype,&user->ptype,NULL);CHKERRQ(ierr);
    ierr = PetscOptionsBool("-view_draw","Draw the final coupled solution regardless of whether only one physics was solved",0,view_draw,&view_draw,NULL);CHKERRQ(ierr);
    ierr = PetscOptionsBool("-pass_dm","Pass the packed DM to SNES to use when determining splits and forward into splits",0,pass_dm,&pass_dm,NULL);CHKERRQ(ierr);
  }
  ierr = PetscOptionsEnd();CHKERRQ(ierr);

  ierr = FormInitial_Coupled(user,X);CHKERRQ(ierr);

  ierr = SNESCreate(PETSC_COMM_WORLD,&snes);CHKERRQ(ierr);
  switch (user->ptype) {
  case 0:
    ierr = DMCompositeGetAccess(pack,X,&Xu,0);CHKERRQ(ierr);
    ierr = DMCompositeGetAccess(pack,F,&Fu,0);CHKERRQ(ierr);
    ierr = DMCreateMatrix(dau,&B);CHKERRQ(ierr);
    ierr = SNESSetFunction(snes,Fu,FormFunction_All,user);CHKERRQ(ierr);
    ierr = SNESSetJacobian(snes,B,B,FormJacobian_All,user);CHKERRQ(ierr);
    ierr = SNESSetFromOptions(snes);CHKERRQ(ierr);
    ierr = SNESSetDM(snes,dau);CHKERRQ(ierr);
    ierr = SNESSolve(snes,NULL,Xu);CHKERRQ(ierr);
    ierr = DMCompositeRestoreAccess(pack,X,&Xu,0);CHKERRQ(ierr);
    ierr = DMCompositeRestoreAccess(pack,F,&Fu,0);CHKERRQ(ierr);
    break;
  case 1:
    ierr = DMCompositeGetAccess(pack,X,0,&Xk);CHKERRQ(ierr);
    ierr = DMCompositeGetAccess(pack,F,0,&Fk);CHKERRQ(ierr);
    ierr = DMCreateMatrix(dak,&B);CHKERRQ(ierr);
    ierr = SNESSetFunction(snes,Fk,FormFunction_All,user);CHKERRQ(ierr);
    ierr = SNESSetJacobian(snes,B,B,FormJacobian_All,user);CHKERRQ(ierr);
    ierr = SNESSetFromOptions(snes);CHKERRQ(ierr);
    ierr = SNESSetDM(snes,dak);CHKERRQ(ierr);
    ierr = SNESSolve(snes,NULL,Xk);CHKERRQ(ierr);
    ierr = DMCompositeRestoreAccess(pack,X,0,&Xk);CHKERRQ(ierr);
    ierr = DMCompositeRestoreAccess(pack,F,0,&Fk);CHKERRQ(ierr);
    break;
  case 2:
    ierr = DMCreateMatrix(pack,&B);CHKERRQ(ierr);
    /* This example does not correctly allocate off-diagonal blocks. These options allows new nonzeros (slow). */
    ierr = MatSetOption(B,MAT_NEW_NONZERO_LOCATION_ERR,PETSC_FALSE);CHKERRQ(ierr);
    ierr = MatSetOption(B,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_FALSE);CHKERRQ(ierr);
    ierr = SNESSetFunction(snes,F,FormFunction_All,user);CHKERRQ(ierr);
    ierr = SNESSetJacobian(snes,B,B,FormJacobian_All,user);CHKERRQ(ierr);
    ierr = SNESSetFromOptions(snes);CHKERRQ(ierr);
    if (!pass_dm) {             /* Manually provide index sets and names for the splits */
      KSP ksp;
      PC  pc;
      ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
      ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
      ierr = PCFieldSplitSetIS(pc,"u",isg[0]);CHKERRQ(ierr);
      ierr = PCFieldSplitSetIS(pc,"k",isg[1]);CHKERRQ(ierr);
    } else {
//.........这里部分代码省略.........

int main(int argc,char **argv)
{
  TS             ts;            /* time integration context */
  Vec            X;             /* solution, residual vectors */
  Mat            J;             /* Jacobian matrix */
  PetscErrorCode ierr;
  PetscScalar    *x;
  PetscReal      ftime;
  PetscInt       i,steps,nits,lits;
  PetscBool      view_final;
  Ctx            ctx;

  PetscInitialize(&argc,&argv,(char *)0,help);
  ctx.n = 3;
  ierr = PetscOptionsGetInt(PETSC_NULL,"-n",&ctx.n,PETSC_NULL);CHKERRQ(ierr);
  if (ctx.n < 2) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_ARG_OUTOFRANGE,"The dimension specified with -n must be at least 2");
  view_final = PETSC_FALSE;
  ierr = PetscOptionsGetBool(PETSC_NULL,"-view_final",&view_final,PETSC_NULL);CHKERRQ(ierr);
  ctx.monitor_short = PETSC_FALSE;
  ierr = PetscOptionsGetBool(PETSC_NULL,"-monitor_short",&ctx.monitor_short,PETSC_NULL);CHKERRQ(ierr);

  /*
     Create Jacobian matrix data structure and state vector
  */
  ierr = MatCreate(PETSC_COMM_WORLD,&J);CHKERRQ(ierr);
  ierr = MatSetSizes(J,PETSC_DECIDE,PETSC_DECIDE,ctx.n,ctx.n);CHKERRQ(ierr);
  ierr = MatSetFromOptions(J);CHKERRQ(ierr);
  ierr = MatSetUp(J);CHKERRQ(ierr);
  ierr = MatGetVecs(J,&X,PETSC_NULL);CHKERRQ(ierr);

  /* Create time integration context */
  ierr = TSCreate(PETSC_COMM_WORLD,&ts);CHKERRQ(ierr);
  ierr = TSSetType(ts,TSPSEUDO);CHKERRQ(ierr);
  ierr = TSSetIFunction(ts,PETSC_NULL,FormIFunction,&ctx);CHKERRQ(ierr);
  ierr = TSSetIJacobian(ts,J,J,FormIJacobian,&ctx);CHKERRQ(ierr);
  ierr = TSSetDuration(ts,1000,1e14);CHKERRQ(ierr);
  ierr = TSSetInitialTimeStep(ts,0.0,1e-3);CHKERRQ(ierr);
  ierr = TSMonitorSet(ts,MonitorObjective,&ctx,PETSC_NULL);CHKERRQ(ierr);

  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     Customize time integrator; set runtime options
   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  ierr = TSSetFromOptions(ts);CHKERRQ(ierr);

  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     Evaluate initial guess; then solve nonlinear system
   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  ierr = VecSet(X,0.0);CHKERRQ(ierr);
  ierr = VecGetArray(X,&x);CHKERRQ(ierr);
#if 1
  x[0] = 5.;
  x[1] = -5.;
  for (i=2; i<ctx.n; i++) x[i] = 5.;
#else
  x[0] = 1.0;
  x[1] = 15.0;
  for (i=2; i<ctx.n; i++) x[i] = 10.0;
#endif
  ierr = VecRestoreArray(X,&x);CHKERRQ(ierr);

  ierr = TSSolve(ts,X);CHKERRQ(ierr);
  ierr = TSGetSolveTime(ts,&ftime);CHKERRQ(ierr);
  ierr = TSGetTimeStepNumber(ts,&steps);CHKERRQ(ierr);
  ierr = TSGetSNESIterations(ts,&nits);CHKERRQ(ierr);
  ierr = TSGetKSPIterations(ts,&lits);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Time integrator took (%D,%D,%D) iterations to reach final time %G\n",steps,nits,lits,ftime);CHKERRQ(ierr);
  if (view_final) {
    ierr = VecView(X,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
  }

  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     Free work space.  All PETSc objects should be destroyed when they
     are no longer needed.
   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

  ierr = VecDestroy(&X);CHKERRQ(ierr);
  ierr = MatDestroy(&J);CHKERRQ(ierr);
  ierr = TSDestroy(&ts);CHKERRQ(ierr);
  ierr = PetscFinalize();
  return 0;
}

PetscErrorCode KSPSolve_STCG(KSP ksp)
{
#ifdef PETSC_USE_COMPLEX
  SETERRQ(((PetscObject)ksp)->comm,PETSC_ERR_SUP, "STCG is not available for complex systems");
#else
  KSP_STCG       *cg = (KSP_STCG *)ksp->data;

  PetscErrorCode ierr;
  MatStructure   pflag;
  Mat            Qmat, Mmat;
  Vec            r, z, p, d;
  PC             pc;

  PetscReal      norm_r, norm_d, norm_dp1, norm_p, dMp;
  PetscReal      alpha, beta, kappa, rz, rzm1;
  PetscReal      rr, r2, step;

  PetscInt       max_cg_its;

  PetscBool      diagonalscale;

  PetscFunctionBegin;
  /***************************************************************************/
  /* Check the arguments and parameters.                                     */
  /***************************************************************************/

  ierr = PCGetDiagonalScale(ksp->pc, &diagonalscale);CHKERRQ(ierr);
  if (diagonalscale) SETERRQ1(((PetscObject)ksp)->comm,PETSC_ERR_SUP, "Krylov method %s does not support diagonal scaling", ((PetscObject)ksp)->type_name);
  if (cg->radius < 0.0) SETERRQ(((PetscObject)ksp)->comm,PETSC_ERR_ARG_OUTOFRANGE, "Input error: radius < 0");

  /***************************************************************************/
  /* Get the workspace vectors and initialize variables                      */
  /***************************************************************************/

  r2 = cg->radius * cg->radius;
  r  = ksp->work[0];
  z  = ksp->work[1];
  p  = ksp->work[2];
  d  = ksp->vec_sol;
  pc = ksp->pc;

  ierr = PCGetOperators(pc, &Qmat, &Mmat, &pflag);CHKERRQ(ierr);

  ierr = VecGetSize(d, &max_cg_its);CHKERRQ(ierr);
  max_cg_its = PetscMin(max_cg_its, ksp->max_it);
  ksp->its = 0;

  /***************************************************************************/
  /* Initialize objective function and direction.                            */
  /***************************************************************************/

  cg->o_fcn = 0.0;

  ierr = VecSet(d, 0.0);CHKERRQ(ierr);			/* d = 0             */
  cg->norm_d = 0.0;

  /***************************************************************************/
  /* Begin the conjugate gradient method.  Check the right-hand side for     */
  /* numerical problems.  The check for not-a-number and infinite values     */
  /* need be performed only once.                                            */
  /***************************************************************************/

  ierr = VecCopy(ksp->vec_rhs, r);CHKERRQ(ierr);	/* r = -grad         */
  ierr = VecDot(r, r, &rr);CHKERRQ(ierr);		/* rr = r^T r        */
  if (PetscIsInfOrNanScalar(rr)) {
    /*************************************************************************/
    /* The right-hand side contains not-a-number or an infinite value.       */
    /* The gradient step does not work; return a zero value for the step.    */
    /*************************************************************************/

    ksp->reason = KSP_DIVERGED_NAN;
    ierr = PetscInfo1(ksp, "KSPSolve_STCG: bad right-hand side: rr=%g\n", rr);CHKERRQ(ierr);
    PetscFunctionReturn(0);
  }

  /***************************************************************************/
  /* Check the preconditioner for numerical problems and for positive        */
  /* definiteness.  The check for not-a-number and infinite values need be   */
  /* performed only once.                                                    */
  /***************************************************************************/

  ierr = KSP_PCApply(ksp, r, z);CHKERRQ(ierr);		/* z = inv(M) r      */
  ierr = VecDot(r, z, &rz);CHKERRQ(ierr);		/* rz = r^T inv(M) r */
  if (PetscIsInfOrNanScalar(rz)) {
    /*************************************************************************/
    /* The preconditioner contains not-a-number or an infinite value.        */
    /* Return the gradient direction intersected with the trust region.      */
    /*************************************************************************/

    ksp->reason = KSP_DIVERGED_NAN;
    ierr = PetscInfo1(ksp, "KSPSolve_STCG: bad preconditioner: rz=%g\n", rz);CHKERRQ(ierr);

    if (cg->radius != 0) {
      if (r2 >= rr) {
        alpha = 1.0;
        cg->norm_d = PetscSqrtReal(rr);
      }
      else {
        alpha = PetscSqrtReal(r2 / rr);
        cg->norm_d = cg->radius;
//.........这里部分代码省略.........

PetscErrorCode MatSetUpMultiply_MPISBAIJ(Mat mat)
{
  Mat_MPISBAIJ   *sbaij = (Mat_MPISBAIJ*)mat->data;
  Mat_SeqBAIJ    *B = (Mat_SeqBAIJ*)(sbaij->B->data);  
  PetscErrorCode ierr;
  PetscInt       Nbs = sbaij->Nbs,i,j,*indices,*aj = B->j,ec = 0,*garray,*sgarray;
  PetscInt       bs = mat->rmap->bs,*stmp,mbs=sbaij->mbs, vec_size,nt;
  IS             from,to;
  Vec            gvec;
  PetscMPIInt    rank=sbaij->rank,lsize,size=sbaij->size; 
  PetscInt       *owners=sbaij->rangebs,*sowners,*ec_owner,k; 
  PetscScalar    *ptr;

  PetscFunctionBegin;
  ierr = VecScatterDestroy(&sbaij->sMvctx);CHKERRQ(ierr);
  
  /* For the first stab we make an array as long as the number of columns */
  /* mark those columns that are in sbaij->B */
  ierr = PetscMalloc(Nbs*sizeof(PetscInt),&indices);CHKERRQ(ierr);
  ierr = PetscMemzero(indices,Nbs*sizeof(PetscInt));CHKERRQ(ierr);
  for (i=0; i<mbs; i++) {
    for (j=0; j<B->ilen[i]; j++) {
      if (!indices[aj[B->i[i] + j]]) ec++; 
      indices[aj[B->i[i] + j] ] = 1;
    }
  }

  /* form arrays of columns we need */
  ierr = PetscMalloc(ec*sizeof(PetscInt),&garray);CHKERRQ(ierr);
  ierr = PetscMalloc2(2*ec,PetscInt,&sgarray,ec,PetscInt,&ec_owner);CHKERRQ(ierr);
  
  ec = 0;
  for (j=0; j<size; j++){
    for (i=owners[j]; i<owners[j+1]; i++){
      if (indices[i]) {
        garray[ec]   = i;
        ec_owner[ec] = j;
        ec++;
      }
    }
  }

  /* make indices now point into garray */
  for (i=0; i<ec; i++) indices[garray[i]] = i;

  /* compact out the extra columns in B */
  for (i=0; i<mbs; i++) {
    for (j=0; j<B->ilen[i]; j++) aj[B->i[i] + j] = indices[aj[B->i[i] + j]];
  }
  B->nbs      = ec;
  sbaij->B->cmap->n = sbaij->B->cmap->N = ec*mat->rmap->bs;
  ierr = PetscLayoutSetUp((sbaij->B->cmap));CHKERRQ(ierr);
  ierr = PetscFree(indices);CHKERRQ(ierr);

  /* create local vector that is used to scatter into */
  ierr = VecCreateSeq(PETSC_COMM_SELF,ec*bs,&sbaij->lvec);CHKERRQ(ierr);

  /* create two temporary index sets for building scatter-gather */
  ierr = PetscMalloc(2*ec*sizeof(PetscInt),&stmp);CHKERRQ(ierr);
  ierr = ISCreateBlock(PETSC_COMM_SELF,bs,ec,garray,PETSC_COPY_VALUES,&from);CHKERRQ(ierr);   
  for (i=0; i<ec; i++) { stmp[i] = i; } 
  ierr = ISCreateBlock(PETSC_COMM_SELF,bs,ec,stmp,PETSC_COPY_VALUES,&to);CHKERRQ(ierr);

  /* generate the scatter context 
     -- Mvctx and lvec are not used by MatMult_MPISBAIJ(), but usefule for some applications */
  ierr = VecCreateMPIWithArray(((PetscObject)mat)->comm,1,mat->cmap->n,mat->cmap->N,PETSC_NULL,&gvec);CHKERRQ(ierr);
  ierr = VecScatterCreate(gvec,from,sbaij->lvec,to,&sbaij->Mvctx);CHKERRQ(ierr); 
  ierr = VecDestroy(&gvec);CHKERRQ(ierr);

  sbaij->garray = garray;
  ierr = PetscLogObjectParent(mat,sbaij->Mvctx);CHKERRQ(ierr);
  ierr = PetscLogObjectParent(mat,sbaij->lvec);CHKERRQ(ierr);
  ierr = PetscLogObjectParent(mat,from);CHKERRQ(ierr);
  ierr = PetscLogObjectParent(mat,to);CHKERRQ(ierr);

  ierr = ISDestroy(&from);CHKERRQ(ierr);
  ierr = ISDestroy(&to);CHKERRQ(ierr);

  /* create parallel vector that is used by SBAIJ matrix to scatter from/into */
  lsize = (mbs + ec)*bs;
  ierr = VecCreateMPI(((PetscObject)mat)->comm,lsize,PETSC_DETERMINE,&sbaij->slvec0);CHKERRQ(ierr);
  ierr = VecDuplicate(sbaij->slvec0,&sbaij->slvec1);CHKERRQ(ierr);
  ierr = VecGetSize(sbaij->slvec0,&vec_size);CHKERRQ(ierr);

  sowners = sbaij->slvec0->map->range;
 
  /* x index in the IS sfrom */
  for (i=0; i<ec; i++) { 
    j = ec_owner[i];
    sgarray[i]  = garray[i] + (sowners[j]/bs - owners[j]);  
  } 
  /* b index in the IS sfrom */
  k = sowners[rank]/bs + mbs;
  for (i=ec,j=0; i< 2*ec; i++,j++) sgarray[i] = k + j;
  ierr = ISCreateBlock(PETSC_COMM_SELF,bs,2*ec,sgarray,PETSC_COPY_VALUES,&from);CHKERRQ(ierr);   
 
  /* x index in the IS sto */
  k = sowners[rank]/bs + mbs;
  for (i=0; i<ec; i++) stmp[i] = (k + i);  
  /* b index in the IS sto */
//.........这里部分代码省略.........

int main(int argc,char **argv)
{
  PetscErrorCode ierr;
  UserCtx        user;
  DM             red,da;
  SNES           snes;
  DM             packer;
  PetscBool      use_monitor = PETSC_FALSE;

  PetscInitialize(&argc,&argv,NULL,help);
  ierr = PetscOptionsSetFromOptions();CHKERRQ(ierr);

  /* Hardwire several options; can be changed at command line */
  ierr = PetscOptionsInsertString(common_options);CHKERRQ(ierr);
  ierr = PetscOptionsInsertString(matrix_free_options);CHKERRQ(ierr);
  ierr = PetscOptionsInsert(&argc,&argv,NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetBool(NULL,"-use_monitor",&use_monitor,PETSC_IGNORE);CHKERRQ(ierr);

  /* Create a global vector that includes a single redundant array and two da arrays */
  ierr = DMCompositeCreate(PETSC_COMM_WORLD,&packer);CHKERRQ(ierr);
  ierr = DMRedundantCreate(PETSC_COMM_WORLD,0,1,&red);CHKERRQ(ierr);
  ierr = DMSetOptionsPrefix(red,"red_");CHKERRQ(ierr);
  ierr = DMCompositeAddDM(packer,red);CHKERRQ(ierr);
  ierr = DMDACreate1d(PETSC_COMM_WORLD,DM_BOUNDARY_NONE,-5,2,1,NULL,&da);CHKERRQ(ierr);
  ierr = DMSetOptionsPrefix(red,"da_");CHKERRQ(ierr);
  ierr = DMCompositeAddDM(packer,(DM)da);CHKERRQ(ierr);
  ierr = DMSetApplicationContext(packer,&user);CHKERRQ(ierr);

  packer->ops->creatematrix = DMCreateMatrix_MF;

  /* create nonlinear multi-level solver */
  ierr = SNESCreate(PETSC_COMM_WORLD,&snes);CHKERRQ(ierr);
  ierr = SNESSetDM(snes,packer);CHKERRQ(ierr);
  ierr = SNESSetFunction(snes,NULL,ComputeFunction,NULL);CHKERRQ(ierr);
  ierr = SNESSetJacobian(snes,NULL, NULL,ComputeJacobian_MF,NULL);CHKERRQ(ierr);

  ierr = SNESSetFromOptions(snes);CHKERRQ(ierr);

  if (use_monitor) {
    /* create graphics windows */
    ierr = PetscViewerDrawOpen(PETSC_COMM_WORLD,0,"u_lambda - state variables and Lagrange multipliers",-1,-1,-1,-1,&user.u_lambda_viewer);CHKERRQ(ierr);
    ierr = PetscViewerDrawOpen(PETSC_COMM_WORLD,0,"fu_lambda - derivate w.r.t. state variables and Lagrange multipliers",-1,-1,-1,-1,&user.fu_lambda_viewer);CHKERRQ(ierr);
    ierr = SNESMonitorSet(snes,Monitor,0,0);CHKERRQ(ierr);
  }

  ierr = SNESSolve(snes,NULL,NULL);CHKERRQ(ierr);
  ierr = SNESDestroy(&snes);CHKERRQ(ierr);

  ierr = DMDestroy(&red);CHKERRQ(ierr);
  ierr = DMDestroy(&da);CHKERRQ(ierr);
  ierr = DMDestroy(&packer);CHKERRQ(ierr);
  if (use_monitor) {
    ierr = PetscViewerDestroy(&user.u_lambda_viewer);CHKERRQ(ierr);
    ierr = PetscViewerDestroy(&user.fu_lambda_viewer);CHKERRQ(ierr);
  }
  PetscFinalize();
  return 0;
}

PetscErrorCode Monitor(SNES snes,PetscInt its,PetscReal rnorm,void *dummy)
{
  UserCtx        *user;
  PetscErrorCode ierr;
  PetscInt       m,N;
  PetscScalar    *w,*dw;
  Vec            u_lambda,U,F,Uexact;
  DM             packer;
  PetscReal      norm;
  DM             da;

  PetscFunctionBeginUser;
  ierr = SNESGetDM(snes,&packer);CHKERRQ(ierr);
  ierr = DMGetApplicationContext(packer,&user);CHKERRQ(ierr);
  ierr = SNESGetSolution(snes,&U);CHKERRQ(ierr);
  ierr = DMCompositeGetAccess(packer,U,&w,&u_lambda);CHKERRQ(ierr);
  ierr = VecView(u_lambda,user->u_lambda_viewer);
  ierr = DMCompositeRestoreAccess(packer,U,&w,&u_lambda);CHKERRQ(ierr);

  ierr = SNESGetFunction(snes,&F,0,0);CHKERRQ(ierr);
  ierr = DMCompositeGetAccess(packer,F,&w,&u_lambda);CHKERRQ(ierr);
  /* ierr = VecView(u_lambda,user->fu_lambda_viewer); */
  ierr = DMCompositeRestoreAccess(packer,U,&w,&u_lambda);CHKERRQ(ierr);

  ierr = DMCompositeGetEntries(packer,&m,&da);CHKERRQ(ierr);
  ierr = DMDAGetInfo(da,0,&N,0,0,0,0,0,0,0,0,0,0,0);CHKERRQ(ierr);
  ierr = VecDuplicate(U,&Uexact);CHKERRQ(ierr);
  ierr = ExactSolution(packer,Uexact);CHKERRQ(ierr);
  ierr = VecAXPY(Uexact,-1.0,U);CHKERRQ(ierr);
  ierr = DMCompositeGetAccess(packer,Uexact,&dw,&u_lambda);CHKERRQ(ierr);
  ierr = VecStrideNorm(u_lambda,0,NORM_2,&norm);CHKERRQ(ierr);
  norm = norm/PetscSqrtReal((PetscReal)N-1.);
  if (dw) ierr = PetscPrintf(PETSC_COMM_WORLD,"Norm of error %g Error at x = 0 %g\n",(double)norm,(double)PetscRealPart(dw[0]));CHKERRQ(ierr);
  ierr = VecView(u_lambda,user->fu_lambda_viewer);
  ierr = DMCompositeRestoreAccess(packer,Uexact,&dw,&u_lambda);CHKERRQ(ierr);
  ierr = VecDestroy(&Uexact);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

/*
      Evaluates FU = Gradiant(L(w,u,lambda))

     This local function acts on the ghosted version of U (accessed via DMCompositeGetLocalVectors() and
   DMCompositeScatter()) BUT the global, nonghosted version of FU (via DMCompositeGetAccess()).

*/
PetscErrorCode ComputeFunction(SNES snes,Vec U,Vec FU,void *ctx)
{
  PetscErrorCode ierr;
  PetscInt       xs,xm,i,N;
  ULambda        *u_lambda,*fu_lambda;
  PetscScalar    d,h,*w,*fw;
  Vec            vw,vfw,vu_lambda,vfu_lambda;
  DM             packer,red,da;

  PetscFunctionBeginUser;
  ierr = VecGetDM(U, &packer);CHKERRQ(ierr);
  ierr = DMCompositeGetEntries(packer,&red,&da);CHKERRQ(ierr);
  ierr = DMCompositeGetLocalVectors(packer,&vw,&vu_lambda);CHKERRQ(ierr);
  ierr = DMCompositeScatter(packer,U,vw,vu_lambda);CHKERRQ(ierr);
  ierr = DMCompositeGetAccess(packer,FU,&vfw,&vfu_lambda);CHKERRQ(ierr);

  ierr = DMDAGetCorners(da,&xs,NULL,NULL,&xm,NULL,NULL);CHKERRQ(ierr);
  ierr = DMDAGetInfo(da,0,&N,0,0,0,0,0,0,0,0,0,0,0);CHKERRQ(ierr);
  ierr = VecGetArray(vw,&w);CHKERRQ(ierr);
  ierr = VecGetArray(vfw,&fw);CHKERRQ(ierr);
  ierr = DMDAVecGetArray(da,vu_lambda,&u_lambda);CHKERRQ(ierr);
  ierr = DMDAVecGetArray(da,vfu_lambda,&fu_lambda);CHKERRQ(ierr);
  d    = N-1.0;
  h    = 1.0/d;

  /* derivative of L() w.r.t. w */
  if (xs == 0) { /* only first processor computes this */
    fw[0] = -2.0*d*u_lambda[0].lambda;
  }

  /* derivative of L() w.r.t. u */
  for (i=xs; i<xs+xm; i++) {
    if      (i == 0)   fu_lambda[0].lambda   =    h*u_lambda[0].u   + 2.*d*u_lambda[0].lambda   - d*u_lambda[1].lambda;
    else if (i == 1)   fu_lambda[1].lambda   = 2.*h*u_lambda[1].u   + 2.*d*u_lambda[1].lambda   - d*u_lambda[2].lambda;
    else if (i == N-1) fu_lambda[N-1].lambda =    h*u_lambda[N-1].u + 2.*d*u_lambda[N-1].lambda - d*u_lambda[N-2].lambda;
    else if (i == N-2) fu_lambda[N-2].lambda = 2.*h*u_lambda[N-2].u + 2.*d*u_lambda[N-2].lambda - d*u_lambda[N-3].lambda;
    else               fu_lambda[i].lambda   = 2.*h*u_lambda[i].u   - d*(u_lambda[i+1].lambda - 2.0*u_lambda[i].lambda + u_lambda[i-1].lambda);
  }

  /* derivative of L() w.r.t. lambda */
  for (i=xs; i<xs+xm; i++) {
    if      (i == 0)   fu_lambda[0].u   = 2.0*d*(u_lambda[0].u - w[0]);
    else if (i == N-1) fu_lambda[N-1].u = 2.0*d*u_lambda[N-1].u;
    else               fu_lambda[i].u   = -(d*(u_lambda[i+1].u - 2.0*u_lambda[i].u + u_lambda[i-1].u) - 2.0*h);
  }

  ierr = VecRestoreArray(vw,&w);CHKERRQ(ierr);
  ierr = VecRestoreArray(vfw,&fw);CHKERRQ(ierr);
  ierr = DMDAVecRestoreArray(da,vu_lambda,&u_lambda);CHKERRQ(ierr);
  ierr = DMDAVecRestoreArray(da,vfu_lambda,&fu_lambda);CHKERRQ(ierr);
  ierr = DMCompositeRestoreLocalVectors(packer,&vw,&vu_lambda);CHKERRQ(ierr);
  ierr = DMCompositeRestoreAccess(packer,FU,&vfw,&vfu_lambda);CHKERRQ(ierr);
  ierr = PetscLogFlops(13.0*N);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

/*@
  TaoComputeObjectiveAndGradient - Computes the objective function value at a given point

  Collective on Tao

  Input Parameters:
+ tao - the Tao context
- X - input vector

  Output Parameter:
+ f - Objective value at X
- g - Gradient vector at X

  Notes: TaoComputeObjectiveAndGradient() is typically used within minimization implementations,
  so most users would not generally call this routine themselves.

  Level: advanced

.seealso: TaoComputeGradient(), TaoComputeObjectiveAndGradient(), TaoSetObjectiveRoutine()
@*/
PetscErrorCode TaoComputeObjectiveAndGradient(Tao tao, Vec X, PetscReal *f, Vec G)
{
    PetscErrorCode ierr;

    PetscFunctionBegin;
    PetscValidHeaderSpecific(tao,TAO_CLASSID,1);
    PetscValidHeaderSpecific(X,VEC_CLASSID,2);
    PetscValidHeaderSpecific(G,VEC_CLASSID,4);
    PetscCheckSameComm(tao,1,X,2);
    PetscCheckSameComm(tao,1,G,4);
    if (tao->ops->computeobjectiveandgradient) {
        ierr = PetscLogEventBegin(Tao_ObjGradientEval,tao,X,G,NULL);
        CHKERRQ(ierr);
        PetscStackPush("Tao user objective/gradient evaluation routine");
        ierr = (*tao->ops->computeobjectiveandgradient)(tao,X,f,G,tao->user_objgradP);
        CHKERRQ(ierr);
        PetscStackPop;
        if (tao->ops->computegradient == TaoDefaultComputeGradient) {
            /* Overwrite gradient with finite difference gradient */
            ierr = TaoDefaultComputeGradient(tao,X,G,tao->user_objgradP);
            CHKERRQ(ierr);
        }
        ierr = PetscLogEventEnd(Tao_ObjGradientEval,tao,X,G,NULL);
        CHKERRQ(ierr);
        tao->nfuncgrads++;
    } else if (tao->ops->computeobjective && tao->ops->computegradient) {
        ierr = PetscLogEventBegin(Tao_ObjectiveEval,tao,X,NULL,NULL);
        CHKERRQ(ierr);
        PetscStackPush("Tao user objective evaluation routine");
        ierr = (*tao->ops->computeobjective)(tao,X,f,tao->user_objP);
        CHKERRQ(ierr);
        PetscStackPop;
        ierr = PetscLogEventEnd(Tao_ObjectiveEval,tao,X,NULL,NULL);
        CHKERRQ(ierr);
        tao->nfuncs++;
        ierr = PetscLogEventBegin(Tao_GradientEval,tao,X,G,NULL);
        CHKERRQ(ierr);
        PetscStackPush("Tao user gradient evaluation routine");
        ierr = (*tao->ops->computegradient)(tao,X,G,tao->user_gradP);
        CHKERRQ(ierr);
        PetscStackPop;
        ierr = PetscLogEventEnd(Tao_GradientEval,tao,X,G,NULL);
        CHKERRQ(ierr);
        tao->ngrads++;
    } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"TaoSetObjectiveRoutine() or TaoSetGradientRoutine() not set");
    ierr = PetscInfo1(tao,"TAO Function evaluation: %14.12e\n",(double)(*f));
    CHKERRQ(ierr);
    PetscFunctionReturn(0);
}

PetscErrorCode MatSetUpMultiply_MPIDense(Mat mat)
{
  Mat_MPIDense   *mdn = (Mat_MPIDense*)mat->data;
  PetscErrorCode ierr;
  IS             from,to;
  Vec            gvec;

  PetscFunctionBegin;
  /* Create local vector that is used to scatter into */
  ierr = VecCreateSeq(PETSC_COMM_SELF,mat->cmap->N,&mdn->lvec);CHKERRQ(ierr);

  /* Create temporary index set for building scatter gather */
  ierr = ISCreateStride(PetscObjectComm((PetscObject)mat),mat->cmap->N,0,1,&from);CHKERRQ(ierr);
  ierr = ISCreateStride(PETSC_COMM_SELF,mat->cmap->N,0,1,&to);CHKERRQ(ierr);

  /* Create temporary global vector to generate scatter context */
  /* n    = mdn->cowners[mdn->rank+1] - mdn->cowners[mdn->rank]; */

  ierr = VecCreateMPIWithArray(PetscObjectComm((PetscObject)mat),1,mdn->nvec,mat->cmap->N,NULL,&gvec);CHKERRQ(ierr);

  /* Generate the scatter context */
  ierr = VecScatterCreate(gvec,from,mdn->lvec,to,&mdn->Mvctx);CHKERRQ(ierr);
  ierr = PetscLogObjectParent((PetscObject)mat,(PetscObject)mdn->Mvctx);CHKERRQ(ierr);
  ierr = PetscLogObjectParent((PetscObject)mat,(PetscObject)mdn->lvec);CHKERRQ(ierr);
  ierr = PetscLogObjectParent((PetscObject)mat,(PetscObject)from);CHKERRQ(ierr);
  ierr = PetscLogObjectParent((PetscObject)mat,(PetscObject)to);CHKERRQ(ierr);
  ierr = PetscLogObjectParent((PetscObject)mat,(PetscObject)gvec);CHKERRQ(ierr);

  ierr = ISDestroy(&to);CHKERRQ(ierr);
  ierr = ISDestroy(&from);CHKERRQ(ierr);
  ierr = VecDestroy(&gvec);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

PetscErrorCode MatSetUpMultiply_MPISBAIJ_2comm(Mat mat)
{
  Mat_MPISBAIJ       *baij = (Mat_MPISBAIJ*)mat->data;
  Mat_SeqBAIJ        *B = (Mat_SeqBAIJ*)(baij->B->data);  
  PetscErrorCode     ierr;
  PetscInt           i,j,*aj = B->j,ec = 0,*garray;
  PetscInt           bs = mat->rmap->bs,*stmp;
  IS                 from,to;
  Vec                gvec;
#if defined (PETSC_USE_CTABLE)
  PetscTable         gid1_lid1;
  PetscTablePosition tpos;
  PetscInt           gid,lid;
#else
  PetscInt           Nbs = baij->Nbs,*indices;
#endif  

  PetscFunctionBegin;
#if defined (PETSC_USE_CTABLE)
  /* use a table - Mark Adams */
  PetscTableCreate(B->mbs,baij->Nbs+1,&gid1_lid1); 
  for (i=0; i<B->mbs; i++) {
    for (j=0; j<B->ilen[i]; j++) {
      PetscInt data,gid1 = aj[B->i[i]+j] + 1;
      ierr = PetscTableFind(gid1_lid1,gid1,&data);CHKERRQ(ierr);
      if (!data) {
        /* one based table */ 
        ierr = PetscTableAdd(gid1_lid1,gid1,++ec,INSERT_VALUES);CHKERRQ(ierr); 
      }
    }
  } 
  /* form array of columns we need */
  ierr = PetscMalloc(ec*sizeof(PetscInt),&garray);CHKERRQ(ierr);
  ierr = PetscTableGetHeadPosition(gid1_lid1,&tpos);CHKERRQ(ierr); 
  while (tpos) {  
    ierr = PetscTableGetNext(gid1_lid1,&tpos,&gid,&lid);CHKERRQ(ierr); 
    gid--; lid--;
    garray[lid] = gid; 
  }
  ierr = PetscSortInt(ec,garray);CHKERRQ(ierr);
  ierr = PetscTableRemoveAll(gid1_lid1);CHKERRQ(ierr);
  for (i=0; i<ec; i++) {
    ierr = PetscTableAdd(gid1_lid1,garray[i]+1,i+1,INSERT_VALUES);CHKERRQ(ierr); 
  }
  /* compact out the extra columns in B */
  for (i=0; i<B->mbs; i++) {
    for (j=0; j<B->ilen[i]; j++) {
      PetscInt gid1 = aj[B->i[i] + j] + 1;
      ierr = PetscTableFind(gid1_lid1,gid1,&lid);CHKERRQ(ierr);
      lid --;
      aj[B->i[i]+j] = lid;
    }
  }
  B->nbs     = ec;
  baij->B->cmap->n = baij->B->cmap->N = ec*mat->rmap->bs;
  ierr = PetscLayoutSetUp((baij->B->cmap));CHKERRQ(ierr);
  ierr = PetscTableDestroy(&gid1_lid1);CHKERRQ(ierr);
#else
  /* For the first stab we make an array as long as the number of columns */
  /* mark those columns that are in baij->B */
  ierr = PetscMalloc(Nbs*sizeof(PetscInt),&indices);CHKERRQ(ierr);
  ierr = PetscMemzero(indices,Nbs*sizeof(PetscInt));CHKERRQ(ierr);
  for (i=0; i<B->mbs; i++) {
    for (j=0; j<B->ilen[i]; j++) {
      if (!indices[aj[B->i[i] + j]]) ec++; 
      indices[aj[B->i[i] + j] ] = 1;
    }
  }

  /* form array of columns we need */
  ierr = PetscMalloc(ec*sizeof(PetscInt),&garray);CHKERRQ(ierr);
  ec = 0;
  for (i=0; i<Nbs; i++) {
    if (indices[i]) {
      garray[ec++] = i;
    }
  }

  /* make indices now point into garray */
  for (i=0; i<ec; i++) {
    indices[garray[i]] = i;
  }

  /* compact out the extra columns in B */
  for (i=0; i<B->mbs; i++) {
    for (j=0; j<B->ilen[i]; j++) {
      aj[B->i[i] + j] = indices[aj[B->i[i] + j]];
    }
  }
  B->nbs       = ec;
  baij->B->cmap->n   = ec*mat->rmap->bs;
  ierr = PetscFree(indices);CHKERRQ(ierr);
#endif  
  
  /* create local vector that is used to scatter into */
  ierr = VecCreateSeq(PETSC_COMM_SELF,ec*bs,&baij->lvec);CHKERRQ(ierr);

  /* create two temporary index sets for building scatter-gather */
  ierr = ISCreateBlock(PETSC_COMM_SELF,bs,ec,garray,PETSC_COPY_VALUES,&from);CHKERRQ(ierr);   

//.........这里部分代码省略.........