impls/parms/parms.c

#define PETSCKSP_DLL

/*
   Provides an interface to pARMS.
   Requires pARMS 3.2 or later.
*/

#include <petsc/private/pcimpl.h> /*I "petscpc.h" I*/

#if defined(PETSC_USE_COMPLEX)
  #define DBL_CMPLX
#else
  #define DBL
#endif
#define USE_MPI
#define REAL double
#define HAS_BLAS
#define FORTRAN_UNDERSCORE
#include "parms_sys.h"
#undef FLOAT
#define FLOAT PetscScalar
#include <parms.h>

/*
   Private context (data structure) for the  preconditioner.
*/
typedef struct {
  parms_Map         map;
  parms_Mat         A;
  parms_PC          pc;
  PCPARMSGlobalType global;
  PCPARMSLocalType  local;
  PetscInt          levels, blocksize, maxdim, maxits, lfil[7];
  PetscBool         nonsymperm, meth[8];
  PetscReal         solvetol, indtol, droptol[7];
  PetscScalar      *lvec0, *lvec1;
} PC_PARMS;

static PetscErrorCode PCSetUp_PARMS(PC pc)
{
  Mat                pmat;
  PC_PARMS          *parms = (PC_PARMS *)pc->data;
  const PetscInt    *mapptr0;
  PetscInt           n, lsize, low, high, i, pos, ncols, length;
  int               *maptmp, *mapptr, *ia, *ja, *ja1, *im;
  PetscScalar       *aa, *aa1;
  const PetscInt    *cols;
  PetscInt           meth[8];
  const PetscScalar *values;
  MatInfo            matinfo;
  PetscMPIInt        rank, npro;

  PetscFunctionBegin;
  /* Get preconditioner matrix from PETSc and setup pARMS structs */
  PetscCall(PCGetOperators(pc, NULL, &pmat));
  PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)pmat), &npro));
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)pmat), &rank));

  PetscCall(MatGetSize(pmat, &n, NULL));
  PetscCall(PetscMalloc1(npro + 1, &mapptr));
  PetscCall(PetscMalloc1(n, &maptmp));
  PetscCall(MatGetOwnershipRanges(pmat, &mapptr0));
  low   = mapptr0[rank];
  high  = mapptr0[rank + 1];
  lsize = high - low;

  for (i = 0; i < npro + 1; i++) mapptr[i] = mapptr0[i] + 1;
  for (i = 0; i < n; i++) maptmp[i] = i + 1;

  /* if created, destroy the previous map */
  if (parms->map) {
    parms_MapFree(&parms->map);
    parms->map = NULL;
  }

  /* create pARMS map object */
  parms_MapCreateFromPtr(&parms->map, (int)n, maptmp, mapptr, PetscObjectComm((PetscObject)pmat), 1, NONINTERLACED);

  /* if created, destroy the previous pARMS matrix */
  if (parms->A) {
    parms_MatFree(&parms->A);
    parms->A = NULL;
  }

  /* create pARMS mat object */
  parms_MatCreate(&parms->A, parms->map);

  /* setup and copy csr data structure for pARMS */
  PetscCall(PetscMalloc1(lsize + 1, &ia));
  ia[0] = 1;
  PetscCall(MatGetInfo(pmat, MAT_LOCAL, &matinfo));
  length = matinfo.nz_used;
  PetscCall(PetscMalloc1(length, &ja));
  PetscCall(PetscMalloc1(length, &aa));

  for (i = low; i < high; i++) {
    pos = ia[i - low] - 1;
    PetscCall(MatGetRow(pmat, i, &ncols, &cols, &values));
    ia[i - low + 1] = ia[i - low] + ncols;

    if (ia[i - low + 1] >= length) {
      length += ncols;
      PetscCall(PetscMalloc1(length, &ja1));
      PetscCall(PetscArraycpy(ja1, ja, ia[i - low] - 1));
      PetscCall(PetscFree(ja));
      ja = ja1;
      PetscCall(PetscMalloc1(length, &aa1));
      PetscCall(PetscArraycpy(aa1, aa, ia[i - low] - 1));
      PetscCall(PetscFree(aa));
      aa = aa1;
    }
    PetscCall(PetscArraycpy(&ja[pos], cols, ncols));
    PetscCall(PetscArraycpy(&aa[pos], values, ncols));
    PetscCall(MatRestoreRow(pmat, i, &ncols, &cols, &values));
  }

  /* csr info is for local matrix so initialize im[] locally */
  PetscCall(PetscMalloc1(lsize, &im));
  PetscCall(PetscArraycpy(im, &maptmp[mapptr[rank] - 1], lsize));

  /* 1-based indexing */
  for (i = 0; i < ia[lsize] - 1; i++) ja[i] = ja[i] + 1;

  /* Now copy csr matrix to parms_mat object */
  parms_MatSetValues(parms->A, (int)lsize, im, ia, ja, aa, INSERT);

  /* free memory */
  PetscCall(PetscFree(maptmp));
  PetscCall(PetscFree(mapptr));
  PetscCall(PetscFree(aa));
  PetscCall(PetscFree(ja));
  PetscCall(PetscFree(ia));
  PetscCall(PetscFree(im));

  /* setup parms matrix */
  parms_MatSetup(parms->A);

  /* if created, destroy the previous pARMS pc */
  if (parms->pc) {
    parms_PCFree(&parms->pc);
    parms->pc = NULL;
  }

  /* Now create pARMS preconditioner object based on A */
  parms_PCCreate(&parms->pc, parms->A);

  /* Transfer options from PC to pARMS */
  switch (parms->global) {
  case 0:
    parms_PCSetType(parms->pc, PCRAS);
    break;
  case 1:
    parms_PCSetType(parms->pc, PCSCHUR);
    break;
  case 2:
    parms_PCSetType(parms->pc, PCBJ);
    break;
  }
  switch (parms->local) {
  case 0:
    parms_PCSetILUType(parms->pc, PCILU0);
    break;
  case 1:
    parms_PCSetILUType(parms->pc, PCILUK);
    break;
  case 2:
    parms_PCSetILUType(parms->pc, PCILUT);
    break;
  case 3:
    parms_PCSetILUType(parms->pc, PCARMS);
    break;
  }
  parms_PCSetInnerEps(parms->pc, parms->solvetol);
  parms_PCSetNlevels(parms->pc, parms->levels);
  parms_PCSetPermType(parms->pc, parms->nonsymperm ? 1 : 0);
  parms_PCSetBsize(parms->pc, parms->blocksize);
  parms_PCSetTolInd(parms->pc, parms->indtol);
  parms_PCSetInnerKSize(parms->pc, parms->maxdim);
  parms_PCSetInnerMaxits(parms->pc, parms->maxits);
  for (i = 0; i < 8; i++) meth[i] = parms->meth[i] ? 1 : 0;
  parms_PCSetPermScalOptions(parms->pc, &meth[0], 1);
  parms_PCSetPermScalOptions(parms->pc, &meth[4], 0);
  parms_PCSetFill(parms->pc, parms->lfil);
  parms_PCSetTol(parms->pc, parms->droptol);

  parms_PCSetup(parms->pc);

  /* Allocate two auxiliary vector of length lsize */
  if (parms->lvec0) PetscCall(PetscFree(parms->lvec0));
  PetscCall(PetscMalloc1(lsize, &parms->lvec0));
  if (parms->lvec1) PetscCall(PetscFree(parms->lvec1));
  PetscCall(PetscMalloc1(lsize, &parms->lvec1));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCView_PARMS(PC pc, PetscViewer viewer)
{
  PetscBool iascii;
  PC_PARMS *parms = (PC_PARMS *)pc->data;
  char     *str;
  double    fill_fact;

  PetscFunctionBegin;
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
  if (iascii) {
    parms_PCGetName(parms->pc, &str);
    PetscCall(PetscViewerASCIIPrintf(viewer, "  global preconditioner: %s\n", str));
    parms_PCILUGetName(parms->pc, &str);
    PetscCall(PetscViewerASCIIPrintf(viewer, "  local preconditioner: %s\n", str));
    parms_PCGetRatio(parms->pc, &fill_fact);
    PetscCall(PetscViewerASCIIPrintf(viewer, "  non-zero elements/original non-zero entries: %-4.2f\n", fill_fact));
    PetscCall(PetscViewerASCIIPrintf(viewer, "  Tolerance for local solve: %g\n", parms->solvetol));
    PetscCall(PetscViewerASCIIPrintf(viewer, "  Number of levels: %d\n", parms->levels));
    if (parms->nonsymperm) PetscCall(PetscViewerASCIIPrintf(viewer, "  Using nonsymmetric permutation\n"));
    PetscCall(PetscViewerASCIIPrintf(viewer, "  Block size: %d\n", parms->blocksize));
    PetscCall(PetscViewerASCIIPrintf(viewer, "  Tolerance for independent sets: %g\n", parms->indtol));
    PetscCall(PetscViewerASCIIPrintf(viewer, "  Inner Krylov dimension: %d\n", parms->maxdim));
    PetscCall(PetscViewerASCIIPrintf(viewer, "  Maximum number of inner iterations: %d\n", parms->maxits));
    if (parms->meth[0]) PetscCall(PetscViewerASCIIPrintf(viewer, "  Using nonsymmetric permutation for interlevel blocks\n"));
    if (parms->meth[1]) PetscCall(PetscViewerASCIIPrintf(viewer, "  Using column permutation for interlevel blocks\n"));
    if (parms->meth[2]) PetscCall(PetscViewerASCIIPrintf(viewer, "  Using row scaling for interlevel blocks\n"));
    if (parms->meth[3]) PetscCall(PetscViewerASCIIPrintf(viewer, "  Using column scaling for interlevel blocks\n"));
    if (parms->meth[4]) PetscCall(PetscViewerASCIIPrintf(viewer, "  Using nonsymmetric permutation for last level blocks\n"));
    if (parms->meth[5]) PetscCall(PetscViewerASCIIPrintf(viewer, "  Using column permutation for last level blocks\n"));
    if (parms->meth[6]) PetscCall(PetscViewerASCIIPrintf(viewer, "  Using row scaling for last level blocks\n"));
    if (parms->meth[7]) PetscCall(PetscViewerASCIIPrintf(viewer, "  Using column scaling for last level blocks\n"));
    PetscCall(PetscViewerASCIIPrintf(viewer, "  amount of fill-in for ilut, iluk and arms: %d\n", parms->lfil[0]));
    PetscCall(PetscViewerASCIIPrintf(viewer, "  amount of fill-in for schur: %d\n", parms->lfil[4]));
    PetscCall(PetscViewerASCIIPrintf(viewer, "  amount of fill-in for ILUT L and U: %d\n", parms->lfil[5]));
    PetscCall(PetscViewerASCIIPrintf(viewer, "  drop tolerance for L, U, L^{-1}F and EU^{-1}: %g\n", parms->droptol[0]));
    PetscCall(PetscViewerASCIIPrintf(viewer, "  drop tolerance for schur complement at each level: %g\n", parms->droptol[4]));
    PetscCall(PetscViewerASCIIPrintf(viewer, "  drop tolerance for ILUT in last level schur complement: %g\n", parms->droptol[5]));
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCDestroy_PARMS(PC pc)
{
  PC_PARMS *parms = (PC_PARMS *)pc->data;

  PetscFunctionBegin;
  if (parms->map) parms_MapFree(&parms->map);
  if (parms->A) parms_MatFree(&parms->A);
  if (parms->pc) parms_PCFree(&parms->pc);
  if (parms->lvec0) PetscCall(PetscFree(parms->lvec0));
  if (parms->lvec1) PetscCall(PetscFree(parms->lvec1));
  PetscCall(PetscFree(pc->data));

  PetscCall(PetscObjectChangeTypeName((PetscObject)pc, 0));
  PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCPARMSSetGlobal_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCPARMSSetLocal_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCPARMSSetSolveTolerances_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCPARMSSetSolveRestart_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCPARMSSetNonsymPerm_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCPARMSSetFill_C", NULL));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCSetFromOptions_PARMS(PC pc, PetscOptionItems *PetscOptionsObject)
{
  PC_PARMS         *parms = (PC_PARMS *)pc->data;
  PetscBool         flag;
  PCPARMSGlobalType global;
  PCPARMSLocalType  local;

  PetscFunctionBegin;
  PetscOptionsHeadBegin(PetscOptionsObject, "PARMS Options");
  PetscCall(PetscOptionsEnum("-pc_parms_global", "Global preconditioner", "PCPARMSSetGlobal", PCPARMSGlobalTypes, (PetscEnum)parms->global, (PetscEnum *)&global, &flag));
  if (flag) PetscCall(PCPARMSSetGlobal(pc, global));
  PetscCall(PetscOptionsEnum("-pc_parms_local", "Local preconditioner", "PCPARMSSetLocal", PCPARMSLocalTypes, (PetscEnum)parms->local, (PetscEnum *)&local, &flag));
  if (flag) PetscCall(PCPARMSSetLocal(pc, local));
  PetscCall(PetscOptionsReal("-pc_parms_solve_tol", "Tolerance for local solve", "PCPARMSSetSolveTolerances", parms->solvetol, &parms->solvetol, NULL));
  PetscCall(PetscOptionsInt("-pc_parms_levels", "Number of levels", "None", parms->levels, &parms->levels, NULL));
  PetscCall(PetscOptionsBool("-pc_parms_nonsymmetric_perm", "Use nonsymmetric permutation", "PCPARMSSetNonsymPerm", parms->nonsymperm, &parms->nonsymperm, NULL));
  PetscCall(PetscOptionsInt("-pc_parms_blocksize", "Block size", "None", parms->blocksize, &parms->blocksize, NULL));
  PetscCall(PetscOptionsReal("-pc_parms_ind_tol", "Tolerance for independent sets", "None", parms->indtol, &parms->indtol, NULL));
  PetscCall(PetscOptionsInt("-pc_parms_max_dim", "Inner Krylov dimension", "PCPARMSSetSolveRestart", parms->maxdim, &parms->maxdim, NULL));
  PetscCall(PetscOptionsInt("-pc_parms_max_it", "Maximum number of inner iterations", "PCPARMSSetSolveTolerances", parms->maxits, &parms->maxits, NULL));
  PetscCall(PetscOptionsBool("-pc_parms_inter_nonsymmetric_perm", "nonsymmetric permutation for interlevel blocks", "None", parms->meth[0], &parms->meth[0], NULL));
  PetscCall(PetscOptionsBool("-pc_parms_inter_column_perm", "column permutation for interlevel blocks", "None", parms->meth[1], &parms->meth[1], NULL));
  PetscCall(PetscOptionsBool("-pc_parms_inter_row_scaling", "row scaling for interlevel blocks", "None", parms->meth[2], &parms->meth[2], NULL));
  PetscCall(PetscOptionsBool("-pc_parms_inter_column_scaling", "column scaling for interlevel blocks", "None", parms->meth[3], &parms->meth[3], NULL));
  PetscCall(PetscOptionsBool("-pc_parms_last_nonsymmetric_perm", "nonsymmetric permutation for last level blocks", "None", parms->meth[4], &parms->meth[4], NULL));
  PetscCall(PetscOptionsBool("-pc_parms_last_column_perm", "column permutation for last level blocks", "None", parms->meth[5], &parms->meth[5], NULL));
  PetscCall(PetscOptionsBool("-pc_parms_last_row_scaling", "row scaling for last level blocks", "None", parms->meth[6], &parms->meth[6], NULL));
  PetscCall(PetscOptionsBool("-pc_parms_last_column_scaling", "column scaling for last level blocks", "None", parms->meth[7], &parms->meth[7], NULL));
  PetscCall(PetscOptionsInt("-pc_parms_lfil_ilu_arms", "amount of fill-in for ilut, iluk and arms", "PCPARMSSetFill", parms->lfil[0], &parms->lfil[0], &flag));
  if (flag) parms->lfil[1] = parms->lfil[2] = parms->lfil[3] = parms->lfil[0];
  PetscCall(PetscOptionsInt("-pc_parms_lfil_schur", "amount of fill-in for schur", "PCPARMSSetFill", parms->lfil[4], &parms->lfil[4], NULL));
  PetscCall(PetscOptionsInt("-pc_parms_lfil_ilut_L_U", "amount of fill-in for ILUT L and U", "PCPARMSSetFill", parms->lfil[5], &parms->lfil[5], &flag));
  if (flag) parms->lfil[6] = parms->lfil[5];
  PetscCall(PetscOptionsReal("-pc_parms_droptol_factors", "drop tolerance for L, U, L^{-1}F and EU^{-1}", "None", parms->droptol[0], &parms->droptol[0], NULL));
  PetscCall(PetscOptionsReal("-pc_parms_droptol_schur_compl", "drop tolerance for schur complement at each level", "None", parms->droptol[4], &parms->droptol[4], &flag));
  if (flag) parms->droptol[1] = parms->droptol[2] = parms->droptol[3] = parms->droptol[0];
  PetscCall(PetscOptionsReal("-pc_parms_droptol_last_schur", "drop tolerance for ILUT in last level schur complement", "None", parms->droptol[5], &parms->droptol[5], &flag));
  if (flag) parms->droptol[6] = parms->droptol[5];
  PetscOptionsHeadEnd();
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCApply_PARMS(PC pc, Vec b, Vec x)
{
  PC_PARMS          *parms = (PC_PARMS *)pc->data;
  const PetscScalar *b1;
  PetscScalar       *x1;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(b, &b1));
  PetscCall(VecGetArray(x, &x1));
  parms_VecPermAux((PetscScalar *)b1, parms->lvec0, parms->map);
  parms_PCApply(parms->pc, parms->lvec0, parms->lvec1);
  parms_VecInvPermAux(parms->lvec1, x1, parms->map);
  PetscCall(VecRestoreArrayRead(b, &b1));
  PetscCall(VecRestoreArray(x, &x1));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCPARMSSetGlobal_PARMS(PC pc, PCPARMSGlobalType type)
{
  PC_PARMS *parms = (PC_PARMS *)pc->data;

  PetscFunctionBegin;
  if (type != parms->global) {
    parms->global   = type;
    pc->setupcalled = 0;
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
   PCPARMSSetGlobal - Sets the global preconditioner to be used in `PCPARMS`.

   Collective

   Input Parameters:
+  pc - the preconditioner context
-  type - the global preconditioner type, one of
.vb
     PC_PARMS_GLOBAL_RAS   - Restricted additive Schwarz
     PC_PARMS_GLOBAL_SCHUR - Schur complement
     PC_PARMS_GLOBAL_BJ    - Block Jacobi
.ve

   Options Database Key:
.   -pc_parms_global [ras,schur,bj] - Sets global preconditioner

   Level: intermediate

   Note:
   See the pARMS function `parms_PCSetType()` for more information.

.seealso: `PCPARMS`, `PCPARMSSetLocal()`
@*/
PetscErrorCode PCPARMSSetGlobal(PC pc, PCPARMSGlobalType type)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(pc, PC_CLASSID, 1);
  PetscValidLogicalCollectiveEnum(pc, type, 2);
  PetscTryMethod(pc, "PCPARMSSetGlobal_C", (PC, PCPARMSGlobalType), (pc, type));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCPARMSSetLocal_PARMS(PC pc, PCPARMSLocalType type)
{
  PC_PARMS *parms = (PC_PARMS *)pc->data;

  PetscFunctionBegin;
  if (type != parms->local) {
    parms->local    = type;
    pc->setupcalled = 0;
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
   PCPARMSSetLocal - Sets the local preconditioner to be used in `PCPARMS`.

   Collective

   Input Parameters:
+  pc - the preconditioner context
-  type - the local preconditioner type, one of
.vb
     PC_PARMS_LOCAL_ILU0   - ILU0 preconditioner
     PC_PARMS_LOCAL_ILUK   - ILU(k) preconditioner
     PC_PARMS_LOCAL_ILUT   - ILUT preconditioner
     PC_PARMS_LOCAL_ARMS   - ARMS preconditioner
.ve

   Options Database Keys:
   -pc_parms_local [ilu0,iluk,ilut,arms] - Sets local preconditioner

   Level: intermediate

   Notes:
   For the ARMS preconditioner, one can use either the symmetric ARMS or the non-symmetric
   variant (ARMS-ddPQ) by setting the permutation type with PCPARMSSetNonsymPerm().

   See the pARMS function `parms_PCILUSetType()` for more information.

.seealso: `PCPARMS`, `PCPARMSSetGlobal()`, `PCPARMSSetNonsymPerm()`

@*/
PetscErrorCode PCPARMSSetLocal(PC pc, PCPARMSLocalType type)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(pc, PC_CLASSID, 1);
  PetscValidLogicalCollectiveEnum(pc, type, 2);
  PetscTryMethod(pc, "PCPARMSSetLocal_C", (PC, PCPARMSLocalType), (pc, type));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCPARMSSetSolveTolerances_PARMS(PC pc, PetscReal tol, PetscInt maxits)
{
  PC_PARMS *parms = (PC_PARMS *)pc->data;

  PetscFunctionBegin;
  if (tol != parms->solvetol) {
    parms->solvetol = tol;
    pc->setupcalled = 0;
  }
  if (maxits != parms->maxits) {
    parms->maxits   = maxits;
    pc->setupcalled = 0;
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
   PCPARMSSetSolveTolerances - Sets the convergence tolerance and the maximum iterations for the
   inner GMRES solver, when the Schur global preconditioner is used.

   Collective

   Input Parameters:
+  pc - the preconditioner context
.  tol - the convergence tolerance
-  maxits - the maximum number of iterations to use

   Options Database Keys:
+  -pc_parms_solve_tol - set the tolerance for local solve
-  -pc_parms_max_it - set the maximum number of inner iterations

   Level: intermediate

   Note:
   See the pARMS functions `parms_PCSetInnerEps()` and `parms_PCSetInnerMaxits()` for more information.

.seealso: `PCPARMS`, `PCPARMSSetSolveRestart()`
@*/
PetscErrorCode PCPARMSSetSolveTolerances(PC pc, PetscReal tol, PetscInt maxits)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(pc, PC_CLASSID, 1);
  PetscTryMethod(pc, "PCPARMSSetSolveTolerances_C", (PC, PetscReal, PetscInt), (pc, tol, maxits));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCPARMSSetSolveRestart_PARMS(PC pc, PetscInt restart)
{
  PC_PARMS *parms = (PC_PARMS *)pc->data;

  PetscFunctionBegin;
  if (restart != parms->maxdim) {
    parms->maxdim   = restart;
    pc->setupcalled = 0;
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
   PCPARMSSetSolveRestart - Sets the number of iterations at which the
   inner GMRES solver restarts.

   Collective

   Input Parameters:
+  pc - the preconditioner context
-  restart - maximum dimension of the Krylov subspace

   Options Database Key:
.  -pc_parms_max_dim - sets the inner Krylov dimension

   Level: intermediate

   Note:
   See the pARMS function parms_PCSetInnerKSize for more information.

.seealso: `PCPARMS`, `PCPARMSSetSolveTolerances()`
@*/
PetscErrorCode PCPARMSSetSolveRestart(PC pc, PetscInt restart)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(pc, PC_CLASSID, 1);
  PetscTryMethod(pc, "PCPARMSSetSolveRestart_C", (PC, PetscInt), (pc, restart));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCPARMSSetNonsymPerm_PARMS(PC pc, PetscBool nonsym)
{
  PC_PARMS *parms = (PC_PARMS *)pc->data;

  PetscFunctionBegin;
  if ((nonsym && !parms->nonsymperm) || (!nonsym && parms->nonsymperm)) {
    parms->nonsymperm = nonsym;
    pc->setupcalled   = 0;
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
   PCPARMSSetNonsymPerm - Sets the type of permutation for the ARMS preconditioner: the standard
   symmetric ARMS or the non-symmetric ARMS (ARMS-ddPQ).

   Collective

   Input Parameters:
+  pc - the preconditioner context
-  nonsym - `PETSC_TRUE` indicates the non-symmetric ARMS is used;
            `PETSC_FALSE` indicates the symmetric ARMS is used

   Options Database Key:
.  -pc_parms_nonsymmetric_perm - sets the use of nonsymmetric permutation

   Level: intermediate

   Note:
   See the pARMS function `parms_PCSetPermType()` for more information.

.seealso: `PCPARMS`
@*/
PetscErrorCode PCPARMSSetNonsymPerm(PC pc, PetscBool nonsym)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(pc, PC_CLASSID, 1);
  PetscTryMethod(pc, "PCPARMSSetNonsymPerm_C", (PC, PetscBool), (pc, nonsym));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCPARMSSetFill_PARMS(PC pc, PetscInt lfil0, PetscInt lfil1, PetscInt lfil2)
{
  PC_PARMS *parms = (PC_PARMS *)pc->data;

  PetscFunctionBegin;
  if (lfil0 != parms->lfil[0] || lfil0 != parms->lfil[1] || lfil0 != parms->lfil[2] || lfil0 != parms->lfil[3]) {
    parms->lfil[1] = parms->lfil[2] = parms->lfil[3] = parms->lfil[0] = lfil0;
    pc->setupcalled                                                   = 0;
  }
  if (lfil1 != parms->lfil[4]) {
    parms->lfil[4]  = lfil1;
    pc->setupcalled = 0;
  }
  if (lfil2 != parms->lfil[5] || lfil2 != parms->lfil[6]) {
    parms->lfil[5] = parms->lfil[6] = lfil2;
    pc->setupcalled                 = 0;
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
   PCPARMSSetFill - Sets the fill-in parameters for ILUT, ILUK and ARMS preconditioners.
   Consider the original matrix A = [B F; E C] and the approximate version
   M = [LB 0; E/UB I]*[UB LB\F; 0 S].

   Collective

   Input Parameters:
+  pc - the preconditioner context
.  fil0 - the level of fill-in kept in LB, UB, E/UB and LB\F
.  fil1 - the level of fill-in kept in S
-  fil2 - the level of fill-in kept in the L and U parts of the LU factorization of S

   Options Database Keys:
+  -pc_parms_lfil_ilu_arms - set the amount of fill-in for ilut, iluk and arms
.  -pc_parms_lfil_schur - set the amount of fill-in for schur
-  -pc_parms_lfil_ilut_L_U - set the amount of fill-in for ILUT L and U

   Level: intermediate

   Note:
   See the pARMS function `parms_PCSetFill()` for more information.

.seealso: `PCPARMS`
@*/
PetscErrorCode PCPARMSSetFill(PC pc, PetscInt lfil0, PetscInt lfil1, PetscInt lfil2)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(pc, PC_CLASSID, 1);
  PetscTryMethod(pc, "PCPARMSSetFill_C", (PC, PetscInt, PetscInt, PetscInt), (pc, lfil0, lfil1, lfil2));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*MC
   PCPARMS - Allows the use of the parallel Algebraic Recursive Multilevel Solvers
      available in the package pARMS

   Options Database Keys:
+  -pc_parms_global - one of ras, schur, bj
.  -pc_parms_local - one of ilu0, iluk, ilut, arms
.  -pc_parms_solve_tol - set the tolerance for local solve
.  -pc_parms_levels - set the number of levels
.  -pc_parms_nonsymmetric_perm - set the use of nonsymmetric permutation
.  -pc_parms_blocksize - set the block size
.  -pc_parms_ind_tol - set the tolerance for independent sets
.  -pc_parms_max_dim - set the inner krylov dimension
.  -pc_parms_max_it - set the maximum number of inner iterations
.  -pc_parms_inter_nonsymmetric_perm - set the use of nonsymmetric permutation for interlevel blocks
.  -pc_parms_inter_column_perm - set the use of column permutation for interlevel blocks
.  -pc_parms_inter_row_scaling - set the use of row scaling for interlevel blocks
.  -pc_parms_inter_column_scaling - set the use of column scaling for interlevel blocks
.  -pc_parms_last_nonsymmetric_perm - set the use of nonsymmetric permutation for last level blocks
.  -pc_parms_last_column_perm - set the use of column permutation for last level blocks
.  -pc_parms_last_row_scaling - set the use of row scaling for last level blocks
.  -pc_parms_last_column_scaling - set the use of column scaling for last level blocks
.  -pc_parms_lfil_ilu_arms - set the amount of fill-in for ilut, iluk and arms
.  -pc_parms_lfil_schur - set the amount of fill-in for schur
.  -pc_parms_lfil_ilut_L_U - set the amount of fill-in for ILUT L and U
.  -pc_parms_droptol_factors - set the drop tolerance for L, U, L^{-1}F and EU^{-1}
.  -pc_parms_droptol_schur_compl - set the drop tolerance for schur complement at each level
-  -pc_parms_droptol_last_schur - set the drop tolerance for ILUT in last level schur complement

   Note:
   Unless configured appropriately, this preconditioner performs an inexact solve
   as part of the preconditioner application. Therefore, it must be used in combination
   with flexible variants of iterative solvers, such as `KSPFGMRES` or `KSPGCR`.

   Level: intermediate

.seealso: `PCCreate()`, `PCSetType()`, `PCType`, `PC`, `PCMG`, `PCGAMG`, `PCHYPRE`, `PCPARMSSetGlobal()`,
          `PCPARMSSetLocal()`, `PCPARMSSetSolveTolerances()`, `PCPARMSSetSolveRestart()`, `PCPARMSSetNonsymPerm()`,
          `PCPARMSSetFill()`
M*/

PETSC_EXTERN PetscErrorCode PCCreate_PARMS(PC pc)
{
  PC_PARMS *parms;

  PetscFunctionBegin;
  PetscCall(PetscNew(&parms));

  parms->map        = 0;
  parms->A          = 0;
  parms->pc         = 0;
  parms->global     = PC_PARMS_GLOBAL_RAS;
  parms->local      = PC_PARMS_LOCAL_ARMS;
  parms->levels     = 10;
  parms->nonsymperm = PETSC_TRUE;
  parms->blocksize  = 250;
  parms->maxdim     = 0;
  parms->maxits     = 0;
  parms->meth[0]    = PETSC_FALSE;
  parms->meth[1]    = PETSC_FALSE;
  parms->meth[2]    = PETSC_FALSE;
  parms->meth[3]    = PETSC_FALSE;
  parms->meth[4]    = PETSC_FALSE;
  parms->meth[5]    = PETSC_FALSE;
  parms->meth[6]    = PETSC_FALSE;
  parms->meth[7]    = PETSC_FALSE;
  parms->solvetol   = 0.01;
  parms->indtol     = 0.4;
  parms->lfil[0] = parms->lfil[1] = parms->lfil[2] = parms->lfil[3] = 20;
  parms->lfil[4] = parms->lfil[5] = parms->lfil[6] = 20;
  parms->droptol[0] = parms->droptol[1] = parms->droptol[2] = parms->droptol[3] = 0.00001;
  parms->droptol[4]                                                             = 0.001;
  parms->droptol[5] = parms->droptol[6] = 0.001;

  pc->data                = parms;
  pc->ops->destroy        = PCDestroy_PARMS;
  pc->ops->setfromoptions = PCSetFromOptions_PARMS;
  pc->ops->setup          = PCSetUp_PARMS;
  pc->ops->apply          = PCApply_PARMS;
  pc->ops->view           = PCView_PARMS;

  PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCPARMSSetGlobal_C", PCPARMSSetGlobal_PARMS));
  PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCPARMSSetLocal_C", PCPARMSSetLocal_PARMS));
  PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCPARMSSetSolveTolerances_C", PCPARMSSetSolveTolerances_PARMS));
  PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCPARMSSetSolveRestart_C", PCPARMSSetSolveRestart_PARMS));
  PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCPARMSSetNonsymPerm_C", PCPARMSSetNonsymPerm_PARMS));
  PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCPARMSSetFill_C", PCPARMSSetFill_PARMS));
  PetscFunctionReturn(PETSC_SUCCESS);
}