Date: 2024-07-30T17:31:09+00:00

Actual source code: petscpctypes.h

      1: #pragma once

      3: /* SUBMANSEC = PC */

      5: /*S
      6:    PC - Abstract PETSc object that manages all preconditioners including direct solvers such as `PCLU`

      8:    Level: beginner

     10: .seealso: [](doc_linsolve), [](sec_pc), `PCCreate()`, `PCSetType()`, `PCType`
     11: S*/
     12: typedef struct _p_PC *PC;

     14: /*J
     15:    PCType - String with the name of a PETSc preconditioner

     17:    Level: beginner

     19:    Note:
     20:    `PCRegister()` is used to register preconditioners that are then accessible via `PCSetType()`

     22: .seealso: [](doc_linsolve), [](sec_pc), `PCSetType()`, `PC`, `PCCreate()`, `PCRegister()`, `PCSetFromOptions()`, `PCLU`, `PCJACOBI`, `PCBJACOBI`
     23: J*/
     24: typedef const char *PCType;
     25: #define PCNONE               "none"
     26: #define PCJACOBI             "jacobi"
     27: #define PCSOR                "sor"
     28: #define PCLU                 "lu"
     29: #define PCQR                 "qr"
     30: #define PCSHELL              "shell"
     31: #define PCAMGX               "amgx"
     32: #define PCBJACOBI            "bjacobi"
     33: #define PCMG                 "mg"
     34: #define PCEISENSTAT          "eisenstat"
     35: #define PCILU                "ilu"
     36: #define PCICC                "icc"
     37: #define PCASM                "asm"
     38: #define PCGASM               "gasm"
     39: #define PCKSP                "ksp"
     40: #define PCBJKOKKOS           "bjkokkos"
     41: #define PCCOMPOSITE          "composite"
     42: #define PCREDUNDANT          "redundant"
     43: #define PCSPAI               "spai"
     44: #define PCNN                 "nn"
     45: #define PCCHOLESKY           "cholesky"
     46: #define PCPBJACOBI           "pbjacobi"
     47: #define PCVPBJACOBI          "vpbjacobi"
     48: #define PCMAT                "mat"
     49: #define PCHYPRE              "hypre"
     50: #define PCPARMS              "parms"
     51: #define PCFIELDSPLIT         "fieldsplit"
     52: #define PCTFS                "tfs"
     53: #define PCML                 "ml"
     54: #define PCGALERKIN           "galerkin"
     55: #define PCEXOTIC             "exotic"
     56: #define PCCP                 "cp"
     57: #define PCBFBT               "bfbt"
     58: #define PCLSC                "lsc"
     59: #define PCPYTHON             "python"
     60: #define PCPFMG               "pfmg"
     61: #define PCSMG                "smg"
     62: #define PCSYSPFMG            "syspfmg"
     63: #define PCREDISTRIBUTE       "redistribute"
     64: #define PCSVD                "svd"
     65: #define PCGAMG               "gamg"
     66: #define PCCHOWILUVIENNACL    "chowiluviennacl"
     67: #define PCROWSCALINGVIENNACL "rowscalingviennacl"
     68: #define PCSAVIENNACL         "saviennacl"
     69: #define PCBDDC               "bddc"
     70: #define PCKACZMARZ           "kaczmarz"
     71: #define PCTELESCOPE          "telescope"
     72: #define PCPATCH              "patch"
     73: #define PCLMVM               "lmvm"
     74: #define PCHMG                "hmg"
     75: #define PCDEFLATION          "deflation"
     76: #define PCHPDDM              "hpddm"
     77: #define PCH2OPUS             "h2opus"
     78: #define PCMPI                "mpi"

     80: /*E
     81:     PCSide - If the preconditioner is to be applied to the left, right
     82:              or symmetrically around the operator.

     84:    Values:
     85: +  `PC_LEFT`      - applied after the operator is applied
     86: .  `PC_RIGHT`     - applied before the operator is applied
     87: -  `PC_SYMMETRIC` - a portion of the preconditioner is applied before the operator and the transpose of this portion is applied after the operator is applied.

     89:    Level: beginner

     91:    Note:
     92:    Certain `KSPType` support only a subset of `PCSide` values

     94: .seealso: [](sec_pc), `PC`, `KSPSetPCSide()`, `KSP`, `KSPType`
     95: E*/
     96: typedef enum {
     97:   PC_SIDE_DEFAULT = -1,
     98:   PC_LEFT,
     99:   PC_RIGHT,
    100:   PC_SYMMETRIC
    101: } PCSide;
    102: #define PC_SIDE_MAX (PC_SYMMETRIC + 1)

    104: /*E
    105:     PCRichardsonConvergedReason - reason a `PCApplyRichardson()` method terminated

    107:    Level: advanced

    109: .seealso: [](sec_pc), `KSPRICHARDSON`, `PC`, `PCApplyRichardson()`
    110: E*/
    111: typedef enum {
    112:   PCRICHARDSON_CONVERGED_RTOL = 2,
    113:   PCRICHARDSON_CONVERGED_ATOL = 3,
    114:   PCRICHARDSON_CONVERGED_ITS  = 4,
    115:   PCRICHARDSON_DIVERGED_DTOL  = -4
    116: } PCRichardsonConvergedReason;

    118: /*E
    119:     PCJacobiType - What elements of the matrix are used to form the Jacobi preconditioner

    121:    Values:
    122: +  `PC_JACOBI_DIAGONAL` - use the diagonal entry, if it is zero use one
    123: .  `PC_JACOBI_ROWL1`    - add sum of absolute values in row i, j != i, to diag_ii
    124: .  `PC_JACOBI_ROWMAX`   - use the maximum absolute value in the row
    125: -  `PC_JACOBI_ROWSUM`   - use the sum of the values in the row (not the absolute values)

    127:    Level: intermediate

    129: .seealso: [](sec_pc), `PCJACOBI`, `PC`
    130: E*/
    131: typedef enum {
    132:   PC_JACOBI_DIAGONAL,
    133:   PC_JACOBI_ROWL1,
    134:   PC_JACOBI_ROWMAX,
    135:   PC_JACOBI_ROWSUM
    136: } PCJacobiType;

    138: /*E
    139:     PCASMType - Type of additive Schwarz method to use

    141:    Values:
    142: +  `PC_ASM_BASIC`        - Symmetric version where residuals from the ghost points are used
    143:                            and computed values in ghost regions are added together.
    144:                            Classical standard additive Schwarz as introduced in {cite}`dryja1987additive`.
    145: .  `PC_ASM_RESTRICT`     - Residuals from ghost points are used but computed values in ghost
    146:                            region are discarded {cite}`cs99`. Default.
    147: .  `PC_ASM_INTERPOLATE`  - Residuals from ghost points are not used, computed values in ghost
    148:                            region are added back in.
    149: -  `PC_ASM_NONE`         - Residuals from ghost points are not used, computed ghost values are
    150:                            discarded. Not very good.

    152:    Level: beginner

    154: .seealso: [](sec_pc), `PC`, `PCASM`, `PCASMSetType()`, `PCGASMType`
    155: E*/
    156: typedef enum {
    157:   PC_ASM_BASIC       = 3,
    158:   PC_ASM_RESTRICT    = 1,
    159:   PC_ASM_INTERPOLATE = 2,
    160:   PC_ASM_NONE        = 0
    161: } PCASMType;

    163: /*E
    164:     PCGASMType - Type of generalized additive Schwarz method to use (differs from `PCASM` in allowing multiple processors per subdomain).

    166:    Values:
    167: +  `PC_GASM_BASIC`       - Symmetric version where the full from the outer subdomain is used, and the resulting correction is applied
    168:                            over the outer subdomains.  As a result, points in the overlap will receive the sum of the corrections
    169:                            from neighboring subdomains. Classical standard additive Schwarz {cite}`dryja1987additive`.
    170: .  `PC_GASM_RESTRICT`    - Residual from the outer subdomain is used but the correction is restricted to the inner subdomain only
    171:                            (i.e., zeroed out over the overlap portion of the outer subdomain before being applied).  As a result,
    172:                            each point will receive a correction only from the unique inner subdomain containing it (nonoverlapping covering
    173:                            assumption) {cite}`cs99`. Default.
    174: .  `PC_GASM_INTERPOLATE` - Residual is zeroed out over the overlap portion of the outer subdomain, but the resulting correction is
    175:                            applied over the outer subdomain. As a result, points in the overlap will receive the sum of the corrections
    176:                            from neighboring subdomains.
    177: -  `PC_GASM_NONE`        - Residuals and corrections are zeroed out outside the local subdomains. Not very good.

    179:    Level: beginner

    181:    Note:
    182:    Each subdomain has nested inner and outer parts.  The inner subdomains are assumed to form a non-overlapping covering of the computational
    183:    domain, while the outer subdomains contain the inner subdomains and overlap with each other.  This preconditioner will compute
    184:    a subdomain correction over each *outer* subdomain from a residual computed there, but its different variants will differ in
    185:    (a) how the outer subdomain residual is computed, and (b) how the outer subdomain correction is computed.

    187:    Developer Note:
    188:    Perhaps better to remove this since it matches `PCASMType`

    190: .seealso: [](sec_pc), `PCGASM`, `PCASM`, `PC`, `PCGASMSetType()`, `PCASMType`
    191: E*/
    192: typedef enum {
    193:   PC_GASM_BASIC       = 3,
    194:   PC_GASM_RESTRICT    = 1,
    195:   PC_GASM_INTERPOLATE = 2,
    196:   PC_GASM_NONE        = 0
    197: } PCGASMType;

    199: /*E
    200:     PCCompositeType - Determines how two or more preconditioner are composed with the `PCType` of `PCCOMPOSITE`

    202:   Values:
    203: +  `PC_COMPOSITE_ADDITIVE`                 - results from application of all preconditioners are added together
    204: .  `PC_COMPOSITE_MULTIPLICATIVE`           - preconditioners are applied sequentially to the residual freshly
    205:                                              computed after the previous preconditioner application
    206: .  `PC_COMPOSITE_SYMMETRIC_MULTIPLICATIVE` - preconditioners are applied sequentially to the residual freshly
    207:                                              computed from first preconditioner to last and then back (Use only for symmetric matrices and preconditioners)
    208: .  `PC_COMPOSITE_SPECIAL`                  - This is very special for a matrix of the form $ \alpha I + R + S$
    209:                                              where the first preconditioner is built from $\alpha I + S$ and second from $\alpha I + R$
    210: .  `PC_COMPOSITE_SCHUR`                    - composes the Schur complement of the matrix from two blocks, see `PCFIELDSPLIT`
    211: -  `PC_COMPOSITE_GKB`                      - the generalized Golub-Kahan bidiagonalization preconditioner, see `PCFIELDSPLIT`

    213:    Level: beginner

    215: .seealso: [](sec_pc), `PCCOMPOSITE`, `PCFIELDSPLIT`, `PC`, `PCCompositeSetType()`, `SNESCompositeType`, `PCCompositeSpecialSetAlpha()`
    216: E*/
    217: typedef enum {
    218:   PC_COMPOSITE_ADDITIVE,
    219:   PC_COMPOSITE_MULTIPLICATIVE,
    220:   PC_COMPOSITE_SYMMETRIC_MULTIPLICATIVE,
    221:   PC_COMPOSITE_SPECIAL,
    222:   PC_COMPOSITE_SCHUR,
    223:   PC_COMPOSITE_GKB
    224: } PCCompositeType;

    226: /*E
    227:     PCFieldSplitSchurPreType - Determines how to precondition a Schur complement

    229:     Values:
    230: +  `PC_FIELDSPLIT_SCHUR_PRE_SELF`  - the preconditioner for the Schur complement is generated from the symbolic representation of the Schur complement matrix.
    231:                                      The only preconditioners that currently work with this symbolic representation matrix object are `PCLSC` and `PCHPDDM`
    232: .  `PC_FIELDSPLIT_SCHUR_PRE_SELFP` - the preconditioning for the Schur complement is generated from an explicitly-assembled approximation $Sp = A11 - A10 diag(A00)^{-1} A01$.
    233:                                      This is only a good preconditioner when $diag(A00)$ is a good preconditioner for $A00$. Optionally, $A00$ can be
    234:                                      lumped before extracting the diagonal using the additional option `-fieldsplit_1_mat_schur_complement_ainv_type lump`
    235: .  `PC_FIELDSPLIT_SCHUR_PRE_A11`   - the preconditioner for the Schur complement is generated from $A11$, not the Schur complement matrix
    236: .  `PC_FIELDSPLIT_SCHUR_PRE_USER`  - the preconditioner for the Schur complement is generated from the user provided matrix (pre argument
    237:                                      to this function).
    238: -  `PC_FIELDSPLIT_SCHUR_PRE_FULL`  - the preconditioner for the Schur complement is generated from the exact Schur complement matrix representation
    239:                                      computed internally by `PCFIELDSPLIT` (this is expensive) useful mostly as a test that the Schur complement approach can work for your problem

    241:     Level: intermediate

    243: .seealso: [](sec_pc), `PCFIELDSPLIT`, `PCFieldSplitSetSchurPre()`, `PC`
    244: E*/
    245: typedef enum {
    246:   PC_FIELDSPLIT_SCHUR_PRE_SELF,
    247:   PC_FIELDSPLIT_SCHUR_PRE_SELFP,
    248:   PC_FIELDSPLIT_SCHUR_PRE_A11,
    249:   PC_FIELDSPLIT_SCHUR_PRE_USER,
    250:   PC_FIELDSPLIT_SCHUR_PRE_FULL
    251: } PCFieldSplitSchurPreType;

    253: /*E
    254:     PCFieldSplitSchurFactType - determines which off-diagonal parts of the approximate block factorization to use

    256:     Values:
    257: +   `PC_FIELDSPLIT_SCHUR_FACT_DIAG`  - the preconditioner is solving `D`
    258: .   `PC_FIELDSPLIT_SCHUR_FACT_LOWER` - the preconditioner is solving `L D`
    259: .   `PC_FIELDSPLIT_SCHUR_FACT_UPPER` - the preconditioner is solving `D U`
    260: -   `PC_FIELDSPLIT_SCHUR_FACT_FULL`  - the preconditioner is solving `L(D U)`

    262:     where the matrix is factorized as
    263: .vb
    264:    (A   B)  = (1       0) (A   0) (1  Ainv*B)  = L D U
    265:    (C   E)    (C*Ainv  1) (0   S) (0       1)
    266: .ve

    268:     Level: intermediate

    270: .seealso: [](sec_pc), `PCFIELDSPLIT`, `PCFieldSplitSetSchurFactType()`, `PC`
    271: E*/
    272: typedef enum {
    273:   PC_FIELDSPLIT_SCHUR_FACT_DIAG,
    274:   PC_FIELDSPLIT_SCHUR_FACT_LOWER,
    275:   PC_FIELDSPLIT_SCHUR_FACT_UPPER,
    276:   PC_FIELDSPLIT_SCHUR_FACT_FULL
    277: } PCFieldSplitSchurFactType;

    279: /*E
    280:     PCPARMSGlobalType - Determines the global preconditioner method in `PCPARMS`

    282:     Level: intermediate

    284: .seealso: [](sec_pc), `PCPARMS`, `PCPARMSSetGlobal()`, `PC`
    285: E*/
    286: typedef enum {
    287:   PC_PARMS_GLOBAL_RAS,
    288:   PC_PARMS_GLOBAL_SCHUR,
    289:   PC_PARMS_GLOBAL_BJ
    290: } PCPARMSGlobalType;

    292: /*E
    293:     PCPARMSLocalType - Determines the local preconditioner method in `PCPARMS`

    295:     Level: intermediate

    297: .seealso: [](sec_pc), `PCPARMS`, `PCPARMSSetLocal()`, `PC`
    298: E*/
    299: typedef enum {
    300:   PC_PARMS_LOCAL_ILU0,
    301:   PC_PARMS_LOCAL_ILUK,
    302:   PC_PARMS_LOCAL_ILUT,
    303:   PC_PARMS_LOCAL_ARMS
    304: } PCPARMSLocalType;

    306: /*J
    307:     PCGAMGType - type of generalized algebraic multigrid `PCGAMG` method

    309:    Values:
    310: +   `PCGAMGAGG`       - (the default) smoothed aggregation algorithm, robust, very well tested
    311: .   `PCGAMGGEO`       - geometric coarsening, uses mesh generator to produce coarser meshes, limited to triangles, not supported, reference implementation (2D)
    312: -   `PCGAMGCLASSICAL` - classical algebraic multigrid preconditioner, incomplete, not supported, reference implementation

    314:      Level: intermediate

    316: .seealso: [](sec_pc), `PCGAMG`, `PCMG`, `PC`, `PCSetType()`, `PCGAMGSetThreshold()`, `PCGAMGSetThreshold()`, `PCGAMGSetReuseInterpolation()`
    317: J*/
    318: typedef const char *PCGAMGType;
    319: #define PCGAMGAGG       "agg"
    320: #define PCGAMGGEO       "geo"
    321: #define PCGAMGCLASSICAL "classical"

    323: typedef const char *PCGAMGClassicalType;
    324: #define PCGAMGCLASSICALDIRECT   "direct"
    325: #define PCGAMGCLASSICALSTANDARD "standard"

    327: /*E
    328:    PCMGType - Determines the type of multigrid method that is run.

    330:    Values:
    331: +  `PC_MG_MULTIPLICATIVE` (default) - traditional V or W cycle as determined by `PCMGSetCycleType()`
    332: .  `PC_MG_ADDITIVE`                 - the additive multigrid preconditioner where all levels are
    333:                                       smoothed before updating the residual. This only uses the
    334:                                       down smoother, in the preconditioner the upper smoother is ignored
    335: .  `PC_MG_FULL`                     - same as multiplicative except one also performs grid sequencing,
    336:                                       that is starts on the coarsest grid, performs a cycle, interpolates
    337:                                       to the next, performs a cycle etc. This is much like the F-cycle presented in "Multigrid" by Trottenberg, Oosterlee, Schuller page 49, but that
    338:                                       algorithm supports smoothing on before the restriction on each level in the initial restriction to the coarsest stage. In addition that algorithm
    339:                                       calls the V-cycle only on the coarser level and has a post-smoother instead.
    340: -  `PC_MG_KASKADE`                  - like full multigrid except one never goes back to a coarser level from a finer

    342:    Level: beginner

    344: .seealso: [](sec_pc), `PCMG`, `PC`, `PCMGSetType()`, `PCMGSetCycleType()`, `PCMGSetCycleTypeOnLevel()`
    345: E*/
    346: typedef enum {
    347:   PC_MG_MULTIPLICATIVE,
    348:   PC_MG_ADDITIVE,
    349:   PC_MG_FULL,
    350:   PC_MG_KASKADE
    351: } PCMGType;
    352: #define PC_MG_CASCADE PC_MG_KASKADE;

    354: /*E
    355:    PCMGCycleType - Use V-cycle or W-cycle

    357:    Values:
    358: +  `PC_MG_V_CYCLE` - use the V cycle
    359: -  `PC_MG_W_CYCLE` - use the W cycle

    361:    Level: beginner

    363: .seealso: [](sec_pc), `PCMG`, `PC`, `PCMGSetCycleType()`
    364: E*/
    365: typedef enum {
    366:   PC_MG_CYCLE_V = 1,
    367:   PC_MG_CYCLE_W = 2
    368: } PCMGCycleType;

    370: /*E
    371:     PCMGalerkinType - Determines if the coarse grid operators are computed via the Galerkin process

    373:    Values:
    374: +  `PC_MG_GALERKIN_PMAT` - computes the pmat (matrix from which the preconditioner is built) via the Galerkin process from the finest grid
    375: .  `PC_MG_GALERKIN_MAT` -  computes the mat (matrix used to apply the operator) via the Galerkin process from the finest grid
    376: .  `PC_MG_GALERKIN_BOTH` - computes both the mat and pmat via the Galerkin process (if pmat == mat the construction is only done once
    377: -  `PC_MG_GALERKIN_NONE` - neither operator is computed via the Galerkin process, the user must provide the operator

    379:    Level: beginner

    381:    Note:
    382:    Users should never set `PC_MG_GALERKIN_EXTERNAL`, it is used by `PCHYPRE` and `PCML`

    384: .seealso: [](sec_pc), `PCMG`, `PC`, `PCMGSetCycleType()`
    385: E*/
    386: typedef enum {
    387:   PC_MG_GALERKIN_BOTH,
    388:   PC_MG_GALERKIN_PMAT,
    389:   PC_MG_GALERKIN_MAT,
    390:   PC_MG_GALERKIN_NONE,
    391:   PC_MG_GALERKIN_EXTERNAL
    392: } PCMGGalerkinType;

    394: /*E
    395:     PCExoticType - Face based or wirebasket based coarse grid space

    397:    Level: beginner

    399: .seealso: [](sec_pc), `PCExoticSetType()`, `PCEXOTIC`
    400: E*/
    401: typedef enum {
    402:   PC_EXOTIC_FACE,
    403:   PC_EXOTIC_WIREBASKET
    404: } PCExoticType;

    406: /*E
    407:    PCBDDCInterfaceExtType - Defines how interface balancing is extended into the interior of subdomains.

    409:    Values:
    410: +  `PC_BDDC_INTERFACE_EXT_DIRICHLET` - solves Dirichlet interior problem; this is the standard BDDC algorithm
    411: -  `PC_BDDC_INTERFACE_EXT_LUMP`      - skips interior solve; sometimes called M_1 and associated with "lumped FETI-DP"

    413:    Level: intermediate

    415: .seealso: [](sec_pc), `PCBDDC`, `PC`
    416: E*/
    417: typedef enum {
    418:   PC_BDDC_INTERFACE_EXT_DIRICHLET,
    419:   PC_BDDC_INTERFACE_EXT_LUMP
    420: } PCBDDCInterfaceExtType;

    422: /*E
    423:   PCMGCoarseSpaceType - Function space for coarse space for adaptive interpolation

    425:   Level: beginner

    427: .seealso: [](sec_pc), `PCMGSetAdaptCoarseSpaceType()`, `PCMG`, `PC`
    428: E*/
    429: typedef enum {
    430:   PCMG_ADAPT_NONE,
    431:   PCMG_ADAPT_POLYNOMIAL,
    432:   PCMG_ADAPT_HARMONIC,
    433:   PCMG_ADAPT_EIGENVECTOR,
    434:   PCMG_ADAPT_GENERALIZED_EIGENVECTOR,
    435:   PCMG_ADAPT_GDSW
    436: } PCMGCoarseSpaceType;

    438: /*E
    439:     PCPatchConstructType - The algorithm used to construct patches for the `PCPATCH` preconditioner

    441:    Level: beginner

    443: .seealso: [](sec_pc), `PCPatchSetConstructType()`, `PCPATCH`, `PC`
    444: E*/
    445: typedef enum {
    446:   PC_PATCH_STAR,
    447:   PC_PATCH_VANKA,
    448:   PC_PATCH_PARDECOMP,
    449:   PC_PATCH_USER,
    450:   PC_PATCH_PYTHON
    451: } PCPatchConstructType;

    453: /*E
    454:     PCDeflationSpaceType - Type of deflation

    456:     Values:
    457: +   `PC_DEFLATION_SPACE_HAAR`        - directly assembled based on Haar (db2) wavelet with overflowed filter cuted-off
    458: .   `PC_DEFLATION_SPACE_DB2`         - `MATCOMPOSITE` of 1-lvl matices based on db2 (2 coefficient Daubechies / Haar wavelet)
    459: .   `PC_DEFLATION_SPACE_DB4`         - same as above, but with db4 (4 coefficient Daubechies)
    460: .   `PC_DEFLATION_SPACE_DB8`         - same as above, but with db8 (8 coefficient Daubechies)
    461: .   `PC_DEFLATION_SPACE_DB16`        - same as above, but with db16 (16 coefficient Daubechies)
    462: .   `PC_DEFLATION_SPACE_BIORTH22`    - same as above, but with biorthogonal 2.2 (6 coefficients)
    463: .   `PC_DEFLATION_SPACE_MEYER`       - same as above, but with Meyer/FIR (62 coefficients)
    464: .   `PC_DEFLATION_SPACE_AGGREGATION` - aggregates local indices (given by operator matrix distribution) into a subdomain
    465: -   `PC_DEFLATION_SPACE_USER`        - indicates space set by user

    467:     Level: intermediate

    469:     Note:
    470:     Wavelet-based space (except Haar) can be used in multilevel deflation.

    472: .seealso: [](sec_pc), `PCDeflationSetSpaceToCompute()`, `PCDEFLATION`, `PC`
    473: E*/
    474: typedef enum {
    475:   PC_DEFLATION_SPACE_HAAR,
    476:   PC_DEFLATION_SPACE_DB2,
    477:   PC_DEFLATION_SPACE_DB4,
    478:   PC_DEFLATION_SPACE_DB8,
    479:   PC_DEFLATION_SPACE_DB16,
    480:   PC_DEFLATION_SPACE_BIORTH22,
    481:   PC_DEFLATION_SPACE_MEYER,
    482:   PC_DEFLATION_SPACE_AGGREGATION,
    483:   PC_DEFLATION_SPACE_USER
    484: } PCDeflationSpaceType;

    486: /*E
    487:     PCHPDDMCoarseCorrectionType - Type of coarse correction used by `PCHPDDM`

    489:     Values:
    490: +   `PC_HPDDM_COARSE_CORRECTION_DEFLATED` (default) - eq. (1) in `PCHPDDMShellApply()`
    491: .   `PC_HPDDM_COARSE_CORRECTION_ADDITIVE`           - eq. (2)
    492: .   `PC_HPDDM_COARSE_CORRECTION_BALANCED`           - eq. (3)
    493: -   `PC_HPDDM_COARSE_CORRECTION_NONE`               - no coarse correction (mostly useful for debugging)

    495:     Level: intermediate

    497: .seealso: [](sec_pc), `PCHPDDM`, `PC`, `PCSetType()`, `PCHPDDMShellApply()`
    498: E*/
    499: typedef enum {
    500:   PC_HPDDM_COARSE_CORRECTION_DEFLATED,
    501:   PC_HPDDM_COARSE_CORRECTION_ADDITIVE,
    502:   PC_HPDDM_COARSE_CORRECTION_BALANCED,
    503:   PC_HPDDM_COARSE_CORRECTION_NONE
    504: } PCHPDDMCoarseCorrectionType;

    506: /*E
    507:     PCHPDDMSchurPreType - Type of `PCHPDDM` preconditioner for a `MATSCHURCOMPLEMENT` generated by `PCFIELDSPLIT` with `PCFieldSplitSchurPreType` set to `PC_FIELDSPLIT_SCHUR_PRE_SELF`

    509:     Values:
    510: +   `PC_HPDDM_SCHUR_PRE_LEAST_SQUARES` (default) - only with a near-zero A11 block and A10 = A01^T; a preconditioner for solving A01^T A00^-1 A01 x = b is built by approximating the Schur complement with (inv(sqrt(diag(A00))) A01)^T (inv(sqrt(diag(A00))) A01) and by considering the associated linear least squares problem
    511: -   `PC_HPDDM_SCHUR_PRE_GENEO` - only with A10 = A01^T, `PCHPDDMSetAuxiliaryMat()` called on the `PC` of the A00 block, and if A11 is nonzero, then `PCHPDDMSetAuxiliaryMat()` must be called on the associated `PC` as well (it is built automatically for the user otherwise); the Schur complement `PC` is set internally to `PCKSP`, with the prefix `-fieldsplit_1_pc_hpddm_`; the operator associated to the `PC` is spectrally equivalent to the original Schur complement

    513:     Level: advanced

    515: .seealso: [](sec_pc), `PCHPDDM`, `PC`, `PCFIELDSPLIT`, `PC_FIELDSPLIT_SCHUR_PRE_SELF`, `PCFieldSplitSetSchurPre()`, `PCHPDDMSetAuxiliaryMat()`
    516: E*/
    517: typedef enum {
    518:   PC_HPDDM_SCHUR_PRE_LEAST_SQUARES,
    519:   PC_HPDDM_SCHUR_PRE_GENEO,
    520: } PCHPDDMSchurPreType;

    522: /*E
    523:     PCFailedReason - indicates type of `PC` failure

    525:     Level: beginner

    527: .seealso: [](sec_pc), `PC`
    528: E*/
    529: typedef enum {
    530:   PC_SETUP_ERROR = -1,
    531:   PC_NOERROR,
    532:   PC_FACTOR_STRUCT_ZEROPIVOT,
    533:   PC_FACTOR_NUMERIC_ZEROPIVOT,
    534:   PC_FACTOR_OUTMEMORY,
    535:   PC_FACTOR_OTHER,
    536:   PC_INCONSISTENT_RHS,
    537:   PC_SUBPC_ERROR
    538: } PCFailedReason;

    540: /*E
    541:     PCGAMGLayoutType - Layout for reduced grids

    543:     Level: intermediate

    545: .seealso: [](sec_pc), `PCGAMG`, `PC`, `PCGAMGSetCoarseGridLayoutType()`
    546: E*/
    547: typedef enum {
    548:   PCGAMG_LAYOUT_COMPACT,
    549:   PCGAMG_LAYOUT_SPREAD
    550: } PCGAMGLayoutType;