1: #pragma once

  3: /* SUBMANSEC = IS */

  5: /*S
  6:    IS - Abstract PETSc object used for efficient indexing into vector and matrices

  8:    Level: beginner

 10: .seealso: `ISType`, `ISCreateGeneral()`, `ISCreateBlock()`, `ISCreateStride()`, `ISGetIndices()`, `ISDestroy()`
 11: S*/
 12: typedef struct _p_IS *IS;

 14: /*S
 15:    ISLocalToGlobalMapping - mappings from a
 16:    local ordering (on individual MPI processes) of 0 to n-1 to a global PETSc ordering (across collections of MPI processes)
 17:    used by a vector or matrix.

 19:    Level: intermediate

 21:    Note:
 22:    Mapping from local to global is scalable; but global
 23:    to local may not be if the range of global values represented locally
 24:    is very large. `ISLocalToGlobalMappingType` provides alternative ways of efficiently applying `ISGlobalToLocalMappingApply()

 26:    Developer Note:
 27:    `ISLocalToGlobalMapping` is actually a private object; it is included
 28:    here for the inline function `ISLocalToGlobalMappingApply()` to allow it to be inlined since
 29:    it is used so often.

 31: .seealso: `ISLocalToGlobalMappingCreate()`, `ISLocalToGlobalMappingApply()`, `ISLocalToGlobalMappingDestroy()`, `ISGlobalToLocalMappingApply()`
 32: S*/
 33: typedef struct _p_ISLocalToGlobalMapping *ISLocalToGlobalMapping;

 35: /*S
 36:    ISColoring - sets of `IS`s that define a coloring of something, such as a graph defined by a sparse matrix

 38:    Level: intermediate

 40:    Notes:
 41:    One should not access the *is records below directly because they may not yet
 42:    have been created. One should use `ISColoringGetIS()` to make sure they are
 43:    created when needed.

 45:    When the coloring type is `IS_COLORING_LOCAL` the coloring is in the local ordering of the unknowns.
 46:    That is the matching the local (ghosted) vector; a local to global mapping must be applied to map
 47:    them to the global ordering.

 49:    Developer Note:
 50:    This is not a `PetscObject`

 52: .seealso: `IS`, `MatColoringCreate()`, `MatColoring`, `ISColoringCreate()`, `ISColoringGetIS()`, `ISColoringView()`
 53: S*/
 54: typedef struct _n_ISColoring *ISColoring;

 56: /*S
 57:    PetscLayout - defines layout of vectors and matrices (that is the "global" numbering of vector and matrix entries) across MPI processes (which rows are owned by which processes)

 59:    Level: developer

 61:    Notes:
 62:    PETSc vectors (`Vec`) have a global number associated with each vector entry. The first MPI process that shares the vector owns the first `n0` entries of the vector,
 63:    the second MPI process the next `n1` entries, etc. A `PetscLayout` is a way of managing this information, for example the number of locally owned entries is provided
 64:    by `PetscLayoutGetLocalSize()` and the range of indices for a given MPI process is provided by `PetscLayoutGetRange()`.

 66:    Each PETSc `Vec` contains a `PetscLayout` object which can be obtained with `VecGetLayout()`. For convenience `Vec` provides an API to access the layout information directly,
 67:    for example with `VecGetLocalSize()` and `VecGetOwnershipRange()`.

 69:    Similarly PETSc matrices have layouts, these are discussed in [](ch_matrices).

 71: .seealso: `PetscLayoutCreate()`, `PetscLayoutDestroy()`, `PetscLayoutGetRange()`, `PetscLayoutGetLocalSize()`, `PetscLayoutGetSize()`,
 72:           `PetscLayoutGetBlockSize()`, `PetscLayoutGetRanges()`, `PetscLayoutFindOwner()`,  `PetscLayoutFindOwnerIndex()`,
 73:           `VecGetLayout()`, `VecGetLocalSize()`, `VecGetOwnershipRange()`
 74: S*/
 75: typedef struct _n_PetscLayout *PetscLayout;