1 #pragma once 2 3 /* MANSEC = Vec */ 4 /* SUBMANSEC = IS */ 5 6 /*S 7 IS - Abstract PETSc object used for efficient indexing into vector and matrices 8 9 Level: beginner 10 11 .seealso: `ISType`, `ISCreateGeneral()`, `ISCreateBlock()`, `ISCreateStride()`, `ISGetIndices()`, `ISDestroy()` 12 S*/ 13 typedef struct _p_IS *IS; 14 15 /*S 16 ISLocalToGlobalMapping - mappings from a 17 local ordering (on individual MPI processes) of 0 to n-1 to a global PETSc ordering (across collections of MPI processes) 18 used by a vector or matrix. 19 20 Level: intermediate 21 22 Note: 23 Mapping from local to global is scalable; but global 24 to local may not be if the range of global values represented locally 25 is very large. `ISLocalToGlobalMappingType` provides alternative ways of efficiently applying `ISGlobalToLocalMappingApply() 26 27 Developer Note: 28 `ISLocalToGlobalMapping` is actually a private object; it is included 29 here for the inline function `ISLocalToGlobalMappingApply()` to allow it to be inlined since 30 it is used so often. 31 32 .seealso: `ISLocalToGlobalMappingCreate()`, `ISLocalToGlobalMappingApply()`, `ISLocalToGlobalMappingDestroy()`, `ISGlobalToLocalMappingApply()` 33 S*/ 34 typedef struct _p_ISLocalToGlobalMapping *ISLocalToGlobalMapping; 35 36 /*S 37 ISColoring - sets of `IS`s that define a coloring of something, such as a graph defined by a sparse matrix 38 39 Level: intermediate 40 41 Notes: 42 One should not access the *is records below directly because they may not yet 43 have been created. One should use `ISColoringGetIS()` to make sure they are 44 created when needed. 45 46 When the coloring type is `IS_COLORING_LOCAL` the coloring is in the local ordering of the unknowns. 47 That is the matching the local (ghosted) vector; a local to global mapping must be applied to map 48 them to the global ordering. 49 50 Developer Note: 51 This is not a `PetscObject` 52 53 .seealso: `IS`, `MatColoringCreate()`, `MatColoring`, `ISColoringCreate()`, `ISColoringGetIS()`, `ISColoringView()` 54 S*/ 55 typedef struct _n_ISColoring *ISColoring; 56 57 /*S 58 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 60 Level: developer 61 62 Notes: 63 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, 64 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 65 by `PetscLayoutGetLocalSize()` and the range of indices for a given MPI process is provided by `PetscLayoutGetRange()`. 66 67 Before calling `PetscLayoutSetUp()`, one must call either (or both) `PetscLayoutSetSize()` or `PetscLayoutSetLocalSize()`, 68 69 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, 70 for example with `VecGetLocalSize()` and `VecGetOwnershipRange()`. 71 72 Similarly PETSc matrices have layouts, these are discussed in [](ch_matrices). 73 74 .seealso: `PetscLayoutCreate()`, `PetscLayoutDestroy()`, `PetscLayoutGetRange()`, `PetscLayoutGetLocalSize()`, `PetscLayoutGetSize()`, 75 `PetscLayoutGetBlockSize()`, `PetscLayoutGetRanges()`, `PetscLayoutFindOwner()`, `PetscLayoutFindOwnerIndex()`, 76 `VecGetLayout()`, `VecGetLocalSize()`, `VecGetOwnershipRange()`, `PetscLayoutSetUp()`, `PetscLayoutSetSize()`, `PetscLayoutSetLocalSize()` 77 S*/ 78 typedef struct _n_PetscLayout *PetscLayout; 79