8   Collective (if `N` is `PETSC_DECIDE`)
13 . n    - local length (or `PETSC_DECIDE` to have it set)
14 - N    - global length (or `PETSC_DECIDE`)
19   `n` and `N` cannot be both `PETSC_DECIDE`
21   If one processor calls this with `N` of `PETSC_DECIDE` then all processors
26 PetscErrorCode PetscSplitOwnershipBlock(MPI_Comm comm, PetscInt bs, PetscInt *n, PetscInt *N)  in PetscSplitOwnershipBlock()  argument
31 …PetscCheck(*N != PETSC_DECIDE || *n != PETSC_DECIDE, PETSC_COMM_SELF, PETSC_ERR_ARG_INCOMP, "Both …  in PetscSplitOwnershipBlock()
33   if (*N == PETSC_DECIDE) {  in PetscSplitOwnershipBlock()
34 …PetscCheck(*n % bs == 0, PETSC_COMM_SELF, PETSC_ERR_ARG_INCOMP, "local size %" PetscInt_FMT " not …  in PetscSplitOwnershipBlock()
35     PetscCallMPI(MPIU_Allreduce(n, N, 1, MPIU_INT, MPI_SUM, comm));  in PetscSplitOwnershipBlock()
36   } else if (*n == PETSC_DECIDE) {  in PetscSplitOwnershipBlock()
37     PetscInt Nbs = *N / bs;  in PetscSplitOwnershipBlock()
40     *n = bs * (Nbs / size + ((Nbs % size) > rank));  in PetscSplitOwnershipBlock()
49   Collective (if `n` or `N` is `PETSC_DECIDE` or `PETSC_DETERMINE`)
53 . n    - local length (or `PETSC_DECIDE` to have it set)
54 - N    - global length (or `PETSC_DETERMINE` to have it set)
59   `n` and `N` cannot be both `PETSC_DECIDE` and `PETSC_DETERMINE`
61 …If one processor calls this with `n` of `PETSC_DECIDE` (or with `N` `PETSC_DETERMINE`) then all pr…
67 PetscErrorCode PetscSplitOwnership(MPI_Comm comm, PetscInt *n, PetscInt *N)  in PetscSplitOwnership()  argument
72 …PetscCheck(*N != PETSC_DECIDE || *n != PETSC_DECIDE, PETSC_COMM_SELF, PETSC_ERR_ARG_INCOMP, "Both …  in PetscSplitOwnership()
75     l[0] = (*n == PETSC_DECIDE) ? 1 : 0;  in PetscSplitOwnership()
76     l[1] = (*N == PETSC_DECIDE) ? 1 : 0;  in PetscSplitOwnership()
83   if (*N == PETSC_DECIDE) {  in PetscSplitOwnership()
84     PetscCallMPI(MPIU_Allreduce(n, N, 1, MPIU_INT, MPI_SUM, comm));  in PetscSplitOwnership()
85   } else if (*n == PETSC_DECIDE) {  in PetscSplitOwnership()
88     *n = *N / size + ((*N % size) > rank);  in PetscSplitOwnership()
91     PetscCallMPI(MPIU_Allreduce(n, &tmp, 1, MPIU_INT, MPI_SUM, comm));  in PetscSplitOwnership()
92 …N, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Sum of local lengths %" PetscInt_FMT " does not equal glob…  in PetscSplitOwnership()
101   Collective (if `n` or `N` is `PETSC_DECIDE`)
105 . n    - local length (or `PETSC_DECIDE` to have it set)
106 - N    - global length (or `PETSC_DECIDE`)
113   the local sizes when splitting `N`=50 with 6 processes are 9,9,9,9,9,5
115   n and N cannot be both `PETSC_DECIDE`
117   If one processor calls this with `n` or `N` of `PETSC_DECIDE` then all processors
123 PetscErrorCode PetscSplitOwnershipEqual(MPI_Comm comm, PetscInt *n, PetscInt *N)  in PetscSplitOwnershipEqual()  argument
128 …PetscCheck(*N != PETSC_DECIDE || *n != PETSC_DECIDE, PETSC_COMM_SELF, PETSC_ERR_ARG_INCOMP, "Both …  in PetscSplitOwnershipEqual()
131     l[0] = (*n == PETSC_DECIDE) ? 1 : 0;  in PetscSplitOwnershipEqual()
132     l[1] = (*N == PETSC_DECIDE) ? 1 : 0;  in PetscSplitOwnershipEqual()
139   if (*N == PETSC_DECIDE) {  in PetscSplitOwnershipEqual()
140     PetscCallMPI(MPIU_Allreduce(n, N, 1, MPIU_INT, MPI_SUM, comm));  in PetscSplitOwnershipEqual()
141   } else if (*n == PETSC_DECIDE) {  in PetscSplitOwnershipEqual()
144     *n = *N / size;  in PetscSplitOwnershipEqual()
145     if (*N % size) {  in PetscSplitOwnershipEqual()
146       if ((rank + 1) * (*n + 1) <= *N) *n = *n + 1;  in PetscSplitOwnershipEqual()
147       else if (rank * (*n + 1) <= *N) *n = *N - rank * (*n + 1);  in PetscSplitOwnershipEqual()
148       else *n = 0;  in PetscSplitOwnershipEqual()
152     PetscCallMPI(MPIU_Allreduce(n, &tmp, 1, MPIU_INT, MPI_SUM, comm));  in PetscSplitOwnershipEqual()
153 …N, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Sum of local lengths %" PetscInt_FMT " does not equal glob…  in PetscSplitOwnershipEqual()