Actual source code: ex88f.F90
1: !
2: ! Creates a tridiagonal sparse matrix explicitly in Fortran and solves a linear system with it
3: !
4: ! The matrix is provided in triples in a way that supports new nonzero values with the same nonzero structure
5: !
6: program main
7: #include <petsc/finclude/petscksp.h>
8: use petscksp
9: implicit none
11: PetscInt i, n
12: PetscCount nz
13: PetscBool flg
14: PetscErrorCode ierr
15: PetscScalar, ALLOCATABLE :: a(:)
16: PetscScalar, pointer :: b(:)
18: PetscInt, ALLOCATABLE :: rows(:)
19: PetscInt, ALLOCATABLE :: cols(:)
21: Mat J
22: Vec rhs, solution
23: KSP ksp
25: PetscCallA(PetscInitialize(ierr))
27: n = 3
28: PetscCallA(PetscOptionsGetInt(PETSC_NULL_OPTIONS, PETSC_NULL_CHARACTER, '-n', n, flg, ierr))
29: nz = 3*n - 4
31: PetscCallA(VecCreateSeq(PETSC_COMM_SELF, n, rhs, ierr))
32: PetscCallA(VecCreateSeq(PETSC_COMM_SELF, n, solution, ierr))
33: ALLOCATE (rows(nz), cols(nz), a(nz))
35: PetscCallA(VecGetArray(rhs, b, ierr))
36: do i = 1, n
37: b(i) = 1.0
38: end do
39: PetscCallA(VecRestoreArray(rhs, b, ierr))
41: rows(1) = 0; cols(1) = 0
42: a(1) = 1.0
43: do i = 2, n - 1
44: rows(2 + 3*(i - 2)) = i - 1; cols(2 + 3*(i - 2)) = i - 2
45: a(2 + 3*(i - 2)) = -1.0
46: rows(2 + 3*(i - 2) + 1) = i - 1; cols(2 + 3*(i - 2) + 1) = i - 1
47: a(2 + 3*(i - 2) + 1) = 2.0
48: rows(2 + 3*(i - 2) + 2) = i - 1; cols(2 + 3*(i - 2) + 2) = i
49: a(2 + 3*(i - 2) + 2) = -1.0
50: end do
51: rows(nz) = n - 1; cols(nz) = n - 1
52: a(nz) = 1.0
54: PetscCallA(MatCreate(PETSC_COMM_SELF, J, ierr))
55: PetscCallA(MatSetSizes(J, n, n, n, n, ierr))
56: PetscCallA(MatSetType(J, MATSEQAIJ, ierr))
57: PetscCallA(MatSetPreallocationCOO(J, nz, rows, cols, ierr))
58: PetscCallA(MatSetValuesCOO(J, a, INSERT_VALUES, ierr))
60: PetscCallA(KSPCreate(PETSC_COMM_SELF, ksp, ierr))
61: PetscCallA(KSPSetErrorIfNotConverged(ksp, PETSC_TRUE, ierr))
62: PetscCallA(KSPSetFromOptions(ksp, ierr))
63: PetscCallA(KSPSetOperators(ksp, J, J, ierr))
65: PetscCallA(KSPSolve(ksp, rhs, solution, ierr))
67: ! Keep the same size and nonzero structure of the matrix but change its numerical entries
68: do i = 2, n - 1
69: a(2 + 3*(i - 2) + 1) = 4.0
70: end do
71: PetscCallA(MatSetValuesCOO(J, a, INSERT_VALUES, ierr))
73: PetscCallA(KSPSolve(ksp, rhs, solution, ierr))
75: PetscCallA(KSPDestroy(ksp, ierr))
76: PetscCallA(VecDestroy(rhs, ierr))
77: PetscCallA(VecDestroy(solution, ierr))
78: PetscCallA(MatDestroy(J, ierr))
80: DEALLOCATE (rows, cols, a)
82: PetscCallA(PetscFinalize(ierr))
83: end
85: !/*TEST
86: !
87: ! test:
88: ! requires: defined(PETSC_USE_SINGLE_LIBRARY)
89: ! nsize: 3
90: ! filter: sed 's?ATOL?RTOL?g' | grep -v HERMITIAN | grep -v "shared memory" | grep -v "Mat_0"
91: ! # use the MPI Linear Solver Server
92: ! args: -n 20 -mpi_linear_solver_server -mpi_linear_solver_server_view -mpi_linear_solver_server_use_shared_memory false
93: ! # controls for the use of PCMPI on a particular system
94: ! args: -mpi_linear_solver_server_minimum_count_per_rank 5 -mpi_linear_solver_server_ksp_view
95: ! # the usual options for the linear solver (in this case using the server)
96: ! args: -ksp_monitor -ksp_converged_reason -ksp_view
97: !
98: ! test:
99: ! suffix: 2
100: ! requires: defined(PETSC_USE_SINGLE_LIBRARY)
101: ! nsize: 3
102: ! filter: sed 's?ATOL?RTOL?g' | grep -v HERMITIAN | grep -v "shared memory" | grep -v "Mat_0"
103: ! # use the MPI Linear Solver Server
104: ! args: -n 20 -mpi_linear_solver_server -mpi_linear_solver_server_view -mpi_linear_solver_server_use_shared_memory false
105: ! # controls for the use of PCMPI on a particular system
106: ! args: -mpi_linear_solver_server_ksp_view
107: ! # the usual options for the linear solver (in this case using the server)
108: ! args: -ksp_monitor -ksp_converged_reason -ksp_view
109: !
110: !TEST*/