Actual source code: ex40f90.F90
1: !
2: ! Demonstrates use of DMDASNESSetFunctionLocal() from Fortran
3: !
4: ! Note: the access to the entries of the local arrays below use the Fortran
5: ! convention of starting at zero. However calls to MatSetValues() start at 0.
6: ! Also note that you will have to map the i,j,k coordinates to the local PETSc ordering
7: ! before calling MatSetValuesLocal(). Often you will find that using PETSc's default
8: ! code for computing the Jacobian works fine and you will not need to implement
9: ! your own FormJacobianLocal().
10: #include <petsc/finclude/petscsnes.h>
11: #include <petsc/finclude/petscdmda.h>
12: module ex40f90module
13: use petscdmda
14: implicit none
15: contains
16: subroutine FormFunctionLocal(in, x, f, dummy, ierr)
17: PetscInt i, j, k, dummy
18: DMDALocalInfo in
19: PetscScalar x(in%DOF, in%GXS + 1:in%GXS + in%GXM, in%GYS + 1:in%GYS + in%GYM)
20: PetscScalar f(in%DOF, in%XS + 1:in%XS + in%XM, in%YS + 1:in%YS + in%YM)
21: PetscErrorCode ierr
23: do i = in%XS + 1, in%XS + in%XM
24: do j = in%YS + 1, in%YS + in%YM
25: do k = 1, in%DOF
26: f(k, i, j) = x(k, i, j)*x(k, i, j) - 2.0
27: end do
28: end do
29: end do
31: end
32: end module ex40f90module
34: program ex40f90
35: use petscdmda
36: use petscsnes
37: use ex40f90module
38: implicit none
40: SNES snes
41: PetscErrorCode ierr
42: DM da
43: PetscInt ten, two, one
44: PetscScalar sone
45: Vec x
47: PetscCallA(PetscInitialize(ierr))
48: ten = 10
49: one = 1
50: two = 2
51: sone = 1.0
53: PetscCallA(DMDACreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DMDA_STENCIL_BOX, ten, ten, PETSC_DECIDE, PETSC_DECIDE, two, one, PETSC_NULL_INTEGER_ARRAY, PETSC_NULL_INTEGER_ARRAY, da, ierr))
54: PetscCallA(DMSetFromOptions(da, ierr))
55: PetscCallA(DMSetUp(da, ierr))
57: ! Create solver object and associate it with the unknowns (on the grid)
59: PetscCallA(SNESCreate(PETSC_COMM_WORLD, snes, ierr))
60: PetscCallA(SNESSetDM(snes, da, ierr))
62: PetscCallA(DMDASNESSetFunctionLocal(da, INSERT_VALUES, FormFunctionLocal, 0, ierr))
63: PetscCallA(SNESSetFromOptions(snes, ierr))
65: ! Solve the nonlinear system
66: !
67: PetscCallA(DMCreateGlobalVector(da, x, ierr))
68: PetscCallA(VecSet(x, sone, ierr))
69: PetscCallA(SNESSolve(snes, PETSC_NULL_VEC, x, ierr))
71: PetscCallA(VecDestroy(x, ierr))
72: PetscCallA(SNESDestroy(snes, ierr))
73: PetscCallA(DMDestroy(da, ierr))
74: PetscCallA(PetscFinalize(ierr))
75: end
77: !/*TEST
78: !
79: ! test:
80: ! args: -snes_monitor_short -snes_view -da_refine 1 -pc_type mg -pc_mg_type full -ksp_type fgmres -pc_mg_galerkin pmat
81: ! requires: !single
82: !
83: !TEST*/