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 11 program ex40f90 12 13#include <petsc/finclude/petscsnes.h> 14#include <petsc/finclude/petscdmda.h> 15 use petscsnes 16 use petscdmda 17 implicit none 18 19 SNES snes 20 PetscErrorCode ierr 21 DM da 22 PetscInt ten,two,one 23 PetscScalar sone 24 Vec x 25 external FormFunctionLocal 26 27 PetscCallA(PetscInitialize(ierr)) 28 ten = 10 29 one = 1 30 two = 2 31 sone = 1.0 32 33 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,PETSC_NULL_INTEGER,da,ierr)) 34 PetscCallA(DMSetFromOptions(da,ierr)) 35 PetscCallA(DMSetUp(da,ierr)) 36 37! Create solver object and associate it with the unknowns (on the grid) 38 39 PetscCallA(SNESCreate(PETSC_COMM_WORLD,snes,ierr)) 40 PetscCallA(SNESSetDM(snes,da,ierr)) 41 42 PetscCallA(DMDASNESSetFunctionLocal(da,INSERT_VALUES,FormFunctionLocal,0,ierr)) 43 PetscCallA(SNESSetFromOptions(snes,ierr)) 44 45! Solve the nonlinear system 46! 47 PetscCallA(DMCreateGlobalVector(da,x,ierr)) 48 PetscCallA(VecSet(x,sone,ierr)) 49 PetscCallA(SNESSolve(snes,PETSC_NULL_VEC,x,ierr)) 50 51 PetscCallA(VecDestroy(x,ierr)) 52 PetscCallA(SNESDestroy(snes,ierr)) 53 PetscCallA(DMDestroy(da,ierr)) 54 PetscCallA(PetscFinalize(ierr)) 55 end 56 57 subroutine FormFunctionLocal(in,x,f,dummy,ierr) 58 implicit none 59 PetscInt i,j,k,dummy 60 DMDALocalInfo in(DMDA_LOCAL_INFO_SIZE) 61 PetscScalar x(in(DMDA_LOCAL_INFO_DOF),XG_RANGE,YG_RANGE) 62 PetscScalar f(in(DMDA_LOCAL_INFO_DOF),X_RANGE,Y_RANGE) 63 PetscErrorCode ierr 64 65 do i=in(DMDA_LOCAL_INFO_XS)+1,in(DMDA_LOCAL_INFO_XS)+in(DMDA_LOCAL_INFO_XM) 66 do j=in(DMDA_LOCAL_INFO_YS)+1,in(DMDA_LOCAL_INFO_YS)+in(DMDA_LOCAL_INFO_YM) 67 do k=1,in(DMDA_LOCAL_INFO_DOF) 68 f(k,i,j) = x(k,i,j)*x(k,i,j) - 2.0 69 enddo 70 enddo 71 enddo 72 73 return 74 end 75 76!/*TEST 77! 78! test: 79! args: -snes_monitor_short -snes_view -da_refine 1 -pc_type mg -pc_mg_type full -ksp_type fgmres -pc_mg_galerkin pmat 80! requires: !single 81! 82!TEST*/ 83