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 external FormFunctionLocal 24 25 PetscCallA(PetscInitialize(ierr)) 26 ten = 10 27 one = 1 28 two = 2 29 30 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)) 31 PetscCallA(DMSetFromOptions(da,ierr)) 32 PetscCallA(DMSetUp(da,ierr)) 33 34! Create solver object and associate it with the unknowns (on the grid) 35 36 PetscCallA(SNESCreate(PETSC_COMM_WORLD,snes,ierr)) 37 PetscCallA(SNESSetDM(snes,da,ierr)) 38 39 PetscCallA(DMDASNESSetFunctionLocal(da,INSERT_VALUES,FormFunctionLocal,0,ierr)) 40 PetscCallA(SNESSetFromOptions(snes,ierr)) 41 42! Solve the nonlinear system 43! 44 PetscCallA(SNESSolve(snes,PETSC_NULL_VEC,PETSC_NULL_VEC,ierr)) 45 46 PetscCallA(SNESDestroy(snes,ierr)) 47 PetscCallA(DMDestroy(da,ierr)) 48 PetscCallA(PetscFinalize(ierr)) 49 end 50 51 subroutine FormFunctionLocal(in,x,f,dummy,ierr) 52 implicit none 53 PetscInt i,j,k,dummy 54 DMDALocalInfo in(DMDA_LOCAL_INFO_SIZE) 55 PetscScalar x(in(DMDA_LOCAL_INFO_DOF),XG_RANGE,YG_RANGE) 56 PetscScalar f(in(DMDA_LOCAL_INFO_DOF),X_RANGE,Y_RANGE) 57 PetscErrorCode ierr 58 59 do i=in(DMDA_LOCAL_INFO_XS)+1,in(DMDA_LOCAL_INFO_XS)+in(DMDA_LOCAL_INFO_XM) 60 do j=in(DMDA_LOCAL_INFO_YS)+1,in(DMDA_LOCAL_INFO_YS)+in(DMDA_LOCAL_INFO_YM) 61 do k=1,in(DMDA_LOCAL_INFO_DOF) 62 f(k,i,j) = x(k,i,j)*x(k,i,j) - 2.0 63 enddo 64 enddo 65 enddo 66 67 return 68 end 69 70!/*TEST 71! 72! test: 73! args: -snes_monitor_short -snes_view -da_refine 1 -pc_type mg -pc_mg_type full -ksp_type fgmres -pc_mg_galerkin pmat 74! requires: !single 75! 76!TEST*/ 77